\input texinfo
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment %**start of header (This is for running Texinfo on a region)
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment No overfull hbox marks in the dvi file.
@finalout
@setfilename ../info/ccmode
@settitle CC Mode Manual
@footnotestyle end
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment @setchapternewpage odd !! we don't want blank pages !!
@comment %**end of header (This is for running Texinfo on a region)
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment
@comment Texinfo manual for CC Mode
@comment Generated from the original README file by Krishna Padmasola
@comment <krishna@earth-gw.njit.edu>
@comment
@comment Authors:
@comment Barry A. Warsaw
@comment Martin Stjernholm
@comment
@comment Maintained by Martin Stjernholm <bug-cc-mode@gnu.org>
@comment
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@macro copyrightblurb
Copyright @copyright{} 1995, 96, 97, 98, 99, 2000, 01 Free Software Foundation, Inc.
@end macro
@comment Info directory entry for use by install-info. The indentation
@comment here is by request from the FSF folks.
@dircategory Emacs
@direntry
* CC Mode: (ccmode). Emacs mode for editing C, C++, Objective-C,
Java, Pike, and IDL code.
@end direntry
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment The following lines inserts the copyright notice
@comment into the Info file.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@ifnottex
Copyright @copyright{} 1995, 96, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with the
Invariant Sections being ``The GNU Manifesto'', ``Distribution'' and
``GNU GENERAL PUBLIC LICENSE'', with the Front-Cover texts being ``A GNU
Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
license is included in the section entitled ``GNU Free Documentation
License'' in the Emacs manual.
(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
this GNU Manual, like GNU software. Copies published by the Free
Software Foundation raise funds for GNU development.''
This document is part of a collection distributed under the GNU Free
Documentation License. If you want to distribute this document
separately from the collection, you can do so by adding a copy of the
license to the document, as described in section 6 of the license.
@end ifnottex
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment TeX title page
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@titlepage
@sp 10
@center @titlefont{CC Mode 5.28}
@sp 2
@center @subtitlefont{A GNU Emacs mode for editing C and C-like languages}
@sp 2
@center Barry A. Warsaw, Martin Stjernholm
@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1995, 96, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc.
@sp 1
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with the
Invariant Sections being ``The GNU Manifesto'', ``Distribution'' and
``GNU GENERAL PUBLIC LICENSE'', with the Front-Cover texts being ``A GNU
Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
license is included in the section entitled ``GNU Free Documentation
License'' in the Emacs manual.
(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
this GNU Manual, like GNU software. Copies published by the Free
Software Foundation raise funds for GNU development.''
This document is part of a collection distributed under the GNU Free
Documentation License. If you want to distribute this document
separately from the collection, you can do so by adding a copy of the
license to the document, as described in section 6 of the license.
@end titlepage
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment The Top node contains the master menu for the Info file.
@comment This appears only in the Info file, not the printed manual.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Top, Introduction, (dir), (dir)
@comment node-name, next, previous, up
@macro ccmode
CC Mode
@end macro
@ifinfo
@top @ccmode{}
@ccmode{} is a GNU Emacs mode for editing files containing C, C++,
Objective-C, Java, CORBA IDL, and Pike code. It provides syntax-based
indentation and has several handy commands and some minor modes to make
the editing easier. Note that @ccmode{} does @emph{not} provide
font-locking; there are other Emacs packages for that.
@end ifinfo
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@menu
* Introduction::
* Getting Connected::
* New Indentation Engine::
* Minor Modes::
* Text Filling and Line Breaking::
* Commands::
* Customizing Indentation::
* Syntactic Symbols::
* Indentation Functions::
* Performance Issues::
* Limitations and Known Bugs::
* Frequently Asked Questions::
* Getting the Latest CC Mode Release::
* Mailing Lists and Submitting Bug Reports::
* Sample .emacs File::
--- Indices ---
* Concept Index::
* Command Index::
* Key Index::
* Variable Index::
--- The Detailed Node Listing ---
New Indentation Engine
* Syntactic Analysis::
* Indentation Calculation::
Minor Modes
* Auto-newline Insertion::
* Hungry-deletion of Whitespace::
Auto-newline Insertion
* Hanging Braces::
* Hanging Colons::
* Hanging Semi-colons and Commas::
* Other Electric Commands::
* Clean-ups::
Commands
* Indentation Commands::
* Movement Commands::
* Other Commands::
Customizing Indentation
* Interactive Customization::
* Permanent Customization::
* Hooks::
* Styles::
* Advanced Customizations::
Styles
* Built-in Styles::
* Adding Styles::
* File Styles::
Advanced Customizations
* Custom Indentation Functions::
* Custom Brace and Colon Hanging::
* Customizing Semi-colons and Commas::
* Other Special Indentations::
@end menu
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Introduction, Getting Connected, Top, Top
@comment node-name, next, previous, up
@chapter Introduction
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@cindex BOCM
Welcome to @ccmode{}, a GNU Emacs mode for editing files containing C,
C++, Objective-C, Java, CORBA IDL, and Pike code. This incarnation of
the mode is descendant from @file{c-mode.el} (also called "Boring Old C
Mode" or BOCM @t{:-)}, and @file{c++-mode.el} version 2, which Barry has
been maintaining since 1992. @ccmode{} represents a significant
milestone in the mode's life. It has been fully merged back with Emacs
19's @file{c-mode.el}. Also a new, more intuitive and flexible mechanism
for controlling indentation has been developed. Late in 1997, Martin
joined the @ccmode{} Maintainers Team, and implemented the Pike support.
As of 2000 Martin has taken over as the sole maintainer.
This manual describes @ccmode{}
@comment The following line must appear on its own, so that the automated
version 5.28.
@comment Release.py script can update the version number automatically
@ccmode{} supports the editing of K&R and ANSI C, @dfn{ARM}
@footnote{@cite{The Annotated C++ Reference Manual}, by Ellis and
Stroustrup.} C++, Objective-C, Java, CORBA's Interface Definition
Language, and Pike@footnote{A C-like scripting language with its roots
in the LPC language used in some MUD engines. See
@uref{http://pike.idonex.se/}.} files. In this way, you can easily set
up consistent coding styles for use in editing all of these languages.
@ccmode{} does @emph{not} handle font-locking (a.k.a. syntax coloring,
keyword highlighting) or anything of that nature, for any of these
modes. Font-locking is handled by other Emacs packages.
This manual will describe the following:
@itemize @bullet
@item
How to get started using @ccmode{}.
@item
How the new indentation engine works.
@item
How to customize the new indentation engine.
@end itemize
@findex c-mode
@findex c++-mode
@findex objc-mode
@findex java-mode
@findex idl-mode
@findex pike-mode
Note that the name of this package is ``@ccmode{},'' but there is no top
level @code{cc-mode} entry point. All of the variables, commands, and
functions in @ccmode{} are prefixed with @code{c-@var{<thing>}}, and
@code{c-mode}, @code{c++-mode}, @code{objc-mode}, @code{java-mode},
@code{idl-mode}, and @code{pike-mode} entry points are provided. This
package is intended to be a replacement for @file{c-mode.el} and
@file{c++-mode.el}.
@cindex @file{cc-compat.el} file
This distribution also contains a file
called @file{cc-compat.el} which should ease your transition from BOCM
to @ccmode{}. If you have a BOCM configuration you are really happy
with, and want to postpone learning how to configure @ccmode{}, take a
look at that file. It maps BOCM configuration variables to @ccmode{}'s
new indentation model. It is not actively supported so for the long
run, you should learn how to customize @ccmode{} to support your coding
style.
A special word of thanks goes to Krishna Padmasola for his work in
converting the original @file{README} file to Texinfo format. I'd also
like to thank all the @ccmode{} victims who help enormously during the
early beta stages of @ccmode{}'s development.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Getting Connected, New Indentation Engine, Introduction, Top
@comment node-name, next, previous, up
@chapter Getting Connected
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
If you got this version of @ccmode{} with Emacs or XEmacs, it should
work just fine right out of the box. Note however that you may not have
the latest @ccmode{} release and may want to upgrade your copy.
If you are upgrading an existing @ccmode{} installation, please see the
@file{README} file for installation details. @ccmode{} may not work
with older versions of Emacs or XEmacs. See the @ccmode{} release notes
Web pages for the latest information on Emacs version and package
compatibility (@pxref{Getting the Latest CC Mode Release}).
@cindex @file{cc-mode-18.el} file
@emph{Note that @ccmode{} no longer
works with Emacs 18!}, so if you haven't upgraded from Emacs 18 by now,
you are out of luck.
@findex c-version
@findex version (c-)
You can find out what version of @ccmode{} you are using by visiting a C
file and entering @kbd{M-x c-version RET}. You should see this message in
the echo area:
@example
Using CC Mode version 5.XX
@end example
@noindent
where @samp{XX} is the minor release number.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node New Indentation Engine, Minor Modes, Getting Connected, Top
@comment node-name, next, previous, up
@chapter New Indentation Engine
@cindex indentation engine
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@ccmode{} has a new indentation engine, providing a simplified, yet
flexible and general mechanism for customizing indentation. It separates
indentation calculation into two steps: first, @ccmode{} analyzes the
line of code being indented to determine the kind of language construct
it's looking at, then it applies user defined offsets to the current
line based on this analysis.
This section will briefly cover how indentation is calculated in
@ccmode{}. It is important to understand the indentation model
being used so that you will know how to customize @ccmode{} for
your personal coding style.
@menu
* Syntactic Analysis::
* Indentation Calculation::
@end menu
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Syntactic Analysis, Indentation Calculation, , New Indentation Engine
@comment node-name, next, previous, up
@section Syntactic Analysis
@cindex syntactic analysis
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@cindex relative buffer position
@cindex syntactic symbol
@cindex syntactic component
@cindex syntactic component list
The first thing @ccmode{} does when indenting a line of code, is to
analyze the line, determining the @dfn{syntactic component list} of the
construct on that line. A syntactic component consists of a pair of
information (in lisp parlance, a @emph{cons cell}), where the first part
is a @dfn{syntactic symbol}, and the second part is a @dfn{relative
buffer position}. Syntactic symbols describe elements of C code
@footnote{Unless otherwise noted, the term ``C code'' to refers to all
the C-like languages.}, e.g. @code{statement}, @code{substatement},
@code{class-open}, @code{class-close}, etc. @xref{Syntactic Symbols},
for a complete list of currently recognized syntactic symbols and their
semantics. The style variable @code{c-offsets-alist} also contains the
list of currently supported syntactic symbols.
Conceptually, a line of C code is always indented relative to the
indentation of some line higher up in the buffer. This is represented
by the relative buffer position in the syntactic component.
Here is an example. Suppose we had the following code as the only thing
in a C++ buffer @footnote{The line numbers in this and future examples
don't actually appear in the buffer, of course!}:
@example
@group
1: void swap( int& a, int& b )
2: @{
3: int tmp = a;
4: a = b;
5: b = tmp;
6: @}
@end group
@end example
@kindex C-c C-s
@findex c-show-syntactic-information
@findex show-syntactic-information (c-)
We can use the command @kbd{C-c C-s}
(@code{c-show-syntactic-information}) to simply report what the
syntactic analysis is for the current line. Running this command on
line 4 of this example, we'd see in the echo area@footnote{With a universal
argument (i.e. @kbd{C-u C-c C-s}) the analysis is inserted into the
buffer as a comment
on the current line.}:
@example
((statement . 35))
@end example
This tells us that the line is a statement and it is indented relative
to buffer position 35, which happens to be the @samp{i} in @code{int} on
line 3. If you were to move point to line 3 and hit @kbd{C-c C-s}, you
would see:
@example
((defun-block-intro . 29))
@end example
This indicates that the @samp{int} line is the first statement in a top
level function block, and is indented relative to buffer position 29,
which is the brace just after the function header.
Here's another example:
@example
@group
1: int add( int val, int incr, int doit )
2: @{
3: if( doit )
4: @{
5: return( val + incr );
6: @}
7: return( val );
8: @}
@end group
@end example
@noindent
Hitting @kbd{C-c C-s} on line 4 gives us:
@example
((substatement-open . 46))
@end example
@cindex substatement
@cindex substatement block
@noindent
which tells us that this is a brace that @emph{opens} a substatement
block. @footnote{A @dfn{substatement} is the line after a
conditional statement, such as @code{if}, @code{else}, @code{while},
@code{do}, @code{switch}, etc. A @dfn{substatement
block} is a brace block following one of these conditional statements.}
@cindex comment-only line
Syntactic component lists can contain more than one component, and
individual syntactic components need not have relative buffer positions.
The most common example of this is a line that contains a @dfn{comment
only line}.
@example
@group
1: void draw_list( List<Drawables>& drawables )
2: @{
3: // call the virtual draw() method on each element in list
4: for( int i=0; i < drawables.count(), ++i )
5: @{
6: drawables[i].draw();
7: @}
8: @}
@end group
@end example
@noindent
Hitting @kbd{C-c C-s} on line 3 of this example gives:
@example
((comment-intro) (defun-block-intro . 46))
@end example
@noindent
and you can see that the syntactic component list contains two syntactic
components. Also notice that the first component,
@samp{(comment-intro)} has no relative buffer position.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Indentation Calculation, , Syntactic Analysis, New Indentation Engine
@comment node-name, next, previous, up
@section Indentation Calculation
@cindex indentation calculation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Indentation for a line is calculated using the syntactic
component list derived in step 1 above (@pxref{Syntactic Analysis}).
Each component contributes to the final total indentation of the line in
two ways.
First, the syntactic symbols are looked up in the @code{c-offsets-alist}
style variable, which is an association list of syntactic symbols and
the offsets to apply for those symbols. These offsets are added to a
running total.
Second, if the component has a relative buffer position, @ccmode{}
adds the column number of that position to the running total. By adding
up the offsets and columns for every syntactic component on the list,
the final total indentation for the current line is computed.
Let's use our two code examples above to see how this works. Here is
our first example again:
@example
@group
1: void swap( int& a, int& b )
2: @{
3: int tmp = a;
4: a = b;
5: b = tmp;
6: @}
@end group
@end example
Let's say point is on line 3 and we hit the @kbd{TAB} key to re-indent
the line. Remember that the syntactic component list for that
line is:
@example
((defun-block-intro . 29))
@end example
@noindent
@ccmode{} looks up @code{defun-block-intro} in the
@code{c-offsets-alist} style variable. Let's say it finds the value
@samp{4}; it adds this to the running total (initialized to zero),
yielding a running total indentation of 4 spaces.
Next @ccmode{} goes to buffer position 29 and asks for the current
column. This brace is in column zero, so @ccmode{}
adds @samp{0} to the running total. Since there is only one syntactic
component on the list for this line, indentation calculation is
complete, and the total indentation for the line
is 4 spaces.
Here's another example:
@example
@group
1: int add( int val, int incr, int doit )
2: @{
3: if( doit )
4: @{
5: return( val + incr );
6: @}
7: return( val );
8: @}
@end group
@end example
If we were to hit @kbd{TAB} on line 4 in the above example, the same
basic process is performed, despite the differences in the syntactic
component list. Remember that the list for this line is:
@example
((substatement-open . 46))
@end example
Here, @ccmode{} first looks up the @code{substatement-open} symbol
in @code{c-offsets-alist}. Let's say it finds the value @samp{4}. This
yields a running total of 4. @ccmode{} then goes to
buffer position 46, which is the @samp{i} in @code{if} on line 3. This
character is in the fourth column on that line so adding this to the
running total yields an indentation for the line of 8 spaces.
Simple, huh?
Actually, the mode usually just does The Right Thing without you having
to think about it in this much detail. But when customizing
indentation, it's helpful to understand the general indentation model
being used.
@vindex c-echo-syntactic-information-p
@vindex echo-syntactic-information-p (c-)
As you configure @ccmode{}, you might want to set the variable
@code{c-echo-syntactic-information-p} to non-@code{nil} so that the
syntactic component list and calculated offset will always be echoed in
the minibuffer when you hit @kbd{TAB}.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Minor Modes, Text Filling and Line Breaking, New Indentation Engine, Top
@comment node-name, next, previous, up
@chapter Minor Modes
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@ccmode{} contains two minor-mode-like features that you should
find useful while you enter new C code. The first is called
@dfn{auto-newline} mode, and the second is called @dfn{hungry-delete}
mode. These minor modes can be toggled on and off independently, and
@ccmode{} can be configured so that it starts up with any
combination of these minor modes. By default, both of these minor modes
are turned off.
The state of the minor modes is always reflected in the minor mode list
on the modeline of the @ccmode{} buffer. When auto-newline mode is
enabled, you will see @samp{C/a} on the mode line @footnote{The @samp{C}
would be replaced with @samp{C++}, @samp{ObjC}, @samp{Java}, @samp{IDL},
or @samp{Pike} for the respective languages.}. When hungry delete mode
is enabled you would see @samp{C/h} and when both modes are enabled,
you'd see @samp{C/ah}.
@kindex C-c C-a
@kindex C-c C-d
@kindex C-c C-t
@findex c-toggle-hungry-state
@findex c-toggle-auto-state
@findex c-toggle-auto-hungry-state
@findex toggle-hungry-state (c-)
@findex toggle-auto-state (c-)
@findex toggle-auto-hungry-state (c-)
@ccmode{} provides key bindings which allow you to toggle the minor
modes on the fly while editing code. To toggle just the auto-newline
state, hit @kbd{C-c C-a} (@code{c-toggle-auto-state}). When you do
this, you should see the @samp{a} indicator either appear or disappear
on the modeline. Similarly, to toggle just the hungry-delete state, use
@kbd{C-c C-d} (@code{c-toggle-hungry-state}), and to toggle both states,
use @kbd{C-c C-t} (@code{c-toggle-auto-hungry-state}).
To set up the auto-newline and hungry-delete states to your preferred
values, you would need to add some lisp to your @file{.emacs} file that
called one of the @code{c-toggle-*-state} functions directly. When
called programmatically, each function takes a numeric value, where
a positive number enables the minor mode, a negative number disables the
mode, and zero toggles the current state of the mode.
So for example, if you wanted to enable both auto-newline and
hungry-delete for all your C file editing, you could add the following
to your @file{.emacs} file:
@example
(add-hook 'c-mode-common-hook
(lambda () (c-toggle-auto-hungry-state 1)))
@end example
@cindex electric characters
@menu
* Auto-newline Insertion::
* Hungry-deletion of Whitespace::
@end menu
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Auto-newline Insertion, Hungry-deletion of Whitespace, , Minor Modes
@comment node-name, next, previous, up
@section Auto-newline Insertion
@cindex auto-newline insertion
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@cindex electric commands
Auto-newline minor mode works by enabling certain @dfn{electric
commands}. Electric commands are typically bound to special characters
such as the left and right braces, colons, semi-colons, etc., which when
typed, perform some magic formatting in addition to inserting the typed
character. As a general rule, electric commands are only electric when
the following conditions apply:
@itemize @bullet
@item
Auto-newline minor mode is enabled, as evidenced by a @samp{C/a} or
@samp{C/ah} indicator on the modeline.
@cindex literal
@cindex syntactic whitespace
@item
The character was not typed inside of a literal @footnote{A
@dfn{literal} is defined as any comment, string, or C preprocessor macro
definition. These constructs are also known as @dfn{syntactic
whitespace} since they are usually ignored when scanning C code.}.
@item
@kindex C-u
No numeric argument was supplied to the command (i.e. it was typed as
normal, with no @kbd{C-u} prefix).
@end itemize
@menu
* Hanging Braces::
* Hanging Colons::
* Hanging Semi-colons and Commas::
* Other Electric Commands::
* Clean-ups::
@end menu
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Hanging Braces, Hanging Colons, , Auto-newline Insertion
@comment node-name, next, previous, up
@subsection Hanging Braces
@cindex hanging braces
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@findex c-electric-brace
@findex electric-brace (c-)
@vindex c-hanging-braces-alist
@vindex hanging-braces-alist (c-)
When you type either an open or close brace (i.e. @kbd{@{} or @kbd{@}}),
the electric command @code{c-electric-brace} gets run. This command has
two electric formatting behaviors. First, it will perform some
re-indentation of the line the brace was typed on, and second, it will
add various newlines before and/or after the typed brace.
Re-indentation occurs automatically whenever the electric behavior is
enabled. If the brace ends up on a line other than the one it was typed
on, then that line is also re-indented.
@cindex class-open syntactic symbol
@cindex class-close syntactic symbol
@cindex defun-open syntactic symbol
@cindex defun-close syntactic symbol
@cindex inline-open syntactic symbol
@cindex inline-close syntactic symbol
@cindex brace-list-open syntactic symbol
@cindex brace-list-close syntactic symbol
@cindex brace-list-intro syntactic symbol
@cindex brace-entry-open syntactic symbol
@cindex block-open syntactic symbol
@cindex block-close syntactic symbol
@cindex substatement-open syntactic symbol
@cindex statement-case-open syntactic symbol
@cindex extern-lang-open syntactic symbol
@cindex extern-lang-close syntactic symbol
@cindex namespace-open syntactic symbol
@cindex namespace-close syntactic symbol
@cindex inexpr-class-open symbol
@cindex inexpr-class-close symbol
The default in auto-newline mode is to insert newlines both before and
after a brace, but that can be controlled by the
@code{c-hanging-braces-alist} style variable. This variable contains a
mapping between syntactic symbols related to braces, and a list of
places to insert a newline. The syntactic symbols that are useful for
this list are: @code{class-open}, @code{class-close}, @code{defun-open},
@code{defun-close}, @code{inline-open}, @code{inline-close},
@code{brace-list-open}, @code{brace-list-close},
@code{brace-list-intro}, @code{brace-entry-open}, @code{block-open},
@code{block-close}, @code{substatement-open},
@code{statement-case-open}, @code{extern-lang-open},
@code{extern-lang-close}, @code{namespace-open}, @code{namespace-close},
@code{inexpr-class-open}, and @code{inexpr-class-close}@footnote{Note
that the aggregate constructs in Pike mode, @samp{(@{}, @samp{@})},
@samp{([}, @samp{])}, and @samp{(<}, @samp{>)}, do not count as brace
lists in this regard, even though they do for normal indentation
purposes. It's currently not possible to set automatic newlines on
these constructs.}. @xref{Syntactic Symbols}, for a more detailed
description of these syntactic symbols, except for
@code{inexpr-class-open} and @code{inexpr-class-close}, which aren't
actual syntactic symbols.
The braces of anonymous inner classes in Java are given the special
symbols @code{inexpr-class-open} and @code{inexpr-class-close}, so that
they can be distinguished from the braces of normal classes@footnote{The
braces of anonymous classes produces a combination of
@code{inexpr-class}, and @code{class-open} or @code{class-close} in
normal indentation analysis.}.
The value associated with each syntactic symbol in this association list
is called an @var{ACTION} which can be either a function or a list.
@xref{Custom Brace and Colon Hanging}, for a more detailed discussion of
using a function as a brace hanging @var{ACTION}.
When the @var{ACTION} is a list, it can contain any combination of the
symbols @code{before} and @code{after}, directing @ccmode{} where to
put newlines in relationship to the brace being inserted. Thus, if the
list contains only the symbol @code{after}, then the brace is said to
@dfn{hang} on the right side of the line, as in:
@example
@group
// here, open braces always `hang'
void spam( int i ) @{
if( i == 7 ) @{
dosomething(i);
@}
@}
@end group
@end example
When the list contains both @code{after} and @code{before}, the braces
will appear on a line by themselves, as shown by the close braces in the
above example. The list can also be empty, in which case no newlines
are added either before or after the brace.
If a syntactic symbol is missing entirely from
@code{c-hanging-braces-alist}, it's treated in the same way as an
@var{ACTION} with a list containing @code{before} and @code{after}, so
that braces by default end up on their own line.
For example, the default value of @code{c-hanging-braces-alist} is:
@example
@group
((brace-list-open)
(brace-entry-open)
(substatement-open after)
(block-close . c-snug-do-while)
(extern-lang-open after)
(inexpr-class-open after)
(inexpr-class-close before))
@end group
@end example
@noindent which says that @code{brace-list-open} and
@code{brace-entry-open} braces should both hang on the right side, and
allow subsequent text to follow on the same line as the brace. Also,
@code{substatement-open}, @code{extern-lang-open}, and
@code{inexpr-class-open} braces should hang on the right side, but
subsequent text should follow on the next line. The opposite holds for
@code{inexpr-class-close} braces; they won't hang, but the following
text continues on the same line. Here, in the @code{block-close} entry,
you also see an example of using a function as an @var{ACTION}. In all
other cases, braces are put on a line by themselves.
A word of caution: it is not a good idea to hang top-level construct
introducing braces, such as @code{class-open} or @code{defun-open}.
Emacs makes an assumption that such braces will always appear in column
zero, hanging them can introduce performance problems.
@xref{Performance Issues}, for more information.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Hanging Colons, Hanging Semi-colons and Commas, Hanging Braces, Auto-newline Insertion
@comment node-name, next, previous, up
@subsection Hanging Colons
@cindex hanging colons
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex hanging-colons-alist (c-)
@vindex c-hanging-colons-alist
Using a mechanism similar to brace hanging (@pxref{Hanging Braces}),
colons can also be made to hang using the style variable
@code{c-hanging-colons-alist}. The syntactic symbols appropriate for
this association list are: @code{case-label}, @code{label},
@code{access-label}, @code{member-init-intro}, and @code{inher-intro}.
Note however that for @code{c-hanging-colons-alist}, @var{ACTION}s as
functions are not supported. See also @ref{Custom Brace and Colon
Hanging} for details.
In C++, double-colons are used as a scope operator but because these
colons always appear right next to each other, newlines before and after
them are controlled by a different mechanism, called @dfn{clean-ups} in
@ccmode{}. @xref{Clean-ups}, for details.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Hanging Semi-colons and Commas, Other Electric Commands, Hanging Colons, Auto-newline Insertion
@comment node-name, next, previous, up
@subsection Hanging Semi-colons and Commas
@cindex hanging semi-colons
@cindex hanging commas
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Semicolons and commas are also electric in @ccmode{}, but since
these characters do not correspond directly to syntactic symbols, a
different mechanism is used to determine whether newlines should be
automatically inserted after these characters. @xref{Customizing
Semi-colons and Commas}, for details.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Other Electric Commands, Clean-ups, Hanging Semi-colons and Commas, Auto-newline Insertion
@comment node-name, next, previous, up
@subsection Other Electric Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@kindex #
@findex c-electric-pound
@vindex c-electric-pound-behavior
@findex electric-pound (c-)
@vindex electric-pound-behavior (c-)
A few other keys also provide electric behavior. For example
@kbd{#} (@code{c-electric-pound}) is electric when typed as
the first non-whitespace character on a line. In this case, the
variable @code{c-electric-pound-behavior} is consulted for the electric
behavior. This variable takes a list value, although the only element
currently defined is @code{alignleft}, which tells this command to force
the @samp{#} character into column zero. This is useful for entering
C preprocessor macro definitions.
@findex c-electric-star
@findex c-electric-slash
@findex electric-star (c-)
@findex electric-slash (c-)
Stars and slashes (i.e. @kbd{*} and @kbd{/}, @code{c-electric-star} and
@code{c-electric-slash} respectively) are also electric under
certain circumstances. If a star is inserted as the second character of
a C style block comment on a comment-only line, then the comment
delimiter is indented as defined by @code{c-offsets-alist}. A
comment-only line is defined as a line which contains only a comment, as
in:
@example
@group
void spam( int i )
@{
// this is a comment-only line...
if( i == 7 ) // but this is not
@{
dosomething(i);
@}
@}
@end group
@end example
Likewise, if a slash is inserted as the second slash in a C++ style line
comment (also only on a comment-only line), then the line is indented as
defined by @code{c-offsets-alist}.
@findex c-electric-lt-gt
@findex electric-lt-gt (c-)
@kindex <
@kindex >
Less-than and greater-than signs (@code{c-electric-lt-gt}) are also
electric, but only in C++ mode. Hitting the second of two @kbd{<} or
@kbd{>} keys re-indents the line if it is a C++ style stream operator.
@findex c-electric-paren
@findex electric-paren (c-)
@kindex (
@kindex )
The normal parenthesis characters @samp{(} and @samp{)} also reindent
the current line if they are used in normal code. This is useful for
getting the closing parenthesis of an argument list aligned
automatically.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Clean-ups, , Other Electric Commands, Auto-newline Insertion
@comment node-name, next, previous, up
@subsection Clean-ups
@cindex clean-ups
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@dfn{Clean-ups} are mechanisms complementary to colon and brace hanging.
On the surface, it would seem that clean-ups overlap the functionality
provided by the @code{c-hanging-*-alist} variables. Clean-ups are
however used to adjust code ``after-the-fact,'' i.e. to adjust the
whitespace in constructs after they are typed.
Most of the clean-ups are only applicable to counteract automatically
inserted newlines, and will therefore only have any effect if the
auto-newline minor mode is turned on. Others will work all the time.
@vindex c-cleanup-list
@vindex cleanup-list (c-)
@cindex literal
You can configure @ccmode{}'s clean-ups by setting the style variable
@code{c-cleanup-list}, which is a list of clean-up symbols. By default,
@ccmode{} cleans up only the @code{scope-operator} construct, which is
necessary for proper C++ support. Note that clean-ups are only
performed when the construct does not occur within a literal
(@pxref{Auto-newline Insertion}), and when there is nothing but
whitespace appearing between the individual components of the construct.
These are the clean-ups that only are active in the auto-newline minor
mode:
@itemize @bullet
@item
@code{brace-else-brace} --- Clean up @samp{@} else @{} constructs by
placing the entire construct on a single line. Clean-up occurs when the
open brace after the @samp{else} is typed. So for example, this:
@example
@group
void spam(int i)
@{
if( i==7 )
@{
dosomething();
@}
else
@{
@end group
@end example
@noindent
appears like this after the open brace is typed:
@example
@group
void spam(int i)
@{
if( i==7 ) @{
dosomething();
@} else @{
@end group
@end example
@item
@code{brace-elseif-brace} --- Similar to the @code{brace-else-brace}
clean-up, but this cleans up @samp{@} else if (...) @{} constructs. For
example:
@example
@group
void spam(int i)
@{
if( i==7 )
@{
dosomething();
@}
else if( i==3 )
@{
@end group
@end example
@noindent
appears like this after the open parenthesis is typed:
@example
@group
void spam(int i)
@{
if( i==7 ) @{
dosomething();
@} else if( i==3 )
@{
@end group
@end example
@noindent
and like this after the open brace is typed:
@example
@group
void spam(int i)
@{
if( i==7 ) @{
dosomething();
@} else if( i==3 ) @{
@end group
@end example
@item
@code{brace-catch-brace} --- Analogous to @code{brace-elseif-brace}, but
cleans up @samp{@} catch (...) @{} in C++ and Java mode.
@item
@code{empty-defun-braces} --- Clean up braces following a top-level
function or class definition that contains no body. Clean up occurs
when the closing brace is typed. Thus the following:
@example
@group
class Spam
@{
@}
@end group
@end example
@noindent
is transformed into this when the close brace is typed:
@example
@group
class Spam
@{@}
@end group
@end example
@item
@code{defun-close-semi} --- Clean up the terminating semi-colon on
top-level function or class definitions when they follow a close
brace. Clean up occurs when the semi-colon is typed.
So for example, the following:
@example
@group
class Spam
@{
@}
;
@end group
@end example
@noindent
is transformed into this when the semi-colon is typed:
@example
@group
class Spam
@{
@};
@end group
@end example
@item
@code{list-close-comma} --- Clean up commas following braces in array
and aggregate initializers. Clean up occurs when the comma is typed.
@item
@code{scope-operator} --- Clean up double colons which may designate a
C++ scope operator split across multiple lines@footnote{Certain C++
constructs introduce ambiguous situations, so @code{scope-operator}
clean-ups may not always be correct. This usually only occurs when
scoped identifiers appear in switch label tags.}. Clean up occurs when
the second colon is typed. You will always want @code{scope-operator}
in the @code{c-cleanup-list} when you are editing C++ code.
@end itemize
The following clean-ups are always active when they occur on
@code{c-cleanup-list}, and are thus not affected by the auto-newline
minor mode:
@itemize @bullet
@item
@code{space-before-funcall} --- Insert a space between the function name
and the opening parenthesis of a function call. This produces function
calls in the style mandated by the GNU coding standards,
e.g. @samp{signal (SIGINT, SIG_IGN)} and @samp{abort ()}. Clean up
occurs when the opening parenthesis is typed.
@item
@code{compact-empty-funcall} --- Clean up any space between the function
name and the opening parenthesis of a function call that have no
arguments. This is typically used together with
@code{space-before-funcall} if you prefer the GNU function call style
for functions with arguments but think it looks ugly when it's only an
empty parenthesis pair. I.e. you will get @samp{signal (SIGINT,
SIG_IGN)}, but @samp{abort()}. Clean up occurs when the closing
parenthesis is typed.
@end itemize
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Hungry-deletion of Whitespace, , Auto-newline Insertion, Minor Modes
@comment node-name, next, previous, up
@section Hungry-deletion of Whitespace
@cindex hungry-deletion of whitespace
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Hungry deletion of whitespace, or as it more commonly called,
@dfn{hungry-delete mode}, is a simple feature that some people find
extremely useful. In fact, you might find yourself wanting
hungry-delete in @strong{all} your editing modes!
@kindex DEL
@kindex Backspace
In a nutshell, when hungry-delete mode is enabled, hitting the
@key{Backspace} key@footnote{I say ``hit the @key{Backspace} key'' but
what I really mean is ``when Emacs receives the @code{BackSpace} key
event.'' The difference usually isn't significant to most users, but
advanced users will realize that under window systems such as X, any
physical key (keycap) on the keyboard can be configured to generate any
keysym, and thus any Emacs key event. Also, the use of Emacs on TTYs
will affect which keycap generates which key event. From a pedantic
point of view, here we are only concerned with the key event that
Emacs receives.} will consume all preceding whitespace, including
newlines and tabs. This can really cut down on the number of
@key{Backspace}'s you have to type if, for example you made a mistake on
the preceding line.
@findex c-electric-backspace
@findex electric-backspace (c-)
@vindex c-backspace-function
@vindex backspace-function (c-)
@findex c-electric-delete
@findex electric-delete (c-)
@vindex c-delete-function
@vindex delete-function (c-)
@cindex literal
@findex backward-delete-char-untabify
By default, when you hit the @key{Backspace} key @ccmode{} runs the
command @code{c-electric-backspace}, which deletes text in the backwards
direction. When deleting a single character, or when @key{Backspace} is
hit in a literal (@pxref{Auto-newline Insertion}), or when hungry-delete
mode is disabled, the function contained in the
@code{c-backspace-function} variable is called with one argument (the
number of characters to delete). This variable is set to
@code{backward-delete-char-untabify} by default.
@vindex delete-key-deletes-forward
@findex delete-char
The default behavior of the @key{Delete} key depends on the flavor of
Emacs you are using. By default in XEmacs 20.3 and beyond, the
@key{Delete} key is bound to @code{c-electric-delete}. You control the
direction that the @key{Delete} key deletes by setting the variable
@code{delete-key-deletes-forward}, a standard XEmacs variable. When
this variable is non-@code{nil} and hungry-delete mode is enabled,
@code{c-electric-delete} will consume all whitespace @emph{following}
point. When @code{delete-key-deletes-forward} is @code{nil}, it deletes
all whitespace @emph{preceding} point@footnote{i.e. it literally calls
@code{c-electric-backspace}.} When deleting a single character, or if
@key{Delete} is hit in a literal, or hungry-delete mode is disabled, the
function contained in @code{c-delete-function} is called with one
argument: the number of characters to delete. This variable is set to
@code{delete-char} by default.
In Emacs 19 or Emacs 20, both the @key{Delete} and @key{Backspace} keys
are bound to @code{c-electric-backspace}, however you can change this by
explicitly binding @code{[delete]}@footnote{E.g. to
@code{c-electric-delete} in your @file{.emacs} file. Note however, that
Emacs 20 does not have a standard variable such as
@code{delete-key-deletes-forward}.}.
XEmacsen older than 20.3 behave similar to Emacs 19 and Emacs 20.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Text Filling and Line Breaking, Commands, Minor Modes, Top
@comment node-name, next, previous, up
@chapter Text Filling and Line Breaking
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Since there's a lot of normal text in comments and string literals,
@ccmode{} provides features to edit these like in text mode. The goal
is to do it as seamlessly as possible, i.e. you can use auto fill mode,
sentence and paragraph movement, paragraph filling, adaptive filling etc
wherever there's a piece of normal text without having to think much
about it. @ccmode{} should keep the indentation, fix the comment line
decorations, and so on, for you. It does that by hooking in on the
different line breaking functions and tuning relevant variables as
necessary.
@vindex c-comment-prefix-regexp
@vindex comment-prefix-regexp (c-)
@cindex comment line prefix
@vindex comment-start
@vindex comment-end
@vindex comment-start-skip
@vindex paragraph-start
@vindex paragraph-separate
@vindex paragraph-ignore-fill-prefix
@vindex adaptive-fill-mode
@vindex adaptive-fill-regexp
@vindex adaptive-fill-first-line-regexp
To make Emacs recognize comments and treat text in them as normal
paragraphs, @ccmode{} makes several standard
variables@footnote{@code{comment-start}, @code{comment-end},
@code{comment-start-skip}, @code{paragraph-start},
@code{paragraph-separate}, @code{paragraph-ignore-fill-prefix},
@code{adaptive-fill-mode}, @code{adaptive-fill-regexp}, and
@code{adaptive-fill-first-line-regexp}.} buffer local and modifies them
according to the language syntax and the style of line decoration that
starts every line in a comment. The style variable
@code{c-comment-prefix-regexp} contains the regexp used to recognize
this @dfn{comment line prefix}. The default is @samp{//+\\|\\**}, which
matches C++ style line comments like
@example
// blah blah
@end example
@noindent
with two or more slashes in front of them, and C style block comments
like
@example
@group
/*
* blah blah
*/
@end group
@end example
@noindent
with zero or more stars at the beginning of every line. If you change
that variable, please make sure it still matches the comment starter
(i.e. @code{//}) of line comments @emph{and} the line prefix inside
block comments. Also note that since @ccmode{} uses the value of
@code{c-comment-prefix-regexp} to set up several other variables at mode
initialization, you need to reinitialize the program mode if you change
it inside a @ccmode{} buffer.
@findex auto-fill-mode
@cindex auto fill mode
@cindex paragraph fill
Line breaks are by default handled (almost) the same regardless whether
they are made by auto fill mode (@pxref{Auto Fill,,, emacs, The Emacs
Editor}), paragraph filling (e.g. with @kbd{M-q}), or explicitly with
@kbd{M-j} or similar methods. In string literals, the new line gets the
same indentation as the previous nonempty line (may be changed with the
@code{string} syntactic symbol). In comments, @ccmode{} uses
@code{c-comment-prefix-regexp} to adapt the line prefix from the other
lines in the comment.
@vindex adaptive-fill-mode
@cindex adaptive fill mode
@ccmode{} uses adaptive fill mode (@pxref{Adaptive Fill,,, emacs, The
Emacs Editor}) to make Emacs correctly keep the line prefix when filling
paragraphs. That also makes Emacs preserve the text indentation
@emph{inside} the comment line prefix. E.g. in the following comment,
both paragraphs will be filled with the left margins kept intact:
@example
@group
/* Make a balanced b-tree of the nodes in the incoming
* stream. But, to quote the famous words of Donald E.
* Knuth,
*
* Beware of bugs in the above code; I have only
* proved it correct, not tried it.
*/
@end group
@end example
@findex c-setup-filladapt
@findex setup-filladapt (c-)
@findex filladapt-mode
@vindex filladapt-mode
@cindex Filladapt mode
It's also possible to use other adaptive filling packages, notably Kyle
E. Jones' Filladapt package@footnote{It's available from
@uref{http://www.wonderworks.com/}. As of version 2.12, it does however
lack a feature that makes it work suboptimally when
@code{c-comment-prefix-regexp} matches the empty string (which it does
by default). A patch for that is available from
@uref{http://cc-mode.sourceforge.net/,, the CC Mode site}.},
which handles things like bulleted lists nicely. There's a convenience
function @code{c-setup-filladapt} that tunes the relevant variables in
Filladapt for use in @ccmode{}. Call it from a mode hook, e.g. with
something like this in your @file{.emacs}:
@example
@group
(defun my-c-mode-common-hook ()
(c-setup-filladapt)
(filladapt-mode 1))
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
@end group
@end example
@vindex c-block-comment-prefix
@vindex block-comment-prefix (c-)
@vindex c-comment-continuation-stars
@vindex comment-continuation-stars (c-)
Normally the comment line prefix inserted for a new line inside a
comment is deduced from other lines in it. However there's one
situation when there's no clue about how the prefix should look, namely
when a block comment is broken for the first time. The string in the
style variable @code{c-block-comment-prefix}@footnote{In versions before
5.26, this variable was called @code{c-comment-continuation-stars}. As
a compatibility measure, @ccmode{} still uses the value on that variable
if it's set.} is used in that case. It defaults to @samp{* }, which
makes a comment
@example
/* Got O(n^2) here, which is a Bad Thing. */
@end example
@noindent
break into
@example
@group
/* Got O(n^2) here,
* which is a Bad Thing. */
@end group
@end example
Note that it won't work to justify the indentation by putting leading
spaces in the @code{c-block-comment-prefix} string, since @ccmode{}
still uses the normal indentation engine to indent the line. Thus, the
right way to fix the indentation is by setting the @code{c} syntactic
symbol. It defaults to @code{c-lineup-C-comments}, which handles the
indentation of most common comment styles, see @ref{Indentation
Functions}.
@vindex c-ignore-auto-fill
@vindex ignore-auto-fill (c-)
When auto fill mode is enabled, @ccmode{} can selectively ignore it
depending on the context the line break would occur in, e.g. to never
break a line automatically inside a string literal. This behavior can
be controlled with the @code{c-ignore-auto-fill} variable. It takes a
list of symbols for the different contexts where auto-filling never
should occur:
@itemize @bullet
@item @code{string} --- Inside a string or character literal.
@item @code{c} --- Inside a C style block comment.
@item @code{c++} --- Inside a C++ style line comment.
@item @code{cpp} --- Inside a preprocessor directive.
@item @code{code} --- Anywhere else, i.e. in normal code.
@end itemize
By default, @code{c-ignore-auto-fill} is set to @code{'(string cpp
code)}, which means that auto-filling only occurs in comments when
auto-fill mode is activated. In literals, it's often desirable to have
explicit control over newlines. In preprocessor directives, the
necessary @samp{\} escape character before the newline is not
automatically inserted, so an automatic line break would produce invalid
code. In normal code, line breaks are normally dictated by some logical
structure in the code rather than the last whitespace character, so
automatic line breaks there will produce poor results in the current
implementation.
The commands that does the actual work follows.
@table @asis
@kindex M-q
@findex c-fill-paragraph
@findex fill-paragraph (c-)
@cindex Javadoc markup
@cindex Pike autodoc markup
@item @kbd{M-q} (@code{c-fill-paragraph})
This is the replacement for @code{fill-paragraph} in @ccmode{}
buffers. It's used to fill multiline string literals and both block and
line style comments. In Java buffers, the Javadoc markup words are
recognized as paragraph starters. The line oriented Pike autodoc markup
words are recognized in the same way in Pike mode.
The function keeps the comment starters and enders of block comments as
they were before the filling. This means that a comment ender on the
same line as the paragraph being filled will be filled with the
paragraph, and one on a line by itself will stay as it is. The comment
starter is handled similarly@footnote{This means that the variables
@code{c-hanging-comment-starter-p} and @code{c-hanging-comment-ender-p},
which controlled this behavior in earlier versions of @ccmode{}, are now
obsolete.}.
@kindex M-j
@findex c-indent-new-comment-line
@findex indent-new-comment-line (c-)
@item @kbd{M-j} (@code{c-indent-new-comment-line})
This is the replacement for @code{indent-new-comment-line}. It breaks
the line at point and indents the new line like the current one.
@vindex comment-multi-line
If inside a comment and @code{comment-multi-line} is non-@code{nil}, the
indentation and line prefix are preserved. If inside a comment and
@code{comment-multi-line} is @code{nil}, a new comment of the same type
is started on the next line and indented as appropriate for comments.
@findex c-context-line-break
@findex context-line-break (c-)
@item @kbd{M-x c-context-line-break}
This is a function that works like @code{indent-new-comment-line} in
comments and @code{newline-and-indent} elsewhere, thus combining those
two in a way that uses each one in the context it's best suited for.
I.e. in comments the comment line prefix and indentation is kept for the
new line, and in normal code it's indented according to context by the
indentation engine.
It's not bound to a key by default, but it's intended to be used on the
@kbd{RET} key. If you like the behavior of @code{newline-and-indent} on
@kbd{RET}, you might consider switching to this function.
@end table
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Commands, Customizing Indentation, Text Filling and Line Breaking, Top
@comment node-name, next, previous, up
@chapter Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@menu
* Indentation Commands::
* Movement Commands::
* Other Commands::
@end menu
See also @ref{Text Filling and Line Breaking}, for commands concerning
that bit.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Indentation Commands, Movement Commands, , Commands
@comment node-name, next, previous,up
@section Indentation Commands
@cindex indentation commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The following list of commands re-indent C constructs. Note that when
you change your coding style, either interactively or through some other
means, your file does @emph{not} automatically get re-indented. You
will need to execute one of the following commands to see the effects of
your changes.
@cindex GNU indent program
Also, variables like @code{c-hanging-*} and @code{c-cleanup-list}
only affect how on-the-fly code is formatted. Changing the
``hanginess'' of a brace and then re-indenting, will not move the brace
to a different line. For this, you're better off getting an external
program like GNU @code{indent}, which will re-arrange brace location,
among other things.
Re-indenting large sections of code can take a long time. When
@ccmode{} reindents a region of code, it is essentially equivalent to
hitting @kbd{TAB} on every line of the region. Especially vulnerable is
code generator output@footnote{In particular, I have had people
complain about the speed with which @code{lex(1)} output is re-indented.
Lex, yacc, and other code generators usually output some pretty
perversely formatted code. Re-indenting such code will be slow.}.
These commands are useful when indenting code:
@table @asis
@kindex TAB
@findex c-indent-command
@findex indent-command (c-)
@item @kbd{TAB} (@code{c-indent-command})
Indents the current line. The actual behavior is controlled by several
variables, described below. See @code{c-tab-always-indent},
@code{c-insert-tab-function}, and @code{indent-tabs-mode}. With a
numeric argument, this command rigidly indents the region, preserving
the relative indentation among the lines.
@kindex M-C-q
@findex c-indent-exp
@findex indent-exp (c-)
@item @kbd{M-C-q} (@code{c-indent-exp})
Indent an entire balanced brace or parenthesis expression. Note that
point must be on the opening brace or parenthesis of the expression you
want to indent.
@kindex C-c C-q
@findex c-indent-defun
@findex indent-defun (c-)
@item @kbd{C-c C-q} (@code{c-indent-defun})
Indents the entire top-level function or class definition encompassing
point. It leaves point unchanged. This function can't be used to
re-indent a nested brace construct, such as a nested class or function,
or a Java method. The top-level construct being re-indented must be
complete, i.e. it must have both a beginning brace and an ending brace.
@kindex M-C-\
@findex indent-region
@item @kbd{M-C-\} (@code{indent-region})
Indents an arbitrary region of code. This is a standard Emacs command,
tailored for C code in a @ccmode{} buffer. Note that of course, point
and mark must delineate the region you want to indent.
@kindex M-C-h
@findex c-mark-function
@findex mark-function (c-)
@item @kbd{M-C-h} (@code{c-mark-function})
While not strictly an indentation command, this is useful for marking
the current top-level function or class definition as the current
region. As with @code{c-indent-defun}, this command operates on
top-level constructs, and can't be used to mark say, a Java method.
@end table
These variables are also useful when indenting code:
@table @code
@vindex c-tab-always-indent
@vindex tab-always-indent (c-)
@kindex TAB
@cindex literal
@item c-tab-always-indent
This variable controls how @kbd{TAB} @code{c-indent-command} operates.
When this variable is @code{t}, @kbd{TAB} always just indents the
current line. When it is @code{nil}, the line is indented only if point
is at the left margin, or on or before the first non-whitespace
character on the line, otherwise some whitespace is inserted. If this
variable is the symbol @code{other}, then some whitespace is inserted
only within strings and comments (literals), an inside preprocessor
directives, but the line is always reindented.
@vindex c-insert-tab-function
@vindex insert-tab-function (c-)
@findex tab-to-tab-stop
@item c-insert-tab-function
When ``some whitespace'' is inserted as described above, what actually
happens is that the function stored in @code{c-insert-tab-function} is
called. Normally, this just inserts a real tab character, or the
equivalent number of spaces, depending on @code{indent-tabs-mode}.
Some people, however, set @code{c-insert-tab-function} to
@code{tab-to-tab-stop} so as to get hard tab stops when indenting.
@vindex indent-tabs-mode
@item indent-tabs-mode
This is a standard Emacs variable that controls how line indentation is
composed. When this variable is non-@code{nil}, then tabs can be used
in a line's indentation, otherwise only spaces can be used.
@vindex c-progress-interval
@vindex progress-interval (c-)
@item c-progress-interval
When indenting large regions of code, this variable controls how often a
progress message is displayed. Set this variable to @code{nil} to
inhibit the progress messages, or set it to an integer which is the
interval in seconds that progress messages are displayed.
@end table
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Movement Commands, Other Commands, Indentation Commands, Commands
@comment node-name, next, previous, up
@section Movement Commands
@cindex movement commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@ccmode{} contains some useful command for moving around in C
code.
@table @asis
@findex c-beginning-of-defun
@findex beginning-of-defun (c-)
@findex beginning-of-defun
@item @kbd{M-x c-beginning-of-defun}
Moves point back to the least-enclosing brace. This function is
analogous to the Emacs built-in command @code{beginning-of-defun},
except it eliminates the constraint that the top-level opening brace
must be in column zero. See @code{beginning-of-defun} for more
information.
Depending on the coding style being used, you might prefer
@code{c-beginning-of-defun} to @code{beginning-of-defun}. If so,
consider binding @kbd{C-M-a} to the former instead. For backwards
compatibility reasons, the default binding remains in effect.
@findex c-end-of-defun
@findex end-of-defun (c-)
@findex end-of-defun
@item @kbd{M-x c-end-of-defun}
Moves point to the end of the current top-level definition. This
function is analogous to the Emacs built-in command @code{end-of-defun},
except it eliminates the constraint that the top-level opening brace of
the defun must be in column zero. See @code{beginning-of-defun} for more
information.
Depending on the coding style being used, you might prefer
@code{c-end-of-defun} to @code{end-of-defun}. If so,
consider binding @kbd{C-M-e} to the former instead. For backwards
compatibility reasons, the default binding remains in effect.
@kindex C-c C-u
@findex c-up-conditional
@findex up-conditional (c-)
@item @kbd{C-c C-u} (@code{c-up-conditional})
Move point back to the containing preprocessor conditional, leaving the
mark behind. A prefix argument acts as a repeat count. With a negative
argument, move point forward to the end of the containing
preprocessor conditional.
@samp{#elif} is treated like @samp{#else} followed by @samp{#if}, so the
function stops at them when going backward, but not when going forward.
@findex c-up-conditional-with-else
@findex up-conditional-with-else (c-)
@item @kbd{M-x c-up-conditional-with-else}
A variety of @code{c-up-conditional} that also stops at @samp{#else}
lines. Normally those lines are ignored.
@findex c-down-conditional
@findex down-conditional (c-)
@item @kbd{M-x c-down-conditional}
Move point forward into the next nested preprocessor conditional,
leaving the mark behind. A prefix argument acts as a repeat count.
With a negative argument, move point backward into the previous
nested preprocessor conditional.
@samp{#elif} is treated like @samp{#else} followed by @samp{#if}, so the
function stops at them when going forward, but not when going backward.
@findex c-down-conditional-with-else
@findex down-conditional-with-else (c-)
@item @kbd{M-x c-down-conditional-with-else}
A variety of @code{c-down-conditional} that also stops at @samp{#else}
lines. Normally those lines are ignored.
@kindex C-c C-p
@findex c-backward-conditional
@findex backward-conditional (c-)
@item @kbd{C-c C-p} (@code{c-backward-conditional})
Move point back over a preprocessor conditional, leaving the mark
behind. A prefix argument acts as a repeat count. With a negative
argument, move forward.
@kindex C-c C-n
@findex c-forward-conditional
@findex forward-conditional (c-)
@item @kbd{C-c C-n} (@code{c-forward-conditional})
Move point forward across a preprocessor conditional, leaving the mark
behind. A prefix argument acts as a repeat count. With a negative
argument, move backward.
@kindex M-a
@findex c-beginning-of-statement
@findex beginning-of-statement (c-)
@item @kbd{M-a} (@code{c-beginning-of-statement})
Move point to the beginning of the innermost C statement. If point is
already at the beginning of a statement, move to the beginning of the
closest preceding statement, even if that means moving into a block (you
can use @kbd{M-C-b} to move over a balanced block). With prefix
argument @var{n}, move back @var{n} @minus{} 1 statements.
If point is within or next to a comment or a string which spans more
than one line, this command moves by sentences instead of statements.
When called from a program, this function takes three optional
arguments: the repetition count, a buffer position limit which is the
farthest back to search for the syntactic context, and a flag saying
whether to do sentence motion in or near comments and multiline strings.
@kindex M-e
@findex c-end-of-statement
@findex end-of-statement (c-)
@item @kbd{M-e} (@code{c-end-of-statement})
Move point to the end of the innermost C statement. If point is at the
end of a statement, move to the end of the next statement, even if it's
inside a nested block (use @kbd{M-C-f} to move to the other side of the
block). With prefix argument @var{n}, move forward @var{n} @minus{} 1
statements.
If point is within or next to a comment or a string which spans more
than one line, this command moves by sentences instead of statements.
When called from a program, this function takes three optional
arguments: the repetition count, a buffer position limit which is the
farthest back to search for the syntactic context, and a flag saying
whether to do sentence motion in or near comments and multiline strings.
@findex c-forward-into-nomenclature
@findex forward-into-nomenclature (c-)
@item @kbd{M-x c-forward-into-nomenclature}
A popular programming style, especially for object-oriented languages
such as C++ is to write symbols in a mixed case format, where the first
letter of each word is capitalized, and not separated by underscores.
E.g. @samp{SymbolsWithMixedCaseAndNoUnderlines}.
This command moves point forward to next capitalized word. With prefix
argument @var{n}, move @var{n} times.
@findex c-backward-into-nomenclature
@findex backward-into-nomenclature (c-)
@item @kbd{M-x c-backward-into-nomenclature}
Move point backward to beginning of the next capitalized
word. With prefix argument @var{n}, move @var{n} times. If
@var{n} is negative, move forward.
@end table
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Other Commands, , Movement Commands, Commands
@comment node-name, next, previous, up
@section Other Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@ccmode{} contains a few other useful commands:
@table @asis
@kindex C-c :
@findex c-scope-operator
@findex scope-operator (c-)
@item @kbd{C-c :} (@code{c-scope-operator})
In C++, it is also sometimes desirable to insert the double-colon scope
operator without performing the electric behavior of colon insertion.
@kbd{C-c :} does just this.
@kindex C-c C-\
@findex c-backslash-region
@findex backslash-region (c-)
@item @kbd{C-c C-\} (@code{c-backslash-region})
This function is handy when editing macros split over several lines by
ending each line with a backslash. It inserts and aligns, or deletes
these end-of-line backslashes in the current region.
@vindex c-backslash-column
@vindex backslash-column (c-)
With no prefix argument, it inserts any missing backslashes and aligns
them to the column specified by the @code{c-backslash-column} style
variable. With a prefix argument, it deletes any backslashes.
The function does not modify blank lines at the start of the region. If
the region ends at the start of a line, it always deletes the backslash
(if any) at the end of the previous line.
@end table
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Customizing Indentation, Syntactic Symbols, Commands, Top
@comment node-name, next, previous, up
@chapter Customizing Indentation
@cindex customizing indentation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-offsets-alist
@vindex offsets-alist (c-)
The style variable @code{c-offsets-alist} contains the mappings between
syntactic symbols and the offsets to apply for those symbols. It's set
at mode initialization from a @emph{style} you may specify. Styles are
groupings of syntactic symbol offsets and other style variable values.
Most likely, you'll find that one of the pre-defined styles will suit
your needs. @xref{Styles}, for an explanation of how to set up named
styles.
Only syntactic symbols not already bound on @code{c-offsets-alist} will
be set from styles. This means that any association you set on it, be
it before or after mode initialization, will not be changed. The
@code{c-offsets-alist} variable may therefore be used from e.g. the
Customization interface@footnote{Available in Emacs 20 and later, and
XEmacs 19.15 and later.} to easily change indentation offsets without
having to bother about styles. Initially @code{c-offsets-alist} is
empty, so that all syntactic symbols are set by the style system.
@kindex C-c C-o
@findex c-set-offset
@findex set-offset (c-)
You can use the command @kbd{C-c C-o} (@code{c-set-offset}) as the way
to set offsets, both interactively and from your mode
hook@footnote{Obviously, you use the key binding interactively, and the
function call programmatically!}.
@vindex c-basic-offset
@vindex basic-offset (c-)
The offset associated with any particular syntactic symbol can be any of
an integer, a function or lambda expression, a variable name, a vector,
a list, or one of the following symbols: @code{+}, @code{-}, @code{++},
@code{--}, @code{*}, or @code{/}.
Those last special symbols describe an offset in multiples of the value
of the style variable @code{c-basic-offset}. By defining a style's
indentation in terms of this fundamental variable, you can change the
amount of whitespace given to an indentation level while maintaining the
same basic shape of your code. Here are the values that the special
symbols correspond to:
@table @code
@item +
@code{c-basic-offset} times 1
@item -
@code{c-basic-offset} times -1
@item ++
@code{c-basic-offset} times 2
@item --
@code{c-basic-offset} times -2
@item *
@code{c-basic-offset} times 0.5
@item /
@code{c-basic-offset} times -0.5
@end table
@cindex indentation functions
When a function is used as offset, it's called an @dfn{indentation
function}. Such functions are useful when more context than just the
syntactic symbol is needed to get the desired indentation.
@xref{Indentation Functions}, and @ref{Custom Indentation Functions},
for details about them.
If the offset is a vector, its first element sets the absolute
indentation column, which will override any relative indentation.
@vindex c-strict-syntax-p
@vindex strict-syntax-p (c-)
The offset can also be a list, in which case it is evaluated recursively
using the semantics described above. The first element of the list that
returns a non-@code{nil} value succeeds and the evaluation stops. If
none of the list elements return a non-@code{nil} value, then an offset
of 0 (zero) is used@footnote{There is however a variable
@code{c-strict-syntax-p} that, when set to non-@code{nil}, will cause an
error to be signalled in that case. It's now considered obsolete since
it doesn't work well with some of the alignment functions that now
returns @code{nil} instead of zero to be more usable in lists. You
should therefore leave @code{c-strict-syntax-p} set to @code{nil}.}.
So, for example, because most of the default offsets are defined in
terms of @code{+}, @code{-}, and @code{0}, if you like the general
indentation style, but you use 4 spaces instead of 2 spaces per level,
you can probably achieve your style just by changing
@code{c-basic-offset} like so@footnote{You can try this interactively in
a C buffer by typing the text that appears in italics.}:
@example
@emph{M-x set-variable RET}
Set variable: @emph{c-basic-offset RET}
Set c-basic-offset to value: @emph{4 RET}
@end example
@noindent
This would change
@example
@group
int add( int val, int incr, int doit )
@{
if( doit )
@{
return( val + incr );
@}
return( val );
@}
@end group
@end example
@noindent
to
@example
@group
int add( int val, int incr, int doit )
@{
if( doit )
@{
return( val + incr );
@}
return( val );
@}
@end group
@end example
To change indentation styles more radically, you will want to change the
offsets associated with other syntactic symbols. First, I'll show you
how to do that interactively, then I'll describe how to make changes to
your @file{.emacs} file so that your changes are more permanent.
@menu
* Interactive Customization::
* Permanent Customization::
* Hooks::
* Styles::
* Advanced Customizations::
@end menu
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Interactive Customization, Permanent Customization, , Customizing Indentation
@comment node-name, next, previous, up
@section Interactive Customization
@cindex interactive customization
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
As an example of how to customize indentation, let's change the
style of this example@footnote{In this an subsequent examples, the
original code is formatted using the @samp{gnu} style unless otherwise
indicated. @xref{Styles}.}:
@example
@group
1: int add( int val, int incr, int doit )
2: @{
3: if( doit )
4: @{
5: return( val + incr );
6: @}
7: return( val );
8: @}
@end group
@end example
@noindent
to:
@example
@group
1: int add( int val, int incr, int doit )
2: @{
3: if( doit )
4: @{
5: return( val + incr );
6: @}
7: return( val );
8: @}
@end group
@end example
In other words, we want to change the indentation of braces that open a
block following a condition so that the braces line up under the
conditional, instead of being indented. Notice that the construct we
want to change starts on line 4. To change the indentation of a line,
we need to see which syntactic components affect the offset calculations
for that line. Hitting @kbd{C-c C-s} on line 4 yields:
@example
((substatement-open . 44))
@end example
@noindent
so we know that to change the offset of the open brace, we need to
change the indentation for the @code{substatement-open} syntactic
symbol. To do this interactively, just hit @kbd{C-c C-o}. This prompts
you for the syntactic symbol to change, providing a reasonable default.
In this case, the default is @code{substatement-open}, which is just the
syntactic symbol we want to change!
After you hit return, @ccmode{} will then prompt you for the new
offset value, with the old value as the default. The default in this
case is @samp{+}, but we want no extra indentation so enter
@samp{0} and @kbd{RET}. This will associate the offset 0 with the
syntactic symbol @code{substatement-open}.
To check your changes quickly, just hit @kbd{C-c C-q}
(@code{c-indent-defun}) to reindent the entire function. The example
should now look like:
@example
@group
1: int add( int val, int incr, int doit )
2: @{
3: if( doit )
4: @{
5: return( val + incr );
6: @}
7: return( val );
8: @}
@end group
@end example
Notice how just changing the open brace offset on line 4 is all we
needed to do. Since the other affected lines are indented relative to
line 4, they are automatically indented the way you'd expect. For more
complicated examples, this may not always work. The general approach to
take is to always start adjusting offsets for lines higher up in the
file, then re-indent and see if any following lines need further
adjustments.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Permanent Customization, Hooks, Interactive Customization, Customizing Indentation
@comment node-name, next, previous, up
@section Permanent Customization
@cindex permanent customization
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
To make your changes permanent, you need to add some lisp code to your
@file{.emacs} file. @ccmode{} supports many different ways to be
configured, from the straightforward way by setting variables globally
in @file{.emacs} or in the Customization interface, to the complex and
precisely controlled way by using styles and hook functions.
The simplest way of customizing @ccmode{} permanently is to set the
variables in your @file{.emacs} with @code{setq} and similar commands.
So to make the setting of @code{substatement-open} permanent, add this
to the @file{.emacs} file:
@example
@group
(require 'cc-mode)
(c-set-offset 'substatement-open 0)
@end group
@end example
The @code{require} line is only needed once in the beginning to make
sure @ccmode{} is loaded so that the @code{c-set-offset} function is
defined.
You can also use the more user friendly Customization interface, but
this manual does not cover how that works.
Variables set like this at the top level in @file{.emacs} take effect in
all @ccmode{} buffers, regardless of language. The indentation style
related variables, e.g. @code{c-basic-offset}, that you don't set this
way get their value from the style system (@pxref{Styles}), and they
therefore depend on the setting of @code{c-default-style}. Note that if
you use Customize, this means that the greyed-out default values
presented there might not be the ones you actually get, since the actual
values depend on the style, which may very well be different for
different languages.
If you want to make more advanced configurations, e.g. language-specific
customization, global variable settings isn't enough. For that you can
use the language hooks, see @ref{Hooks}, and/or the style system, see
@ref{Styles}.
@vindex c-style-variables-are-local-p
@vindex style-variables-are-local-p (c-)
By default, all style variables are global, so that every buffer will
share the same style settings. This is fine if you primarily edit one
style of code, but if you edit several languages and want to use
different styles for them, you need finer control by making the style
variables buffer local. The recommended way to do this is to set the
variable @code{c-style-variables-are-local-p} to @code{t}. The
variables will be made buffer local when @ccmode{} is activated in a
buffer for the first time in the Emacs session. Note that once the
style variables are made buffer local, they cannot be made global again,
without restarting Emacs.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Hooks, Styles, Permanent Customization, Customizing Indentation
@comment node-name, next, previous, up
@section Hooks
@cindex hooks
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-mode-common-hook
@vindex mode-common-hook (c-)
@vindex c-mode-hook
@vindex c++-mode-hook
@vindex objc-mode-hook
@vindex java-mode-hook
@vindex idl-mode-hook
@vindex pike-mode-hook
@vindex c-initialization-hook
@vindex initialization-hook (c-)
@ccmode{} provides several hooks that you can use to customize the mode
according to your coding style. Each language mode has its own hook,
adhering to standard Emacs major mode conventions. There is also one
general hook and one package initialization hook:
@itemize @bullet
@item
@code{c-mode-hook} --- For C buffers only.
@item
@code{c++-mode-hook} --- For C++ buffers only.
@item
@code{objc-mode-hook} --- For Objective-C buffers only.
@item
@code{java-mode-hook} --- For Java buffers only.
@item
@code{idl-mode-hook} --- For CORBA IDL buffers only.
@item
@code{pike-mode-hook} --- For Pike buffers only.
@item
@code{c-mode-common-hook} --- Common across all languages.
@item
@code{c-initialization-hook} --- Hook run only once per Emacs session,
when @ccmode{} is initialized.
@end itemize
The language hooks get run as the last thing when you enter that
language mode. The @code{c-mode-common-hook} is run by all supported
modes @emph{before} the language specific hook, and thus can contain
customizations that are common across all languages. Most of the
examples in this section will assume you are using the common hook.
Note that all the language-specific mode setup that CC Mode does is done
prior to both @code{c-mode-common-hook} and the language specific hook.
That includes installing the indentation style, which can be mode
specific (and also is by default for Java mode). Thus, any style
settings done in @code{c-mode-common-hook} will override whatever
language-specific style is chosen by @code{c-default-style}.
Here's a simplified example of what you can add to your @file{.emacs}
file to do things whenever any @ccmode{} language is edited. See the
Emacs manuals for more information on customizing Emacs via hooks.
@xref{Sample .emacs File}, for a more complete sample @file{.emacs}
file.
@example
@group
(defun my-c-mode-common-hook ()
;; my customizations for all of c-mode and related modes
(no-case-fold-search)
)
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
@end group
@end example
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Styles, Advanced Customizations, Hooks, Customizing Indentation
@comment node-name, next, previous, up
@section Styles
@cindex styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Most people only need to edit code formatted in just a few well-defined
and consistent styles. For example, their organization might impose a
``blessed'' style that all its programmers must conform to. Similarly,
people who work on GNU software will have to use the GNU coding style.
Some shops are more lenient, allowing a variety of coding styles, and as
programmers come and go, there could be a number of styles in use. For
this reason, @ccmode{} makes it convenient for you to set up logical
groupings of customizations called @dfn{styles}, associate a single name
for any particular style, and pretty easily start editing new or
existing code using these styles.
@cindex style variables
The variables that the style system affect are called @dfn{style
variables}. They are handled specially in several ways:
@itemize @bullet
@item
Style variables are by default global variables, i.e. they have the same
value in all Emacs buffers. However, they can instead be made always
buffer local by setting @code{c-style-variables-are-local-p} to
non-@code{nil} before @ccmode{} is initialized.
@vindex c-old-style-variable-behavior
@vindex old-style-variable-behavior (c-)
@item
The default value of any style variable (with two exceptions --- see
below) is the special symbol @code{set-from-style}. Variables that are
still set to that symbol when a @ccmode{} buffer is initialized will be
set according to the current style, otherwise they will keep their
current value@footnote{This is a big change from versions of @ccmode{}
earlier than 5.26, where such settings would get overridden by the style
system unless special precautions were taken. That was changed since it
was counterintuitive and confusing, especially to novice users. If your
configuration depends on the old overriding behavior, you can set the
variable @code{c-old-style-variable-behavior} to non-@code{nil}.}.
Note that when we talk about the ``default value'' for a style variable,
we don't mean the @code{set-from-style} symbol that all style variables
are set to initially, but instead the value it will get at mode
initialization when neither a style nor a global setting has set its
value.
The style variable @code{c-offsets-alist} is handled a little
differently from the other style variables. It's an association list,
and is thus by default set to the empty list, @code{nil}. When the
style system is initialized, any syntactic symbols already on it are
kept --- only the missing ones are filled in from the chosen style.
The style variable @code{c-special-indent-hook} is also handled in a
special way. Styles may only add more functions on this hook, so the
global settings on it are always preserved@footnote{This did not change
in version 5.26.}.
@item
The global settings of style variables get captured in the special
@code{user} style, which is used as the base for all the other styles.
@xref{Built-in Styles}, for details.
@end itemize
The style variables are:
@code{c-basic-offset},
@code{c-comment-only-line-offset},
@code{c-block-comment-prefix},
@code{c-comment-prefix-regexp},
@code{c-cleanup-list},
@code{c-hanging-braces-alist},
@code{c-hanging-colons-alist},
@code{c-hanging-semi&comma-criteria},
@code{c-backslash-column},
@code{c-special-indent-hook},
@code{c-label-minimum-indentation}, and
@code{c-offsets-alist}.
@menu
* Built-in Styles::
* Adding Styles::
* File Styles::
@end menu
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Built-in Styles, Adding Styles, , Styles
@comment node-name, next, previous, up
@subsection Built-in Styles
@cindex built-in styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
If you're lucky, one of @ccmode{}'s built-in styles might be just
what you're looking for. These include:
@itemize @bullet
@cindex GNU style
@item
@code{gnu} --- Coding style blessed by the Free Software Foundation
for C code in GNU programs.
@cindex K&R style
@item
@code{k&r} --- The classic Kernighan and Ritchie style for C code.
@cindex BSD style
@item
@code{bsd} --- Also known as ``Allman style'' after Eric Allman.
@cindex Whitesmith style
@item
@code{whitesmith} --- Popularized by the examples that came with
Whitesmiths C, an early commercial C compiler.
@cindex Stroustrup style
@item
@code{stroustrup} --- The classic Stroustrup style for C++ code.
@cindex Ellemtel style
@item
@code{ellemtel} --- Popular C++ coding standards as defined by
``Programming in C++, Rules and Recommendations,'' Erik Nyquist and Mats
Henricson, Ellemtel@footnote{This document is available at
@uref{http://www.doc.ic.ac.uk/lab/cplus/c++.rules/} among other
places.}.
@cindex Linux style
@item
@code{linux} --- C coding standard for Linux (the kernel).
@cindex Python style
@item
@code{python} --- C coding standard for Python extension
modules@footnote{Python is a high level scripting language with a C/C++
foreign function interface. For more information, see
@uref{http://www.python.org/}.}.
@cindex Java style
@findex java-mode
@item
@code{java} --- The style for editing Java code. Note that the default
value for @code{c-default-style} installs this style when you enter
@code{java-mode}.
@cindex User style
@item
@code{user} --- This is a special style for several reasons. First, the
@ccmode{} customizations you do by using either the Customization
interface, or by writing @code{setq}'s at the top level of your
@file{.emacs} file, will be captured in the @code{user} style. Also,
all other styles implicitly inherit their settings from @code{user}
style. This means that for any styles you add via @code{c-add-style}
(@pxref{Adding Styles}) you need only define the differences between
your new style and @code{user} style.
@end itemize
@vindex c-default-style
@vindex default-style (c-)
The default style in all newly created buffers is @code{gnu}, but you
can change this by setting variable @code{c-default-style}. Although
the @code{user} style is not the default style, any style variable
settings you do with the Customization interface or on the top level in
your @file{.emacs} file will by default override the style system, so
you don't need to set @code{c-default-style} to @code{user} to see the
effect of these settings.
@code{c-default-style} takes either a style name string, or an
association list of major mode symbols to style names. Thus you can
control exactly which default style is used for which @ccmode{} language
mode. Here are the rules:
@vindex c-style-alist
@vindex style-alist (c-)
@vindex c-mode-common-hook
@vindex mode-common-hook (c-)
@enumerate
@item
When @code{c-default-style} is a string, it must be an existing style
name as found in @code{c-style-alist}. This style is then used for all
modes.
@item
When @code{c-default-style} is an association list, the current major
mode is looked up to find a style name string. In this case, this style
is always used exactly as specified and an error will occur if the named
style does not exist.
@item
If @code{c-default-style} is an association list, but the current major
mode isn't found, then the special symbol @samp{other} is looked up. If
this value is found, the associated style is used.
@item
If @samp{other} is not found, then the @samp{gnu} style is used.
@item
In all cases, the style described in @code{c-default-style} is installed
@emph{before} the language hooks are run, so you can always override
this setting by including an explicit call to @code{c-set-style} in your
language mode hook, or in @code{c-mode-common-hook}.
@end enumerate
@findex c-set-style
@findex set-style (c-)
@kindex C-c .
If you'd like to experiment with these built-in styles you can simply
type the following in a @ccmode{} buffer:
@example
@group
@kbd{C-c . @var{STYLE-NAME} RET}
@end group
@end example
@noindent
@kbd{C-c .} runs the command @code{c-set-style}. Note that all style
names are case insensitive, even the ones you define.
Setting a style in this way does @emph{not} automatically re-indent your
file. For commands that you can use to view the effect of your changes,
see @ref{Commands}.
@vindex c-indentation-style
@vindex indentation-style (c-)
Note that for BOCM compatibility, @samp{gnu} is the default style, and
any non-style based customizations you make (i.e. in
@code{c-mode-common-hook} in your @file{.emacs} file) will be based on
@samp{gnu} style unless you set @code{c-default-style} or do a
@code{c-set-style} as the first thing in your hook. The variable
@code{c-indentation-style} always contains the buffer's current style
name, as a string.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Adding Styles, File Styles, Built-in Styles, Styles
@comment node-name, next, previous, up
@subsection Adding Styles
@cindex adding styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-style-alist
@vindex style-alist (c-)
@findex c-add-style
@findex add-style (c-)
If none of the built-in styles is appropriate, you'll probably want to
add a new @dfn{style definition}. Styles are kept in the
@code{c-style-alist} variable, but you should never modify this variable
directly. Instead, @ccmode{} provides the function
@code{c-add-style} that you can use to easily add new styles or change
existing styles. This function takes two arguments, a @var{stylename}
string, and an association list @var{description} of style
customizations. If @var{stylename} is not already in
@code{c-style-alist}, the new style is added, otherwise the style is
changed to the new @var{description}.
This function also takes an optional third argument, which if
non-@code{nil}, automatically applies the new style to the current
buffer.
@comment TBD: The next paragraph is bogus. I really need to better
@comment document adding styles, including setting up inherited styles.
The sample @file{.emacs} file provides a concrete example of how a new
style can be added and automatically set. @xref{Sample .emacs File}.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node File Styles, , Adding Styles, Styles
@comment node-name, next, previous, up
@subsection File Styles
@cindex file styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@cindex local variables
The Emacs manual describes how you can customize certain variables on a
per-file basis by including a @dfn{Local Variable} block at the end of
the file. So far, you've only seen a functional interface to @ccmode{}
customization, which is highly inconvenient for use in a Local Variable
block. @ccmode{} provides two variables that make it easier for you to
customize your style on a per-file basis.
@vindex c-file-style
@vindex file-style (c-)
@vindex c-file-offsets
@vindex file-offsets (c-)
The variable @code{c-file-style} can be set to a style name string.
When the file is visited, @ccmode{} will automatically set the
file's style to this style using @code{c-set-style}.
Another variable, @code{c-file-offsets}, takes an association list
similar to what is allowed in @code{c-offsets-alist}. When the file is
visited, @ccmode{} will automatically institute these offsets using
@code{c-set-offset}.
Note that file style settings (i.e. @code{c-file-style}) are applied
before file offset settings (i.e. @code{c-file-offsets}). Also, if
either of these are set in a file's local variable section, all the
style variable values are made local to that buffer.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Advanced Customizations, , Styles, Customizing Indentation
@comment node-name, next, previous, up
@section Advanced Customizations
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-style-alist
@vindex style-alist (c-)
For most users, @ccmode{} will support their coding styles with
very little need for more advanced customizations. Usually, one of the
standard styles defined in @code{c-style-alist} will do the trick. At
most, perhaps one of the syntactic symbol offsets will need to be
tweaked slightly, or maybe @code{c-basic-offset} will need to be
changed. However, some styles require a more flexible framework for
customization, and one of the real strengths of @ccmode{} is that
the syntactic analysis model provides just such a framework. This allows
you to implement custom indentation calculations for situations not
handled by the mode directly.
@menu
* Custom Indentation Functions::
* Custom Brace and Colon Hanging::
* Customizing Semi-colons and Commas::
* Other Special Indentations::
@end menu
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Custom Indentation Functions, Custom Brace and Colon Hanging, , Advanced Customizations
@comment node-name, next, previous, up
@subsection Custom Indentation Functions
@cindex custom indentation functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The most flexible way to customize @ccmode{} is by writing custom
indentation functions, and associating them with specific syntactic
symbols (@pxref{Syntactic Symbols}). @ccmode{} itself uses indentation
functions to provide more sophisticated indentation, for example when
lining up C++ stream operator blocks:
@example
@group
1: void main(int argc, char**)
2: @{
3: cout << "There were "
4: << argc
5: << "arguments passed to the program"
6: << endl;
7: @}
@end group
@end example
In this example, lines 4 through 6 are assigned the @code{stream-op}
syntactic symbol. Here, @code{stream-op} has an offset of @code{+}, and
with a @code{c-basic-offset} of 2, you can see that lines 4 through 6
are simply indented two spaces to the right of line 3. But perhaps we'd
like @ccmode{} to be a little more intelligent so that it aligns
all the @samp{<<} symbols in lines 3 through 6. To do this, we have
to write a custom indentation function which finds the column of first
stream operator on the first line of the statement. Here is sample
lisp code implementing this:
@example
@group
(defun c-lineup-streamop (langelem)
;; lineup stream operators
(save-excursion
(let* ((relpos (cdr langelem))
(curcol (progn (goto-char relpos)
(current-column))))
(re-search-forward "<<\\|>>" (c-point 'eol) 'move)
(goto-char (match-beginning 0))
(- (current-column) curcol))))
@end group
@end example
@noindent
Indentation functions take a single argument, which is a syntactic
component cons cell (@pxref{Syntactic Analysis}). The function returns
an integer offset value that will be added to the running total
indentation for the line. Note that what actually gets returned is the
difference between the column that the first stream operator is on, and
the column of the buffer relative position passed in the function's
argument. Remember that @ccmode{} automatically adds in the column of
the component's relative buffer position and we don't the column offset
added in twice.
The function should return @code{nil} if it's used in a situation where
it doesn't want to do any decision. If the function is used in a list
expression (@pxref{Customizing Indentation}), that will cause @ccmode{}
to go on and check the next entry in the list.
@cindex stream-op syntactic symbol
@findex c-lineup-streamop
@findex lineup-streamop (c-)
Now, to associate the function @code{c-lineup-streamop} with the
@code{stream-op} syntactic symbol, we can add something like the
following to our @code{c++-mode-hook}@footnote{It probably makes more
sense to add this to @code{c++-mode-hook} than @code{c-mode-common-hook}
since stream operators are only relevant for C++.}:
@example
(c-set-offset 'stream-op 'c-lineup-streamop)
@end example
Now the function looks like this after re-indenting (using @kbd{C-c
C-q}):
@example
@group
1: void main(int argc, char**)
2: @{
3: cout << "There were "
4: << argc
5: << " arguments passed to the program"
6: << endl;
7: @}
@end group
@end example
Custom indentation functions can be as simple or as complex as you like,
and any syntactic symbol that appears in @code{c-offsets-alist} can have
a custom indentation function associated with it.
@ccmode{} comes with an extensive set of predefined indentation
functions, not all of which are used by the default styles. So there's
a good chance the function you want already exists. @xref{Indentation
Functions}, for a list of them. If you have written an indentation
function that you think is generally useful, you're very welcome to
contribute it; please contact @email{bug-cc-mode@@gnu.org}.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Custom Brace and Colon Hanging, Customizing Semi-colons and Commas, Custom Indentation Functions, Advanced Customizations
@comment node-name, next, previous, up
@subsection Custom Brace and Colon Hanging
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-hanging-braces-alist
@vindex hanging-braces-alist (c-)
Syntactic symbols aren't the only place where you can customize
@ccmode{} with the lisp equivalent of callback functions. Brace
``hanginess'' can also be determined by custom functions associated with
syntactic symbols on the @code{c-hanging-braces-alist} style variable.
Remember that @var{ACTION}'s are typically a list containing some
combination of the symbols @code{before} and @code{after}
(@pxref{Hanging Braces}). However, an @var{ACTION} can also be a
function which gets called when a brace matching that syntactic symbol
is entered.
@cindex customizing brace hanging
These @var{ACTION} functions are called with two arguments: the
syntactic symbol for the brace, and the buffer position at which the
brace was inserted. The @var{ACTION} function is expected to return a
list containing some combination of @code{before} and @code{after},
including neither of them (i.e. @code{nil}). This return value has the
normal brace hanging semantics.
As an example, @ccmode{} itself uses this feature to dynamically
determine the hanginess of braces which close ``do-while''
constructs:
@example
@group
void do_list( int count, char** atleast_one_string )
@{
int i=0;
do @{
handle_string( atleast_one_string[i] );
i++;
@} while( i < count );
@}
@end group
@end example
@findex c-snug-do-while
@findex snug-do-while (c-)
@ccmode{} assigns the @code{block-close} syntactic symbol to the
brace that closes the @code{do} construct, and normally we'd like the
line that follows a @code{block-close} brace to begin on a separate
line. However, with ``do-while'' constructs, we want the
@code{while} clause to follow the closing brace. To do this, we
associate the @code{block-close} symbol with the @var{ACTION} function
@code{c-snug-do-while}:
@example
(defun c-snug-do-while (syntax pos)
"Dynamically calculate brace hanginess for do-while statements.
Using this function, `while' clauses that end a `do-while' block will
remain on the same line as the brace that closes that block.
See `c-hanging-braces-alist' for how to utilize this function as an
ACTION associated with `block-close' syntax."
(save-excursion
(let (langelem)
(if (and (eq syntax 'block-close)
(setq langelem (assq 'block-close c-syntactic-context))
(progn (goto-char (cdr langelem))
(if (= (following-char) ?@{)
(forward-sexp -1))
(looking-at "\\<do\\>[^_]")))
'(before)
'(before after)))))
@end example
This function simply looks to see if the brace closes a ``do-while''
clause and if so, returns the list @samp{(before)} indicating
that a newline should be inserted before the brace, but not after it.
In all other cases, it returns the list @samp{(before after)} so
that the brace appears on a line by itself.
@vindex c-syntactic-context
@vindex syntactic-context (c-)
During the call to the brace hanging @var{ACTION} function, the variable
@code{c-syntactic-context} is bound to the full syntactic analysis list.
@cindex customizing colon hanging
@vindex c-hanging-colon-alist
@vindex hanging-colon-alist (c-)
Note that for symmetry, colon hanginess should be customizable by
allowing function symbols as @var{ACTION}s on the
@code{c-hanging-colon-alist} style variable. Since no use has actually
been found for this feature, it isn't currently implemented!
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Customizing Semi-colons and Commas, Other Special Indentations, Custom Brace and Colon Hanging, Advanced Customizations
@comment node-name, next, previous, up
@subsection Customizing Semi-colons and Commas
@cindex customizing semi-colons and commas
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-hanging-semi&comma-criteria
@vindex hanging-semi&comma-criteria (c-)
You can also customize the insertion of newlines after semi-colons and
commas, when the auto-newline minor mode is enabled (@pxref{Minor
Modes}). This is controlled by the style variable
@code{c-hanging-semi&comma-criteria}, which contains a list of functions
that are called in the order they appear. Each function is called with
zero arguments, and is expected to return one of the following values:
@itemize @bullet
@item
non-@code{nil} --- A newline is inserted, and no more functions from the
list are called.
@item
@code{stop} --- No more functions from the list are called, but no
newline is inserted.
@item
@code{nil} --- No determination is made, and the next function in the
list is called.
@end itemize
If every function in the list is called without a determination being
made, then no newline is added. The default value for this variable is a
list containing a single function which inserts newlines only after
semi-colons which do not appear inside parenthesis lists (i.e. those
that separate @code{for}-clause statements).
@findex c-semi&comma-no-newlines-before-nonblanks
@findex semi&comma-no-newlines-before-nonblanks (c-)
Here's an example of a criteria function, provided by @ccmode{}, that
will prevent newlines from being inserted after semicolons when there is
a non-blank following line. Otherwise, it makes no determination. To
use, add this to the front of the @code{c-hanging-semi&comma-criteria}
list.
@example
@group
(defun c-semi&comma-no-newlines-before-nonblanks ()
(save-excursion
(if (and (eq last-command-char ?\;)
(zerop (forward-line 1))
(not (looking-at "^[ \t]*$")))
'stop
nil)))
@end group
@end example
@findex c-semi&comma-inside-parenlist
@findex c-semi&comma-no-newlines-for-oneline-inliners
@findex semi&comma-inside-parenlist (c-)
@findex semi&comma-no-newlines-for-oneline-inliners (c-)
The function @code{c-semi&comma-inside-parenlist} is what prevents
newlines from being inserted inside the parenthesis list of @code{for}
statements. In addition to
@code{c-semi&comma-no-newlines-before-nonblanks} described above,
@ccmode{} also comes with the criteria function
@code{c-semi&comma-no-newlines-for-oneline-inliners}, which suppresses
newlines after semicolons inside one-line inline method definitions
(i.e. in C++ or Java).
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Other Special Indentations, , Customizing Semi-colons and Commas, Advanced Customizations
@comment node-name, next, previous, up
@subsection Other Special Indentations
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-label-minimum-indentation
@vindex label-minimum-indentation (c-)
In @samp{gnu} style (@pxref{Built-in Styles}), a minimum indentation
is imposed on lines inside top-level constructs. This minimum
indentation is controlled by the style variable
@code{c-label-minimum-indentation}. The default value for this variable
is 1.
@vindex c-special-indent-hook
@vindex special-indent-hook (c-)
One other customization variable is available in @ccmode{}: The style
variable @code{c-special-indent-hook}. This is a standard hook variable
that is called after every line is indented by @ccmode{}. You can use
it to do any special indentation or line adjustments your style
dictates, such as adding extra indentation to constructors or destructor
declarations in a class definition, etc. Note however, that you should
not change point or mark inside your @code{c-special-indent-hook}
functions (i.e. you'll probably want to wrap your function in a
@code{save-excursion}).
Setting @code{c-special-indent-hook} in your style definition is handled
slightly differently than other variables. In your style definition,
you should set the value for
@code{c-special-indent-hook} to a function or list of functions, which
will be appended to @code{c-special-indent-hook} using @code{add-hook}.
That way, the current setting for the buffer local value of
@code{c-special-indent-hook} won't be overridden.
@kindex M-;
@findex indent-for-comment
@vindex c-indent-comments-syntactically-p
@vindex indent-comments-syntactically-p (c-)
@vindex comment-column
Normally, the standard Emacs command @kbd{M-;}
(@code{indent-for-comment}) will indent comment only lines to
@code{comment-column}. Some users however, prefer that @kbd{M-;} act
just like @kbd{TAB} for purposes of indenting comment-only lines;
i.e. they want the comments to always indent as they would for normal
code, regardless of whether @kbd{TAB} or @kbd{M-;} were used. This
behavior is controlled by the variable
@code{c-indent-comments-syntactically-p}. When @code{nil} (the
default), @kbd{M-;} indents comment-only lines to @code{comment-column},
otherwise, they are indented just as they would be if @kbd{TAB} were
typed.
Note that this has no effect for comment lines that are inserted with
@kbd{M-;} at the end of regular code lines. These comments will always
start at @code{comment-column}.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Syntactic Symbols, Indentation Functions, Customizing Indentation, Top
@comment node-name, next, previous, up
@chapter Syntactic Symbols
@cindex syntactic symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@vindex c-offsets-alist
@vindex offsets-alist (c-)
Here is a complete list of the recognized syntactic symbols as described
in the @code{c-offsets-alist} style variable, along with a brief
description. More detailed descriptions follow.
@table @code
@item string
Inside a multi-line string.
@item c
Inside a multi-line C style block comment.
@item defun-open
Brace that opens a top-level function definition.
@item defun-close
Brace that closes a top-level function definition.
@item defun-block-intro
The first line in a top-level defun.
@item class-open
Brace that opens a class definition.
@item class-close
Brace that closes a class definition.
@item inline-open
Brace that opens an in-class inline method.
@item inline-close
Brace that closes an in-class inline method.
@item func-decl-cont
The region between a function definition's argument list and the
function opening brace (excluding K&R argument declarations). In C, you
cannot put anything but whitespace and comments in this region, however
in C++ and Java, @code{throws} declarations and other things can appear
here.
@item knr-argdecl-intro
First line of a K&R C argument declaration.
@item knr-argdecl
Subsequent lines in a K&R C argument declaration.
@item topmost-intro
The first line in a ``topmost'' definition.
@item topmost-intro-cont
Topmost definition continuation lines.
@item member-init-intro
First line in a member initialization list.
@item member-init-cont
Subsequent member initialization list lines.
@item inher-intro
First line of a multiple inheritance list.
@item inher-cont
Subsequent multiple inheritance lines.
@item block-open
Statement block open brace.
@item block-close
Statement block close brace.
@item brace-list-open
Open brace of an enum or static array list.
@item brace-list-close
Close brace of an enum or static array list.
@item brace-list-intro
First line in an enum or static array list.
@item brace-list-entry
Subsequent lines in an enum or static array list.
@item brace-entry-open
Subsequent lines in an enum or static array list where the line begins
with an open brace.
@item statement
A statement.
@item statement-cont
A continuation of a statement.
@item statement-block-intro
The first line in a new statement block.
@item statement-case-intro
The first line in a case block.
@item statement-case-open
The first line in a case block that starts with a brace.
@item substatement
The first line after a conditional or loop construct.
@item substatement-open
The brace that opens a substatement block.
@item case-label
A @code{case} or @code{default} label.
@item access-label
C++ access control label.
@item label
Any non-special C label.
@item do-while-closure
The @code{while} line that ends a @code{do}-@code{while} construct.
@item else-clause
The @code{else} line of an @code{if}-@code{else} construct.
@item catch-clause
The @code{catch} or @code{finally} (in Java) line of a
@code{try}-@code{catch} construct.
@item comment-intro
A line containing only a comment introduction.
@item arglist-intro
The first line in an argument list.
@item arglist-cont
Subsequent argument list lines when no arguments follow on the same line
as the arglist opening paren.
@item arglist-cont-nonempty
Subsequent argument list lines when at least one argument follows on the
same line as the arglist opening paren.
@item arglist-close
The solo close paren of an argument list.
@item stream-op
Lines continuing a stream operator (C++ only).
@item inclass
The line is nested inside a class definition.
@item cpp-macro
The start of a C preprocessor macro definition.
@item cpp-macro-cont
Subsequent lines of a multi-line C preprocessor macro definition.
@item friend
A C++ friend declaration.
@item objc-method-intro
The first line of an Objective-C method. definition.
@item objc-method-args-cont
Lines continuing an Objective-C method. definition
@item objc-method-call-cont
Lines continuing an Objective-C method call.
@item extern-lang-open
Brace that opens an external language block.
@item extern-lang-close
Brace that closes an external language block.
@item inextern-lang
Analogous to @code{inclass} syntactic symbol, but used inside external
language blocks (e.g. @code{extern "C" @{}).
@item namespace-open
Brace that opens a C++ namespace block.
@item namespace-close
Brace that closes a C++ namespace block.
@item innamespace
Analogous to @code{inextern-lang} syntactic symbol, but used inside C++
namespace blocks.
@item template-args-cont
C++ template argument list continuations.
@item inlambda
Analogous to @code{inclass} syntactic symbol, but used inside lambda
(i.e. anonymous) functions. Only used in Pike mode.
@item lambda-intro-cont
Lines continuing the header of a lambda function, i.e. between the
@code{lambda} keyword and the function body. Only used in Pike mode.
@item inexpr-statement
A statement block inside an expression. The gcc C extension of this is
recognized. It's also used for the special functions that takes a
statement block as an argument in Pike.
@item inexpr-class
A class definition inside an expression. This is used for anonymous
classes in Java. It's also used for anonymous array initializers in
Java.
@end table
@cindex -open syntactic symbols
@cindex -close syntactic symbols
Most syntactic symbol names follow a general naming convention. When a
line begins with an open or close brace, the syntactic symbol will
contain the suffix @code{-open} or @code{-close} respectively.
@cindex -intro syntactic symbols
@cindex -cont syntactic symbols
@cindex -block-intro syntactic symbols
Usually, a distinction is made between the first line that introduces a
construct and lines that continue a construct, and the syntactic symbols
that represent these lines will contain the suffix @code{-intro} or
@code{-cont} respectively. As a sub-classification of this scheme, a
line which is the first of a particular brace block construct will
contain the suffix @code{-block-intro}.
Let's look at some examples to understand how this works. Remember that
you can check the syntax of any line by using @kbd{C-c C-s}.
@example
@group
1: void
2: swap( int& a, int& b )
3: @{
4: int tmp = a;
5: a = b;
6: b = tmp;
7: int ignored =
8: a + b;
9: @}
@end group
@end example
@cindex topmost-intro syntactic symbol
@cindex topmost-intro-cont syntactic symbol
@cindex defun-open syntactic symbol
@cindex defun-close syntactic symbol
@cindex defun-block-intro syntactic symbol
Line 1 shows a @code{topmost-intro} since it is the first line that
introduces a top-level construct. Line 2 is a continuation of the
top-level construct introduction so it has the syntax
@code{topmost-intro-cont}. Line 3 shows a @code{defun-open} since it is
the brace that opens a top-level function definition. Line 9 is the
corresponding
@code{defun-close} since it contains the brace that closes the top-level
function definition. Line 4 is a @code{defun-block-intro}, i.e. it is
the first line of a brace-block, enclosed in a
top-level function definition.
@cindex statement syntactic symbol
@cindex statement-cont syntactic symbol
Lines 5, 6, and 7 are all given @code{statement} syntax since there
isn't much special about them. Note however that line 8 is given
@code{statement-cont} syntax since it continues the statement begun
on the previous line.
Here's another example, which illustrates some C++ class syntactic
symbols:
@example
@group
1: class Bass
2: : public Guitar,
3: public Amplifiable
4: @{
5: public:
6: Bass()
7: : eString( new BassString( 0.105 )),
8: aString( new BassString( 0.085 )),
9: dString( new BassString( 0.065 )),
10: gString( new BassString( 0.045 ))
11: @{
12: eString.tune( 'E' );
13: aString.tune( 'A' );
14: dString.tune( 'D' );
15: gString.tune( 'G' );
16: @}
17: friend class Luthier;
18: @}
@end group
@end example
@cindex class-open syntactic symbol
@cindex class-close syntactic symbol
As in the previous example, line 1 has the @code{topmost-intro} syntax.
Here however, the brace that opens a C++ class definition on line 4 is
assigned the @code{class-open} syntax. Note that in C++, classes,
structs, and unions are essentially equivalent syntactically (and are
very similar semantically), so replacing the @code{class} keyword in the
example above with @code{struct} or @code{union} would still result in a
syntax of @code{class-open} for line 4 @footnote{This is the case even
for C and Objective-C. For consistency, structs in all supported
languages are syntactically equivalent to classes. Note however that
the keyword @code{class} is meaningless in C and Objective-C.}.
Similarly, line 18 is assigned @code{class-close} syntax.
@cindex inher-intro syntactic symbol
@cindex inher-cont syntactic symbol
Line 2 introduces the inheritance list for the class so it is assigned
the @code{inher-intro} syntax, and line 3, which continues the
inheritance list is given @code{inher-cont} syntax.
@cindex access-label syntactic symbol
@cindex inclass syntactic symbol
Hitting @kbd{C-c C-s} on line 5 shows the following analysis:
@example
@group
@code{((inclass . 58) (access-label . 67))}
@end group
@end example
@noindent
The primary syntactic symbol for this line is @code{access-label} as
this a label keyword that specifies access protection in C++. However,
because this line is also a top-level construct inside a class
definition, the analysis actually shows two syntactic symbols. The
other syntactic symbol assigned to this line is @code{inclass}.
Similarly, line 6 is given both @code{inclass} and @code{topmost-intro}
syntax:
@example
@group
@code{((inclass . 58) (topmost-intro . 60))}
@end group
@end example
@cindex member-init-intro syntactic symbol
@cindex member-init-cont syntactic symbol
Line 7 introduces a C++ member initialization list and as such is given
@code{member-init-intro} syntax. Note that in this case it is
@emph{not} assigned @code{inclass} since this is not considered a
top-level construct. Lines 8 through 10 are all assigned
@code{member-init-cont} since they continue the member initialization
list started on line 7.
@cindex in-class inline methods
@cindex inline-open syntactic symbol
@cindex inline-close syntactic symbol
Line 11's analysis is a bit more complicated:
@example
@group
@code{((inclass . 58) (inline-open))}
@end group
@end example
This line is assigned a syntax of both @code{inline-open} and
@code{inclass} because it opens an @dfn{in-class} C++ inline method
definition. This is distinct from, but related to, the C++ notion of an
inline function in that its definition occurs inside an enclosing class
definition, which in C++ implies that the function should be inlined.
If though, the definition of the @code{Bass} constructor appeared
outside the class definition, the construct would be given the
@code{defun-open} syntax, even if the keyword @code{inline} appeared
before the method name, as in:
@example
@group
class Bass
: public Guitar,
public Amplifiable
@{
public:
Bass();
@}
inline
Bass::Bass()
: eString( new BassString( 0.105 )),
aString( new BassString( 0.085 )),
dString( new BassString( 0.065 )),
gString( new BassString( 0.045 ))
@{
eString.tune( 'E' );
aString.tune( 'A' );
dString.tune( 'D' );
gString.tune( 'G' );
@}
@end group
@end example
@cindex friend syntactic symbol
Returning to the previous example, line 16 is given @code{inline-close}
syntax, while line 12 is given @code{defun-block-open} syntax, and lines
13 through 15 are all given @code{statement} syntax. Line 17 is
interesting in that its syntactic analysis list contains three
elements:
@example
@code{((friend) (inclass . 58) (topmost-intro . 380))}
@end example
The @code{friend} syntactic symbol is a modifier that typically does not
have a relative buffer position.
Template definitions introduce yet another syntactic symbol:
@example
@group
1: ThingManager <int,
2: Framework::Callback *,
3: Mutex> framework_callbacks;
@end group
@end example
Here, line 1 is analyzed as a @code{topmost-intro}, but lines 2 and 3
are both analyzed as @code{template-args-cont} lines.
Here is another (totally contrived) example which illustrates how syntax
is assigned to various conditional constructs:
@example
@group
1: void spam( int index )
2: @{
3: for( int i=0; i<index; i++ )
4: @{
5: if( i == 10 )
6: @{
7: do_something_special();
8: @}
9: else
10: do_something( i );
11: @}
12: do @{
13: another_thing( i-- );
14: @}
15: while( i > 0 );
16: @}
@end group
@end example
@noindent
Only the lines that illustrate new syntactic symbols will be discussed.
@cindex substatement-open syntactic symbol
@cindex substatement-block-intro syntactic symbol
@cindex block-close syntactic symbol
Line 4 has a brace which opens a conditional's substatement block. It
is thus assigned @code{substatement-open} syntax, and since line 5 is
the first line in the substatement block, it is assigned
@code{substatement-block-intro} syntax. Lines 6 and 7 are assigned
similar syntax. Line 8 contains the brace that closes the inner
substatement block. It is given the syntax @code{block-close},
as are lines 11 and 14.
@cindex else-clause syntactic symbol
@cindex catch-clause syntactic symbol
Line 9 is a little different --- since it contains the keyword
@code{else} matching the @code{if} statement introduced on line 5, it is
given the @code{else-clause} syntax. The @code{try}-@code{catch}
constructs in C++ and Java are treated this way too, with the only
difference that the @code{catch}, and in Java also @code{finally}, is
marked with @code{catch-clause}.
@cindex substatement syntactic symbol
Line 10 is also slightly different. Because @code{else} is considered a
conditional introducing keyword @footnote{The list of conditional
keywords are (in C, C++, Objective-C, Java, and Pike): @code{for},
@code{if}, @code{do}, @code{else}, @code{while}, and @code{switch}. C++
and Java have two additional conditional keywords: @code{try} and
@code{catch}. Java also has the @code{finally} and @code{synchronized}
keywords.}, and because the following substatement is not a brace block,
line 10 is assigned the @code{substatement} syntax.
@cindex do-while-closure syntactic symbol
One other difference is seen on line 15. The @code{while} construct
that closes a @code{do} conditional is given the special syntax
@code{do-while-closure} if it appears on a line by itself. Note that if
the @code{while} appeared on the same line as the preceding close brace,
that line would have been assigned @code{block-close} syntax instead.
Switch statements have their own set of syntactic symbols. Here's an
example:
@example
@group
1: void spam( enum Ingredient i )
2: @{
3: switch( i ) @{
4: case Ham:
5: be_a_pig();
6: break;
7: case Salt:
8: drink_some_water();
9: break;
10: default:
11: @{
12: what_is_it();
13: break;
14: @}
15: @}
14: @}
@end group
@end example
@cindex case-label syntactic symbol
@cindex statement-case-intro syntactic symbol
@cindex statement-case-open syntactic symbol
Here, lines 4, 7, and 10 are all assigned @code{case-label} syntax,
while lines 5 and 8 are assigned @code{statement-case-intro}. Line 11
is treated slightly differently since it contains a brace that opens a
block --- it is given @code{statement-case-open} syntax.
@cindex brace lists
There are a set of syntactic symbols that are used to recognize
constructs inside of brace lists. A brace list is defined as an
@code{enum} or aggregate initializer list, such as might statically
initialize an array of structs. The three special aggregate constructs
in Pike, @code{(@{ @})}, @code{([ ])} and @code{(< >)}, are treated as
brace lists too. An example:
@example
@group
1: static char* ingredients[] =
2: @{
3: "Ham",
4: "Salt",
5: NULL
6: @}
@end group
@end example
@cindex brace-list-open syntactic symbol
@cindex brace-list-intro syntactic symbol
@cindex brace-list-close syntactic symbol
@cindex brace-list-entry syntactic symbol
Following convention, line 2 in this example is assigned
@code{brace-list-open} syntax, and line 3 is assigned
@code{brace-list-intro} syntax. Likewise, line 6 is assigned
@code{brace-list-close} syntax. Lines 4 and 5 however, are assigned
@code{brace-list-entry} syntax, as would all subsequent lines in this
initializer list.
@cindex brace-entry-open syntactic symbol
Your static initializer might be initializing nested structures, for
example:
@example
@group
1: struct intpairs[] =
2: @{
3: @{ 1, 2 @},
4: @{
5: 3,
6: 4
7: @}
8: @{ 1,
9: 2 @},
10: @{ 3, 4 @}
11: @}
@end group
@end example
Here, you've already seen the analysis of lines 1, 2, 3, and 11. On
line 4, things get interesting; this line is assigned
@code{brace-entry-open} syntactic symbol because it's a bracelist entry
line that starts with an open brace. Lines 5 and 6 (and line 9) are
pretty standard, and line 7 is a @code{brace-list-close} as you'd
expect. Once again, line 8 is assigned as @code{brace-entry-open} as is
line 10.
External language definition blocks also have their own syntactic
symbols. In this example:
@example
@group
1: extern "C"
2: @{
3: int thing_one( int );
4: int thing_two( double );
5: @}
@end group
@end example
@cindex extern-lang-open syntactic symbol
@cindex extern-lang-close syntactic symbol
@cindex inextern-lang syntactic symbol
@cindex inclass syntactic symbol
@noindent
line 2 is given the @code{extern-lang-open} syntax, while line 5 is given
the @code{extern-lang-close} syntax. The analysis for line 3 yields:
@code{((inextern-lang) (topmost-intro . 14))}, where
@code{inextern-lang} is a modifier similar in purpose to @code{inclass}.
Similarly, C++ namespace constructs have their own associated syntactic
symbols. In this example:
@example
@group
1: namespace foo
2: @{
3: void xxx() @{@}
4: @}
@end group
@end example
@cindex namespace-open syntactic symbol
@cindex namespace-close syntactic symbol
@cindex innamespace syntactic symbol
@noindent
line 2 is given the @code{namespace-open} syntax, while line 4 is given
the @code{namespace-close} syntax. The analysis for line 3 yields:
@code{((innamespace) (topmost-intro . 17))}, where @code{innamespace} is
a modifier similar in purpose to @code{inextern-lang} and @code{inclass}.
A number of syntactic symbols are associated with parenthesis lists,
a.k.a argument lists, as found in function declarations and function
calls. This example illustrates these:
@example
@group
1: void a_function( int line1,
2: int line2 );
3:
4: void a_longer_function(
5: int line1,
6: int line2
7: );
8:
9: void call_them( int line1, int line2 )
10: @{
11: a_function(
12: line1,
13: line2
14: );
15:
16: a_longer_function( line1,
17: line2 );
18: @}
@end group
@end example
@cindex arglist-intro syntactic symbol
@cindex arglist-close syntactic symbol
Lines 5 and 12 are assigned @code{arglist-intro} syntax since they are
the first line following the open parenthesis, and lines 7 and 14 are
assigned @code{arglist-close} syntax since they contain the parenthesis
that closes the argument list.
@cindex arglist-cont-nonempty syntactic symbol
@cindex arglist-cont syntactic symbol
Lines that continue argument lists can be assigned one of two syntactic
symbols. For example, Lines 2 and 17
are assigned @code{arglist-cont-nonempty} syntax. What this means
is that they continue an argument list, but that the line containing the
parenthesis that opens the list is @emph{not empty} following the open
parenthesis. Contrast this against lines 6 and 13 which are assigned
@code{arglist-cont} syntax. This is because the parenthesis that opens
their argument lists is the last character on that line.
Note that there is no @code{arglist-open} syntax. This is because any
parenthesis that opens an argument list, appearing on a separate line,
is assigned the @code{statement-cont} syntax instead.
A few miscellaneous syntactic symbols that haven't been previously
covered are illustrated by this C++ example:
@example
@group
1: void Bass::play( int volume )
2: const
3: @{
4: /* this line starts a multi-line
5: * comment. This line should get `c' syntax */
6:
7: char* a_multiline_string = "This line starts a multi-line \
8: string. This line should get `string' syntax.";
9:
10: note:
11: @{
12: #ifdef LOCK
13: Lock acquire();
14: #endif // LOCK
15: slap_pop();
16: cout << "I played "
17: << "a note\n";
18: @}
19: @}
@end group
@end example
The lines to note in this example include:
@itemize @bullet
@cindex func-decl-cont syntactic symbol
@item
Line 2 is assigned the @code{func-decl-cont} syntax.
@cindex comment-intro syntactic symbol
@item
Line 4 is assigned both @code{defun-block-intro} @emph{and}
@code{comment-intro} syntax.
@cindex c syntactic symbol
@item
Line 5 is assigned @code{c} syntax.
@item
@cindex syntactic whitespace
Line 6 which, even though it contains nothing but whitespace, is
assigned @code{defun-block-intro}. Note that the appearance of the
comment on lines 4 and 5 do not cause line 6 to be assigned
@code{statement} syntax because comments are considered to be
@dfn{syntactic whitespace}, which are ignored when analyzing
code.
@cindex string syntactic symbol
@item
Line 8 is assigned @code{string} syntax.
@cindex label syntactic symbol
@item
Line 10 is assigned @code{label} syntax.
@cindex block-open syntactic symbol
@item
Line 11 is assigned @code{block-open} syntax.
@cindex cpp-macro syntactic symbol
@cindex cpp-macro-cont syntactic symbol
@item
Lines 12 and 14 are assigned @code{cpp-macro} syntax in addition to the
normal syntactic symbols (@code{statement-block-intro} and
@code{statement}, respectively). Normally @code{cpp-macro} is
configured to cancel out the normal syntactic context to make all
preprocessor directives stick to the first column, but that's easily
changed if you want preprocessor directives to be indented like the rest
of the code.
@cindex stream-op syntactic symbol
@item
Line 17 is assigned @code{stream-op} syntax.
@end itemize
@cindex multi-line macros
@cindex syntactic whitespace
Multi-line C preprocessor macros are now (somewhat) supported. At least
@ccmode{} now recognizes the fact that it is inside a multi-line macro,
and it properly skips such macros as syntactic whitespace. In this
example:
@example
@group
1: #define LIST_LOOP(cons, listp) \
2: for (cons = listp; !NILP (cons); cons = XCDR (cons)) \
3: if (!CONSP (cons)) \
4: signal_error ("Invalid list format", listp); \
5: else
@end group
@end example
@noindent
line 1 is given the syntactic symbol @code{cpp-macro}. This first line
of a macro is always given this symbol. The second and subsequent lines
(e.g. lines 2 through 5) are given the @code{cpp-macro-cont} syntactic
symbol, with a relative buffer position pointing to the @code{#} which
starts the macro definition.
In Objective-C buffers, there are three additional syntactic symbols
assigned to various message calling constructs. Here's an example
illustrating these:
@example
@group
1: - (void)setDelegate:anObject
2: withStuff:stuff
3: @{
4: [delegate masterWillRebind:self
5: toDelegate:anObject
6: withExtraStuff:stuff];
7: @}
@end group
@end example
@cindex objc-method-intro syntactic symbol
@cindex objc-method-args-cont syntactic symbol
@cindex objc-method-call-cont syntactic symbol
Here, line 1 is assigned @code{objc-method-intro} syntax, and line 2 is
assigned @code{objc-method-args-cont} syntax. Lines 5 and 6 are both
assigned @code{objc-method-call-cont} syntax.
Java has a concept of anonymous classes, which may look something like
this:
@example
@group
1: public void watch(Observable o) @{
2: o.addObserver(new Observer() @{
3: public void update(Observable o, Object arg) @{
4: history.addElement(arg);
5: @}
6: @});
7: @}
@end group
@end example
@cindex inexpr-class syntactic symbol
The brace following the @code{new} operator opens the anonymous class.
Lines 3 and 6 are assigned the @code{inexpr-class} syntax, besides the
@code{inclass} symbol used in normal classes. Thus, the class will be
indented just like a normal class, with the added indentation given to
@code{inexpr-class}.
There are a few occasions where a statement block may be used inside an
expression. One is in C code using the gcc extension for this, e.g:
@example
@group
1: int res = (@{
2: int y = foo (); int z;
3: if (y > 0) z = y; else z = - y;
4: z;
5: @});
@end group
@end example
@cindex inexpr-statement syntactic symbol
Lines 2 and 5 get the @code{inexpr-statement} syntax, besides the
symbols they'd get in a normal block. Therefore, the indentation put on
@code{inexpr-statement} is added to the normal statement block
indentation.
In Pike code, there are a few other situations where blocks occur inside
statements, as illustrated here:
@example
@group
1: array itgob()
2: @{
3: string s = map (backtrace()[-2][3..],
4: lambda
5: (mixed arg)
6: @{
7: return sprintf ("%t", arg);
8: @}) * ", " + "\n";
9: return catch @{
10: write (s + "\n");
11: @};
12: @}
@end group
@end example
@cindex inlambda syntactic symbol
@cindex lambda-intro-cont syntactic symbol
Lines 4 through 8 contain a lambda function, which @ccmode{} recognizes
by the @code{lambda} keyword. If the function argument list is put
on a line of its own, as in line 5, it gets the @code{lambda-intro-cont}
syntax. The function body is handled as an inline method body, with the
addition of the @code{inlambda} syntactic symbol. This means that line
6 gets @code{inlambda} and @code{inline-open}, and line 8 gets
@code{inline-close}@footnote{You might wonder why it doesn't get
@code{inlambda} too. It's because the closing brace is relative to the
opening brace, which stands on its own line in this example. If the
opening brace was hanging on the previous line, then the closing brace
would get the @code{inlambda} syntax too to be indented correctly.}.
@cindex inexpr-statement syntactic symbol
On line 9, @code{catch} is a special function taking a statement block
as its argument. The block is handled as an in-expression statement
with the @code{inexpr-statement} syntax, just like the gcc extended C
example above. The other similar special function, @code{gauge}, is
handled like this too.
@cindex knr-argdecl-intro syntactic symbol
@cindex knr-argdecl syntactic symbol
Two other syntactic symbols can appear in old style, non-prototyped C
code @footnote{a.k.a. K&R C, or Kernighan & Ritchie C}:
@example
@group
1: int add_three_integers(a, b, c)
2: int a;
3: int b;
4: int c;
5: @{
6: return a + b + c;
7: @}
@end group
@end example
Here, line 2 is the first line in an argument declaration list and so is
given the @code{knr-argdecl-intro} syntactic symbol. Subsequent lines
(i.e. lines 3 and 4 in this example), are given @code{knr-argdecl}
syntax.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Indentation Functions, Performance Issues, Syntactic Symbols, Top
@comment node-name, next, previous, up
@chapter Indentation Functions
@cindex indentation functions
@cindex line-up functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Often there are cases when a simple offset setting on a syntactic symbol
isn't enough to get the desired indentation. Therefore, it's also
possible to use a @dfn{indentation function} (a.k.a. line-up function)
for a syntactic symbol.
@ccmode{} comes with many predefined indentation functions for common
situations. If none of these does what you want, you can write your
own, see @ref{Custom Indentation Functions}. If you do, it's probably a
good idea to start working from one of these predefined functions, they
can be found in the file @file{cc-align.el}.
For every function below there is a ``works with'' list that indicates
which syntactic symbols the function is intended to be used with.
@macro workswith
@emph{Works with:@ }
@end macro
@ifinfo
@unmacro workswith
@macro workswith
Works with:
@end macro
@end ifinfo
@table @code
@findex c-lineup-arglist
@findex lineup-arglist (c-)
@item c-lineup-arglist
Line up the current argument line under the first argument.
@workswith @code{arglist-cont-nonempty}.
@findex c-lineup-arglist-intro-after-paren
@findex lineup-arglist-intro-after-paren (c-)
@item c-lineup-arglist-intro-after-paren
Line up a line just after the open paren of the surrounding paren or
brace block.
@workswith @code{defun-block-intro}, @code{brace-list-intro},
@code{statement-block-intro}, @code{statement-case-intro},
@code{arglist-intro}.
@findex c-lineup-arglist-close-under-paren
@findex lineup-arglist-close-under-paren (c-)
@item c-lineup-arglist-close-under-paren
Set e.g. your @code{arglist-close} syntactic symbol to this line-up
function so that parentheses that close argument lists will line up
under the parenthesis that opened the argument list.
@workswith @code{defun-close}, @code{class-close}, @code{inline-close},
@code{block-close}, @code{brace-list-close}, @code{arglist-close},
@code{extern-lang-close}, @code{namespace-close} (for most of these, a
zero offset will normally produce the same result, though).
@findex c-lineup-close-paren
@findex lineup-close-paren (c-)
@item c-lineup-close-paren
Line up the closing paren under its corresponding open paren if the
open paren is followed by code. If the open paren ends its line, no
indentation is added. E.g:
@example
@group
main (int,
char **
) // c-lineup-close-paren
@end group
@end example
@noindent
and
@example
@group
main (
int, char **
) // c-lineup-close-paren
@end group
@end example
@workswith @code{defun-close}, @code{class-close}, @code{inline-close},
@code{block-close}, @code{brace-list-close}, @code{arglist-close},
@code{extern-lang-close}, @code{namespace-close}.
@findex c-lineup-streamop
@findex lineup-streamop (c-)
@item c-lineup-streamop
Line up C++ stream operators (i.e. @samp{<<} and @samp{>>}).
@workswith @code{stream-op}.
@findex c-lineup-multi-inher
@findex lineup-multi-inher (c-)
@item c-lineup-multi-inher
Line up the classes in C++ multiple inheritance clauses and member
initializers under each other. E.g:
@example
@group
Foo::Foo (int a, int b):
Cyphr (a),
Bar (b) // c-lineup-multi-inher
@end group
@end example
@noindent
and
@example
@group
class Foo
: public Cyphr,
public Bar // c-lineup-multi-inher
@end group
@end example
@noindent
and
@example
@group
Foo::Foo (int a, int b)
: Cyphr (a)
, Bar (b) // c-lineup-multi-inher
@end group
@end example
@workswith @code{inher-cont}, @code{member-init-cont}.
@findex c-lineup-java-inher
@findex lineup-java-inher (c-)
@item c-lineup-java-inher
Line up Java implements and extends declarations. If class names
follows on the same line as the @samp{implements}/@samp{extends}
keyword, they are lined up under each other. Otherwise, they are
indented by adding @code{c-basic-offset} to the column of the keyword.
E.g:
@example
@group
class Foo
extends
Bar // c-lineup-java-inher
<--> c-basic-offset
@end group
@end example
@noindent
and
@example
@group
class Foo
extends Cyphr,
Bar // c-lineup-java-inher
@end group
@end example
@workswith @code{inher-cont}.
@findex c-lineup-java-throws
@findex lineup-java-throws (c-)
@item c-lineup-java-throws
Line up Java throws declarations. If exception names follows on the
same line as the throws keyword, they are lined up under each other.
Otherwise, they are indented by adding @code{c-basic-offset} to the
column of the @samp{throws} keyword. The @samp{throws} keyword itself
is also indented by @code{c-basic-offset} from the function declaration
start if it doesn't hang. E.g:
@example
@group
int foo()
throws // c-lineup-java-throws
Bar // c-lineup-java-throws
<--><--> c-basic-offset
@end group
@end example
@noindent
and
@example
@group
int foo() throws Cyphr,
Bar, // c-lineup-java-throws
Vlod // c-lineup-java-throws
@end group
@end example
@workswith @code{func-decl-cont}.
@findex c-indent-one-line-block
@findex indent-one-line-block (c-)
@item c-indent-one-line-block
Indent a one line block @code{c-basic-offset} extra. E.g:
@example
@group
if (n > 0)
@{m+=n; n=0;@} // c-indent-one-line-block
<--> c-basic-offset
@end group
@end example
@noindent
and
@example
@group
if (n > 0)
@{ // c-indent-one-line-block
m+=n; n=0;
@}
@end group
@end example
The block may be surrounded by any kind of parenthesis characters.
@code{nil} is returned if the line doesn't start with a one line block,
which makes the function usable in list expressions.
@workswith Almost all syntactic symbols, but most useful on the
@code{-open} symbols.
@findex c-indent-multi-line-block
@findex indent-multi-line-block (c-)
@item c-indent-multi-line-block
Indent a multi line block @code{c-basic-offset} extra. E.g:
@example
@group
int *foo[] = @{
NULL,
@{17@}, // c-indent-multi-line-block
@end group
@end example
@noindent
and
@example
@group
int *foo[] = @{
NULL,
@{ // c-indent-multi-line-block
17
@},
<--> c-basic-offset
@end group
@end example
The block may be surrounded by any kind of parenthesis characters.
@code{nil} is returned if the line doesn't start with a multi line
block, which makes the function usable in list expressions.
@workswith Almost all syntactic symbols, but most useful on the
@code{-open} symbols.
@findex c-lineup-C-comments
@findex lineup-C-comments (c-)
@item c-lineup-C-comments
Line up C block comment continuation lines. Various heuristics are used
to handle most of the common comment styles. Some examples:
@example
@group
/* /** /*
* text * text text
*/ */ */
@end group
@group
/* text /* /**
text ** text ** text
*/ */ */
@end group
@group
/**************************************************
* text
*************************************************/
@end group
@vindex comment-start-skip
@group
/**************************************************
Free form text comments:
In comments with a long delimiter line at the
start, the indentation is kept unchanged for lines
that start with an empty comment line prefix. The
delimiter line is whatever matches the
@code{comment-start-skip} regexp.
**************************************************/
@end group
@end example
The style variable @code{c-comment-prefix-regexp} is used to recognize
the comment line prefix, e.g. the @samp{*} that usually starts every
line inside a comment.
@workswith The @code{c} syntactic symbol.
@findex c-lineup-comment
@findex lineup-comment (c-)
@item c-lineup-comment
Line up a comment-only line according to the style variable
@code{c-comment-only-line-offset}. If the comment is lined up with a
comment starter on the previous line, that alignment is preserved.
@vindex c-comment-only-line-offset
@vindex comment-only-line-offset (c-)
@code{c-comment-only-line-offset} specifies the extra offset for the
line. It can contain an integer or a cons cell of the form
@example
(@r{<non-anchored-offset>} . @r{<anchored-offset>})
@end example
@noindent
where @var{non-anchored-offset} is the amount of offset given to
non-column-zero anchored lines, and @var{anchored-offset} is the amount
of offset to give column-zero anchored lines. Just an integer as value
is equivalent to @code{(@r{<value>} . -1000)}.
@workswith @code{comment-intro}.
@findex c-lineup-runin-statements
@findex lineup-runin-statements (c-)
@item c-lineup-runin-statements
Line up statements for coding standards which place the first statement
in a block on the same line as the block opening brace@footnote{Run-in
style doesn't really work too well. You might need to write your own
custom indentation functions to better support this style.}. E.g:
@example
@group
int main()
@{ puts (\"Hello world!\");
return 0; // c-lineup-runin-statements
@}
@end group
@end example
If there is no statement after the opening brace to align with,
@code{nil} is returned. This makes the function usable in list
expressions.
@workswith The @code{statement} syntactic symbol.
@findex c-lineup-math
@findex lineup-math (c-)
@item c-lineup-math
Line up the current line after the equal sign on the first line in the
statement. If there isn't any, indent with @code{c-basic-offset}. If
the current line contains an equal sign too, try to align it with the
first one.
@workswith @code{statement-cont}.
@findex c-lineup-template-args
@findex lineup-template-args (c-)
@item c-lineup-template-args
Line up the arguments of a template argument list under each other, but
only in the case where the first argument is on the same line as the
opening @samp{<}.
To allow this function to be used in a list expression, @code{nil} is
returned if there's no template argument on the first line.
@workswith @code{template-args-cont}.
@findex c-lineup-ObjC-method-call
@findex lineup-ObjC-method-call (c-)
@item c-lineup-ObjC-method-call
For Objective-C code, line up selector args as @code{elisp-mode} does
with function args: go to the position right after the message receiver,
and if you are at the end of the line, indent the current line
c-basic-offset columns from the opening bracket; otherwise you are
looking at the first character of the first method call argument, so
lineup the current line with it.
@workswith @code{objc-method-call-cont}.
@findex c-lineup-ObjC-method-args
@findex lineup-ObjC-method-args (c-)
@item c-lineup-ObjC-method-args
For Objective-C code, line up the colons that separate args. The colon
on the current line is aligned with the one on the first line.
@workswith @code{objc-method-args-cont}.
@findex c-lineup-ObjC-method-args-2
@findex lineup-ObjC-method-args-2 (c-)
@item c-lineup-ObjC-method-args-2
Similar to @code{c-lineup-ObjC-method-args} but lines up the colon on
the current line with the colon on the previous line.
@workswith @code{objc-method-args-cont}.
@findex c-lineup-inexpr-block
@findex lineup-inexpr-block (c-)
@item c-lineup-inexpr-block
This can be used with the in-expression block symbols to indent the
whole block to the column where the construct is started. E.g. for Java
anonymous classes, this lines up the class under the @samp{new} keyword,
and in Pike it lines up the lambda function body under the @samp{lambda}
keyword. Returns @code{nil} if the block isn't part of such a
construct.
@workswith @code{inlambda}, @code{inexpr-statement},
@code{inexpr-class}.
@findex c-lineup-whitesmith-in-block
@findex lineup-whitesmith-in-block (c-)
@item c-lineup-whitesmith-in-block
Line up lines inside a block in Whitesmith style. It's done in a way
that works both when the opening brace hangs and when it doesn't. E.g:
@example
@group
something
@{
foo; // c-lineup-whitesmith-in-block
@}
@end group
@end example
@noindent
and
@example
@group
something @{
foo; // c-lineup-whitesmith-in-block
@}
<--> c-basic-offset
@end group
@end example
In the first case the indentation is kept unchanged, in the second
@code{c-basic-offset} is added.
@workswith @code{defun-close}, @code{defun-block-intro},
@code{block-close}, @code{brace-list-close}, @code{brace-list-intro},
@code{statement-block-intro}, @code{inclass}, @code{inextern-lang},
@code{innamespace}.
@findex c-lineup-dont-change
@findex lineup-dont-change (c-)
@item c-lineup-dont-change
This lineup function makes the line stay at whatever indentation it
already has; think of it as an identity function for lineups. It is
used for @code{cpp-macro-cont} lines.
@workswith Any syntactic symbol.
@end table
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Performance Issues, Limitations and Known Bugs, Indentation Functions, Top
@comment node-name, next, previous, up
@chapter Performance Issues
@cindex performance issues
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
C and its derivative languages are highly complex creatures. Often,
ambiguous code situations arise that require @ccmode{} to scan
large portions of the buffer to determine syntactic context. Such
pathological code@footnote{such as the output of @code{lex(1)}!}
can cause @ccmode{} to perform fairly badly.
This section identifies some of the coding styles to watch out for, and
suggests some workarounds that you can use to improve performance.
Because @ccmode{} has to scan the buffer backwards from the current
insertion point, and because C's syntax is fairly difficult to parse in
the backwards direction, @ccmode{} often tries to find the nearest
position higher up in the buffer from which to begin a forward scan.
The farther this position is from the current insertion point, the
slower the mode gets. Some coding styles can even force @ccmode{}
to scan from the beginning of the buffer for every line of code!
@findex beginning-of-defun
@findex defun-prompt-regexp
One of the simplest things you can do to reduce scan time, is make sure
any brace that opens a top-level construct@footnote{E.g. a function in
C, or outermost class definition in C++ or Java.} always appears in the
leftmost column. This is actually an Emacs constraint, as embodied in
the @code{beginning-of-defun} function which @ccmode{} uses heavily. If
you insist on hanging top-level open braces on the right side of the
line, then you might want to set the variable @code{defun-prompt-regexp}
to something reasonable, however that ``something reasonable'' is
difficult to define, so @ccmode{} doesn't do it for you.
@vindex c-Java-defun-prompt-regexp
@vindex Java-defun-prompt-regexp (c-)
A special note about @code{defun-prompt-regexp} in Java mode: while much
of the early sample Java code seems to encourage a style where the brace
that opens a class is hung on the right side of the line, this is not a
good style to pursue in Emacs. @ccmode{} comes with a variable
@code{c-Java-defun-prompt-regexp} which tries to define a regular
expression usable for this style, but there are problems with it. In
some cases it can cause @code{beginning-of-defun} to hang@footnote{This
has been observed in Emacs 19.34 and XEmacs 19.15.}. For this reason,
it is not used by default, but if you feel adventurous, you can set
@code{defun-prompt-regexp} to it in your mode hook. In any event,
setting and rely on @code{defun-prompt-regexp} will definitely slow
things down anyway because you'll be doing regular expression searches
for every line you indent, so you're probably screwed either way!
@vindex c-enable-xemacs-performance-kludge-p
@vindex enable-xemacs-performance-kludge-p (c-)
Another alternative for XEmacs users, is to set the variable
@code{c-enable-xemacs-performance-kludge-p} to non-@code{nil}. This
tells @ccmode{} to use XEmacs-specific built-in functions which, in some
circumstances, can locate the top-most opening brace much quicker than
@code{beginning-of-defun}. Preliminary testing has shown that for
styles where these braces are hung (e.g. most JDK-derived Java styles),
this hack can improve performance of the core syntax parsing routines
from 3 to 60 times. However, for styles which @emph{do} conform to
Emacs' recommended style of putting top-level braces in column zero,
this hack can degrade performance by about as much. Thus this variable
is set to @code{nil} by default, since the Emacs-friendly styles
should be more common (and
encouraged!). Note that this variable has no effect in Emacs since the
necessary built-in functions don't exist (in Emacs 20.2 or 20.3 as of
this writing 27-Apr-1998).
You will probably notice pathological behavior from @ccmode{} when
working in files containing large amounts of C preprocessor macros.
This is because Emacs cannot skip backwards over these lines as quickly
as it can comments.
@vindex c-recognize-knr-p
@vindex recognize-knr-p (c-)
Previous versions of @ccmode{} had potential performance problems
when recognizing K&R style function argument declarations. This was
because there are ambiguities in the C syntax when K&R style argument
lists are used@footnote{It is hard to distinguish them from top-level
declarations.}. @ccmode{} has adopted BOCM's convention for
limiting the search: it assumes that argdecls are indented at least one
space, and that the function headers are not indented at all. With
current versions of @ccmode{}, user customization of
@code{c-recognize-knr-p} is deprecated. Just don't put argdecls in
column zero!
@cindex @file{cc-lobotomy.el} file
@vindex cc-lobotomy-pith-list
You might want to investigate the speed-ups contained in the
file @file{cc-lobotomy.el}, which comes as part of the @ccmode{}
distribution, but is completely unsupported.
As mentioned previous, @ccmode{} always trades speed for accuracy,
however it is recognized that sometimes you need speed and can sacrifice
some accuracy in indentation. The file @file{cc-lobotomy.el} contains
hacks that will ``dumb down'' @ccmode{} in some specific ways, making
that trade-off of accurancy for speed. I won't go into details of its
use here; you should read the comments at the top of the file, and look
at the variable @code{cc-lobotomy-pith-list} for details.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Limitations and Known Bugs, Frequently Asked Questions, Performance Issues, Top
@comment node-name, next, previous, up
@chapter Limitations and Known Bugs
@cindex limitations
@cindex bugs
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@itemize @bullet
@item
Re-indenting large regions or expressions can be slow.
@findex c-indent-exp
@findex indent-exp (c-)
@item
@code{c-indent-exp} has not been fully optimized. It essentially
equivalent to hitting @kbd{TAB} (@code{c-indent-command}) on every
line. Some information is cached from line to line, but such caching
invariable causes inaccuracies in analysis in some bizarre situations.
@vindex signal-error-on-buffer-boundary
@item
XEmacs versions from 19.15 until (as of this writing 12-Mar-1998) 20.4
contain a variable called @code{signal-error-on-buffer-boundary}. This
was intended as a solution to user interface problems associated with
buffer movement and the @code{zmacs-region} deactivation on errors.
However, setting this variable to a non-default value had the
deleterious side effect of breaking many built-in primitive functions.
Most users will not be affected since they never change the value of
this variable. @strong{Do not set this variable to @code{nil}}; you
will cause serious problems in @ccmode{} and probably other XEmacs
packages! As of at least XEmacs 20.4, the effects this variable tried
to correct have been fixed in other, better ways.
@end itemize
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Frequently Asked Questions, Getting the Latest CC Mode Release, Limitations and Known Bugs, Top
@comment node-name, next, previous, up
@appendix Frequently Asked Questions
@cindex frequently asked questions
@cindex FAQ
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@kindex C-x h
@kindex C-M-\
@kindex C-M-x
@kindex C-M-q
@kindex C-M-u
@kindex RET
@kindex C-j
@quotation
@strong{Q.} @emph{How do I re-indent the whole file?}
@strong{A.} Visit the file and hit @kbd{C-x h} to mark the whole
buffer. Then hit @kbd{C-M-\}.
@sp 1
@strong{Q.} @emph{How do I re-indent the entire function?
@kbd{C-M-x} doesn't work.}
@strong{A.} @kbd{C-M-x} is reserved for future Emacs use.
To re-indent the entire function hit @kbd{C-c C-q}.
@sp 1
@strong{Q.} @emph{How do I re-indent the current block?}
@strong{A.} First move to the brace which opens the block with
@kbd{C-M-u}, then re-indent that expression with
@kbd{C-M-q}.
@sp 1
@strong{Q.} @emph{Why doesn't the @kbd{RET} key indent the new line?}
@strong{A.} Emacs' convention is that @kbd{RET} just adds a newline,
and that @kbd{C-j} adds a newline and indents it. You can make
@kbd{RET} do this too by adding this to your
@code{c-mode-common-hook}:
@example
(define-key c-mode-base-map "\C-m" 'c-context-line-break)
@end example
This is a very common question. If you want this to be the default
behavior, don't lobby me, lobby RMS! @t{:-)}
@sp 1
@strong{Q.} @emph{I put @code{(c-set-offset 'substatement-open 0)}
in my @file{.emacs} file but I get an error saying that
@code{c-set-offset}'s function definition is void.}
@strong{A.} This means that @ccmode{} wasn't loaded into your
Emacs session by the time the @code{c-set-offset} call was reached,
most likely because @ccmode{} is being autoloaded. Instead
of putting the @code{c-set-offset} line in your top-level
@file{.emacs} file, put it in your @code{c-mode-common-hook}, or
simply modify @code{c-offsets-alist} directly:
@example
(setq c-offsets-alist '((substatement-open . 0)))
@end example
@sp 1
@strong{Q.} @emph{How do I make strings, comments, keywords, and other
constructs appear in different colors, or in bold face, etc.?}
@strong{A.} ``Syntax Colorization'' is a standard Emacs feature,
controlled by @code{font-lock-mode}. @ccmode{} does not contain
font-lock definitions for any of its supported languages.
@sp 1
@strong{Q.} @emph{@kbd{M-a} and @kbd{M-e} used to move over entire
balanced brace lists, but now they move into blocks. How do I get the
old behavior back?}
@strong{A.} Use @kbd{C-M-f} and @kbd{C-M-b} to move over balanced brace
blocks. Use @kbd{M-a} and @kbd{M-e} to move by statements, which will
also move into blocks.
@sp 1
@strong{Q.} @emph{Whenever I try to indent a line or type an
``electric'' key such as @kbd{;}, @kbd{@{}, or @kbd{@}}, I get an error
that look like this: @code{Invalid function: (macro . #[...}. What
gives?}
@strong{A.} This is a common error when @ccmode{} hasn't been compiled
correctly, especially under Emacs 19.34@footnote{Technically, it's
because some macros wasn't defined during the compilation, so the byte
compiler put in function calls instead of the macro expansions. Later,
when the interpreter tries to call the macros as functions, it shows
this (somewhat cryptic) error message.}. If you are using the standalone
@ccmode{} distribution, try recompiling it according to the instructions
in the @file{README} file.
@end quotation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Getting the Latest CC Mode Release, Mailing Lists and Submitting Bug Reports, Frequently Asked Questions, Top
@comment node-name, next, previous, up
@appendix Getting the Latest CC Mode Release
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@ccmode{} is standard with all versions of Emacs since 19.34 and of
XEmacs since 19.16.
Due to release schedule skew, it is likely that all of these Emacsen
have old versions of @ccmode{} and so should be upgraded. Access to the
@ccmode{} source code, as well as more detailed information on Emacsen
compatibility, etc. are all available via the Web at:
@example
@group
@uref{http://cc-mode.sourceforge.net/}
@end group
@end example
@emph{Old URLs, including the FTP URLs, should no longer be used.}
There are many files under these directories; you can pick up the entire
distribution (named @code{cc-mode.tar.gz}; a gzip'd tar file), or any of
the individual files, including PostScript documentation.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Mailing Lists and Submitting Bug Reports, Sample .emacs File, Getting the Latest CC Mode Release, Top
@comment node-name, next, previous, up
@appendix Mailing Lists and Submitting Bug Reports
@cindex mailing lists
@cindex reporting bugs
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@kindex C-c C-b
@findex c-submit-bug-report
@findex submit-bug-report (c-)
To report bugs, use the @kbd{C-c C-b} (@code{c-submit-bug-report})
command. This provides vital information we need to reproduce your
problem. Make sure you include a concise, but complete code example.
Please try to boil your example down to just the essential code needed
to reproduce the problem, and include an exact recipe of steps needed to
expose the bug. Be especially sure to include any code that appears
@emph{before} your bug example, if you think it might affect our ability
to reproduce it.
Please try to produce the problem in an Emacs instance without any
customizations loaded (i.e. start it with the @code{-q -no-site-file}
arguments). If it works correctly there, the problem might be caused by
faulty customizations in either your own or your site configuration. In
that case, we'd appreciate if you isolate the Emacs Lisp code that trigs
the bug and include it in your report.
@cindex bug report mailing list
Bug reports are now sent to the following email addresses:
@email{bug-cc-mode@@gnu.org} and @email{bug-gnu-emacs@@gnu.org}; the
latter is mirrored on the Usenet newsgroup @code{gnu.emacs.bug}. You
can send other questions and suggestions (kudos? @t{;-)} to
@email{bug-cc-mode@@gnu.org}.
@cindex announcement mailing list
If you want to get announcements of new @ccmode{} releases, send the
word @emph{subscribe} in the body of a message to
@email{cc-mode-announce-request@@lists.sourceforge.net}. Announcements
will also be posted to the Usenet newsgroups @code{gnu.emacs.sources},
@code{comp.emacs} and @code{comp.emacs.xemacs}.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Sample .emacs File, Concept Index, Mailing Lists and Submitting Bug Reports, Top
@comment node-name, next, previous, up
@appendix Sample .emacs file
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@example
;; Here's a sample .emacs file that might help you along the way. Just
;; copy this region and paste it into your .emacs file. You may want to
;; change some of the actual values.
(defconst my-c-style
'((c-tab-always-indent . t)
(c-comment-only-line-offset . 4)
(c-hanging-braces-alist . ((substatement-open after)
(brace-list-open)))
(c-hanging-colons-alist . ((member-init-intro before)
(inher-intro)
(case-label after)
(label after)
(access-label after)))
(c-cleanup-list . (scope-operator
empty-defun-braces
defun-close-semi))
(c-offsets-alist . ((arglist-close . c-lineup-arglist)
(substatement-open . 0)
(case-label . 4)
(block-open . 0)
(knr-argdecl-intro . -)))
(c-echo-syntactic-information-p . t)
)
"My C Programming Style")
;; offset customizations not in my-c-style
(setq c-offsets-alist '((member-init-intro . ++)))
;; Customizations for all modes in CC Mode.
(defun my-c-mode-common-hook ()
;; add my personal style and set it for the current buffer
(c-add-style "PERSONAL" my-c-style t)
;; other customizations
(setq tab-width 8
;; this will make sure spaces are used instead of tabs
indent-tabs-mode nil)
;; we like auto-newline and hungry-delete
(c-toggle-auto-hungry-state 1)
;; key bindings for all supported languages. We can put these in
;; c-mode-base-map because c-mode-map, c++-mode-map, objc-mode-map,
;; java-mode-map, idl-mode-map, and pike-mode-map inherit from it.
(define-key c-mode-base-map "\C-m" 'c-context-line-break)
)
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
@end example
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Concept Index, Command Index, Sample .emacs File, Top
@comment node-name, next, previous, up
@unnumbered Concept Index
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@printindex cp
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Command Index, Key Index, Concept Index, Top
@comment node-name, next, previous, up
@unnumbered Command Index
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Since most @ccmode{} commands are prepended with the string
@samp{c-}, each appears under its @code{c-@var{<thing>}} name and its
@code{@var{<thing>} (c-)} name.
@iftex
@sp 2
@end iftex
@printindex fn
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Key Index, Variable Index, Command Index, Top
@comment node-name, next, previous, up
@unnumbered Key Index
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@printindex ky
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node Variable Index, , Key Index, Top
@comment node-name, next, previous, up
@unnumbered Variable Index
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Since most @ccmode{} variables are prepended with the string
@samp{c-}, each appears under its @code{c-@var{<thing>}} name and its
@code{@var{<thing>} (c-)} name.
@iftex
@sp 2
@end iftex
@printindex vr
@iftex
@page
@summarycontents
@contents
@end iftex
@bye