------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- G N A T . A W K -- -- -- -- S p e c -- -- -- -- Copyright (C) 2000-2003 Ada Core Technologies, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- This is an AWK-like unit. It provides an easy interface for parsing one -- or more files containing formatted data. The file can be viewed seen as -- a database where each record is a line and a field is a data element in -- this line. In this implementation an AWK record is a line. This means -- that a record cannot span multiple lines. The operating procedure is to -- read files line by line, with each line being presented to the user of -- the package. The interface provides services to access specific fields -- in the line. Thus it is possible to control actions takn on a line based -- on values of some fields. This can be achieved directly or by registering -- callbacks triggered on programmed conditions. -- -- The state of an AWK run is recorded in an object of type session. -- The following is the procedure for using a session to control an -- AWK run: -- -- 1) Specify which session is to be used. It is possible to use the -- default session or to create a new one by declaring an object of -- type Session_Type. For example: -- -- Computers : Session_Type; -- -- 2) Specify how to cut a line into fields. There are two modes: using -- character fields separators or column width. This is done by using -- Set_Fields_Separators or Set_Fields_Width. For example by: -- -- AWK.Set_Field_Separators (";,", Computers); -- -- or by using iterators' Separators parameter. -- -- 3) Specify which files to parse. This is done with Add_File/Add_Files -- services, or by using the iterators' Filename parameter. For -- example: -- -- AWK.Add_File ("myfile.db", Computers); -- -- 4) Run the AWK session using one of the provided iterators. -- -- Parse -- This is the most automated iterator. You can gain control on -- the session only by registering one or more callbacks (see -- Register). -- -- Get_Line/End_Of_Data -- This is a manual iterator to be used with a loop. You have -- complete control on the session. You can use callbacks but -- this is not required. -- -- For_Every_Line -- This provides a mixture of manual/automated iterator action. -- -- Examples of these three approaches appear below -- -- There is many ways to use this package. The following discussion shows -- three approaches, using the three iterator forms, to using this package. -- All examples will use the following file (computer.db): -- -- Pluton;Windows-NT;Pentium III -- Mars;Linux;Pentium Pro -- Venus;Solaris;Sparc -- Saturn;OS/2;i486 -- Jupiter;MacOS;PPC -- -- 1) Using Parse iterator -- -- Here the first step is to register some action associated to a pattern -- and then to call the Parse iterator (this is the simplest way to use -- this unit). The default session is used here. For example to output the -- second field (the OS) of computer "Saturn". -- -- procedure Action is -- begin -- Put_Line (AWK.Field (2)); -- end Action; -- -- begin -- AWK.Register (1, "Saturn", Action'Access); -- AWK.Parse (";", "computer.db"); -- -- -- 2) Using the Get_Line/End_Of_Data iterator -- -- Here you have full control. For example to do the same as -- above but using a specific session, you could write: -- -- Computer_File : Session_Type; -- -- begin -- AWK.Set_Current (Computer_File); -- AWK.Open (Separators => ";", -- Filename => "computer.db"); -- -- -- Display Saturn OS -- -- while not AWK.End_Of_File loop -- AWK.Get_Line; -- -- if AWK.Field (1) = "Saturn" then -- Put_Line (AWK.Field (2)); -- end if; -- end loop; -- -- AWK.Close (Computer_File); -- -- -- 3) Using For_Every_Line iterator -- -- In this case you use a provided iterator and you pass the procedure -- that must be called for each record. You could code the previous -- example could be coded as follows (using the iterator quick interface -- but without using the current session): -- -- Computer_File : Session_Type; -- -- procedure Action (Quit : in out Boolean) is -- begin -- if AWK.Field (1, Computer_File) = "Saturn" then -- Put_Line (AWK.Field (2, Computer_File)); -- end if; -- end Action; -- -- procedure Look_For_Saturn is -- new AWK.For_Every_Line (Action); -- -- begin -- Look_For_Saturn (Separators => ";", -- Filename => "computer.db", -- Session => Computer_File); -- -- Integer_Text_IO.Put -- (Integer (AWK.NR (Session => Computer_File))); -- Put_Line (" line(s) have been processed."); -- -- You can also use a regular expression for the pattern. Let us output -- the computer name for all computer for which the OS has a character -- O in its name. -- -- Regexp : String := ".*O.*"; -- -- Matcher : Regpat.Pattern_Matcher := Regpat.Compile (Regexp); -- -- procedure Action is -- begin -- Text_IO.Put_Line (AWK.Field (2)); -- end Action; -- -- begin -- AWK.Register (2, Matcher, Action'Unrestricted_Access); -- AWK.Parse (";", "computer.db"); -- with Ada.Finalization; with GNAT.Regpat; package GNAT.AWK is Session_Error : exception; -- Raised when a Session is reused but is not closed. File_Error : exception; -- Raised when there is a file problem (see below). End_Error : exception; -- Raised when an attempt is made to read beyond the end of the last -- file of a session. Field_Error : exception; -- Raised when accessing a field value which does not exist. Data_Error : exception; -- Raised when it is not possible to convert a field value to a specific -- type. type Count is new Natural; type Widths_Set is array (Positive range <>) of Positive; -- Used to store a set of columns widths. Default_Separators : constant String := " " & ASCII.HT; Use_Current : constant String := ""; -- Value used when no separator or filename is specified in iterators. type Session_Type is limited private; -- This is the main exported type. A session is used to keep the state of -- a full AWK run. The state comprises a list of files, the current file, -- the number of line processed, the current line, the number of fields in -- the current line... A default session is provided (see Set_Current, -- Current_Session and Default_Session above). ---------------------------- -- Package initialization -- ---------------------------- -- To be thread safe it is not possible to use the default provided -- session. Each task must used a specific session and specify it -- explicitly for every services. procedure Set_Current (Session : Session_Type); -- Set the session to be used by default. This file will be used when the -- Session parameter in following services is not specified. function Current_Session return Session_Type; -- Returns the session used by default by all services. This is the -- latest session specified by Set_Current service or the session -- provided by default with this implementation. function Default_Session return Session_Type; -- Returns the default session provided by this package. Note that this is -- the session return by Current_Session if Set_Current has not been used. procedure Set_Field_Separators (Separators : String := Default_Separators; Session : Session_Type := Current_Session); -- Set the field separators. Each character in the string is a field -- separator. When a line is read it will be split by field using the -- separators set here. Separators can be changed at any point and in this -- case the current line is split according to the new separators. In the -- special case that Separators is a space and a tabulation -- (Default_Separators), fields are separated by runs of spaces and/or -- tabs. procedure Set_FS (Separators : String := Default_Separators; Session : Session_Type := Current_Session) renames Set_Field_Separators; -- FS is the AWK abbreviation for above service. procedure Set_Field_Widths (Field_Widths : Widths_Set; Session : Session_Type := Current_Session); -- This is another way to split a line by giving the length (in number of -- characters) of each field in a line. Field widths can be changed at any -- point and in this case the current line is split according to the new -- field lengths. A line split with this method must have a length equal or -- greater to the total of the field widths. All characters remaining on -- the line after the latest field are added to a new automatically -- created field. procedure Add_File (Filename : String; Session : Session_Type := Current_Session); -- Add Filename to the list of file to be processed. There is no limit on -- the number of files that can be added. Files are processed in the order -- they have been added (i.e. the filename list is FIFO). If Filename does -- not exist or if it is not readable, File_Error is raised. procedure Add_Files (Directory : String; Filenames : String; Number_Of_Files_Added : out Natural; Session : Session_Type := Current_Session); -- Add all files matching the regular expression Filenames in the specified -- directory to the list of file to be processed. There is no limit on -- the number of files that can be added. Each file is processed in -- the same order they have been added (i.e. the filename list is FIFO). -- The number of files (possibly 0) added is returned in -- Number_Of_Files_Added. ------------------------------------- -- Information about current state -- ------------------------------------- function Number_Of_Fields (Session : Session_Type := Current_Session) return Count; pragma Inline (Number_Of_Fields); -- Returns the number of fields in the current record. It returns 0 when -- no file is being processed. function NF (Session : Session_Type := Current_Session) return Count renames Number_Of_Fields; -- AWK abbreviation for above service. function Number_Of_File_Lines (Session : Session_Type := Current_Session) return Count; pragma Inline (Number_Of_File_Lines); -- Returns the current line number in the processed file. It returns 0 when -- no file is being processed. function FNR (Session : Session_Type := Current_Session) return Count renames Number_Of_File_Lines; -- AWK abbreviation for above service. function Number_Of_Lines (Session : Session_Type := Current_Session) return Count; pragma Inline (Number_Of_Lines); -- Returns the number of line processed until now. This is equal to number -- of line in each already processed file plus FNR. It returns 0 when -- no file is being processed. function NR (Session : Session_Type := Current_Session) return Count renames Number_Of_Lines; -- AWK abbreviation for above service. function Number_Of_Files (Session : Session_Type := Current_Session) return Natural; pragma Inline (Number_Of_Files); -- Returns the number of files associated with Session. This is the total -- number of files added with Add_File and Add_Files services. function File (Session : Session_Type := Current_Session) return String; -- Returns the name of the file being processed. It returns the empty -- string when no file is being processed. --------------------- -- Field accessors -- --------------------- function Field (Rank : Count; Session : Session_Type := Current_Session) return String; -- Returns field number Rank value of the current record. If Rank = 0 it -- returns the current record (i.e. the line as read in the file). It -- raises Field_Error if Rank > NF or if Session is not open. function Field (Rank : Count; Session : Session_Type := Current_Session) return Integer; -- Returns field number Rank value of the current record as an integer. It -- raises Field_Error if Rank > NF or if Session is not open. It -- raises Data_Error if the field value cannot be converted to an integer. function Field (Rank : Count; Session : Session_Type := Current_Session) return Float; -- Returns field number Rank value of the current record as a float. It -- raises Field_Error if Rank > NF or if Session is not open. It -- raises Data_Error if the field value cannot be converted to a float. generic type Discrete is (<>); function Discrete_Field (Rank : Count; Session : Session_Type := Current_Session) return Discrete; -- Returns field number Rank value of the current record as a type -- Discrete. It raises Field_Error if Rank > NF. It raises Data_Error if -- the field value cannot be converted to type Discrete. -------------------- -- Pattern/Action -- -------------------- -- AWK defines rules like "PATTERN { ACTION }". Which means that ACTION -- will be executed if PATTERN match. A pattern in this implementation can -- be a simple string (match function is equality), a regular expression, -- a function returning a boolean. An action is associated to a pattern -- using the Register services. -- -- Each procedure Register will add a rule to the set of rules for the -- session. Rules are examined in the order they have been added. type Pattern_Callback is access function return Boolean; -- This is a pattern function pointer. When it returns True the associated -- action will be called. type Action_Callback is access procedure; -- A simple action pointer type Match_Action_Callback is access procedure (Matches : GNAT.Regpat.Match_Array); -- An advanced action pointer used with a regular expression pattern. It -- returns an array of all the matches. See GNAT.Regpat for further -- information. procedure Register (Field : Count; Pattern : String; Action : Action_Callback; Session : Session_Type := Current_Session); -- Register an Action associated with a Pattern. The pattern here is a -- simple string that must match exactly the field number specified. procedure Register (Field : Count; Pattern : GNAT.Regpat.Pattern_Matcher; Action : Action_Callback; Session : Session_Type := Current_Session); -- Register an Action associated with a Pattern. The pattern here is a -- simple regular expression which must match the field number specified. procedure Register (Field : Count; Pattern : GNAT.Regpat.Pattern_Matcher; Action : Match_Action_Callback; Session : Session_Type := Current_Session); -- Same as above but it pass the set of matches to the action -- procedure. This is useful to analyse further why and where a regular -- expression did match. procedure Register (Pattern : Pattern_Callback; Action : Action_Callback; Session : Session_Type := Current_Session); -- Register an Action associated with a Pattern. The pattern here is a -- function that must return a boolean. Action callback will be called if -- the pattern callback returns True and nothing will happen if it is -- False. This version is more general, the two other register services -- trigger an action based on the value of a single field only. procedure Register (Action : Action_Callback; Session : Session_Type := Current_Session); -- Register an Action that will be called for every line. This is -- equivalent to a Pattern_Callback function always returning True. -------------------- -- Parse iterator -- -------------------- procedure Parse (Separators : String := Use_Current; Filename : String := Use_Current; Session : Session_Type := Current_Session); -- Launch the iterator, it will read every line in all specified -- session's files. Registered callbacks are then called if the associated -- pattern match. It is possible to specify a filename and a set of -- separators directly. This offer a quick way to parse a single -- file. These parameters will override those specified by Set_FS and -- Add_File. The Session will be opened and closed automatically. -- File_Error is raised if there is no file associated with Session, or if -- a file associated with Session is not longer readable. It raises -- Session_Error is Session is already open. ----------------------------------- -- Get_Line/End_Of_Data Iterator -- ----------------------------------- type Callback_Mode is (None, Only, Pass_Through); -- These mode are used for Get_Line/End_Of_Data and For_Every_Line -- iterators. The associated semantic is: -- -- None -- callbacks are not active. This is the default mode for -- Get_Line/End_Of_Data and For_Every_Line iterators. -- -- Only -- callbacks are active, if at least one pattern match, the associated -- action is called and this line will not be passed to the user. In -- the Get_Line case the next line will be read (if there is some -- line remaining), in the For_Every_Line case Action will -- not be called for this line. -- -- Pass_Through -- callbacks are active, for patterns which match the associated -- action is called. Then the line is passed to the user. It means -- that Action procedure is called in the For_Every_Line case and -- that Get_Line returns with the current line active. -- procedure Open (Separators : String := Use_Current; Filename : String := Use_Current; Session : Session_Type := Current_Session); -- Open the first file and initialize the unit. This must be called once -- before using Get_Line. It is possible to specify a filename and a set of -- separators directly. This offer a quick way to parse a single file. -- These parameters will override those specified by Set_FS and Add_File. -- File_Error is raised if there is no file associated with Session, or if -- the first file associated with Session is no longer readable. It raises -- Session_Error is Session is already open. procedure Get_Line (Callbacks : Callback_Mode := None; Session : Session_Type := Current_Session); -- Read a line from the current input file. If the file index is at the -- end of the current input file (i.e. End_Of_File is True) then the -- following file is opened. If there is no more file to be processed, -- exception End_Error will be raised. File_Error will be raised if Open -- has not been called. Next call to Get_Line will return the following -- line in the file. By default the registered callbacks are not called by -- Get_Line, this can activated by setting Callbacks (see Callback_Mode -- description above). File_Error may be raised if a file associated with -- Session is not readable. -- -- When Callbacks is not None, it is possible to exhaust all the lines -- of all the files associated with Session. In this case, File_Error -- is not raised. -- -- This procedure can be used from a subprogram called by procedure Parse -- or by an instantiation of For_Every_Line (see below). function End_Of_Data (Session : Session_Type := Current_Session) return Boolean; pragma Inline (End_Of_Data); -- Returns True if there is no more data to be processed in Session. It -- means that the latest session's file is being processed and that -- there is no more data to be read in this file (End_Of_File is True). function End_Of_File (Session : Session_Type := Current_Session) return Boolean; pragma Inline (End_Of_File); -- Returns True when there is no more data to be processed on the current -- session's file. procedure Close (Session : Session_Type); -- Release all associated data with Session. All memory allocated will -- be freed, the current file will be closed if needed, the callbacks -- will be unregistered. Close is convenient in reestablishing a session -- for new use. Get_Line is no longer usable (will raise File_Error) -- except after a successful call to Open, Parse or an instantiation -- of For_Every_Line. ----------------------------- -- For_Every_Line iterator -- ----------------------------- generic with procedure Action (Quit : in out Boolean); procedure For_Every_Line (Separators : String := Use_Current; Filename : String := Use_Current; Callbacks : Callback_Mode := None; Session : Session_Type := Current_Session); -- This is another iterator. Action will be called for each new -- record. The iterator's termination can be controlled by setting Quit -- to True. It is by default set to False. It is possible to specify a -- filename and a set of separators directly. This offer a quick way to -- parse a single file. These parameters will override those specified by -- Set_FS and Add_File. By default the registered callbacks are not called -- by For_Every_Line, this can activated by setting Callbacks (see -- Callback_Mode description above). The Session will be opened and -- closed automatically. File_Error is raised if there is no file -- associated with Session. It raises Session_Error is Session is already -- open. private type Session_Data; type Session_Data_Access is access Session_Data; type Session_Type is new Ada.Finalization.Limited_Controlled with record Data : Session_Data_Access; end record; procedure Initialize (Session : in out Session_Type); procedure Finalize (Session : in out Session_Type); end GNAT.AWK;