/* * Copyright (c) 1993-1994 by Xerox Corporation. All rights reserved. * * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. * * Permission is hereby granted to use or copy this program * for any purpose, provided the above notices are retained on all copies. * Permission to modify the code and to distribute modified code is granted, * provided the above notices are retained, and a notice that the code was * modified is included with the above copyright notice. * * Author: Hans-J. Boehm (boehm@parc.xerox.com) */ /* Boehm, October 5, 1995 4:20 pm PDT */ /* * Cords are immutable character strings. A number of operations * on long cords are much more efficient than their strings.h counterpart. * In particular, concatenation takes constant time independent of the length * of the arguments. (Cords are represented as trees, with internal * nodes representing concatenation and leaves consisting of either C * strings or a functional description of the string.) * * The following are reasonable applications of cords. They would perform * unacceptably if C strings were used: * - A compiler that produces assembly language output by repeatedly * concatenating instructions onto a cord representing the output file. * - A text editor that converts the input file to a cord, and then * performs editing operations by producing a new cord representing * the file after echa character change (and keeping the old ones in an * edit history) * * For optimal performance, cords should be built by * concatenating short sections. * This interface is designed for maximum compatibility with C strings. * ASCII NUL characters may be embedded in cords using CORD_from_fn. * This is handled correctly, but CORD_to_char_star will produce a string * with embedded NULs when given such a cord. * * This interface is fairly big, largely for performance reasons. * The most basic constants and functions: * * CORD - the type of a cord; * CORD_EMPTY - empty cord; * CORD_len(cord) - length of a cord; * CORD_cat(cord1,cord2) - concatenation of two cords; * CORD_substr(cord, start, len) - substring (or subcord); * CORD_pos i; CORD_FOR(i, cord) { ... CORD_pos_fetch(i) ... } - * examine each character in a cord. CORD_pos_fetch(i) is the char. * CORD_fetch(int i) - Retrieve i'th character (slowly). * CORD_cmp(cord1, cord2) - compare two cords. * CORD_from_file(FILE * f) - turn a read-only file into a cord. * CORD_to_char_star(cord) - convert to C string. * (Non-NULL C constant strings are cords.) * CORD_printf (etc.) - cord version of printf. Use %r for cords. */ # ifndef CORD_H # define CORD_H # include <stddef.h> # include <stdio.h> /* Cords have type const char *. This is cheating quite a bit, and not */ /* 100% portable. But it means that nonempty character string */ /* constants may be used as cords directly, provided the string is */ /* never modified in place. The empty cord is represented by, and */ /* can be written as, 0. */ typedef const char * CORD; /* An empty cord is always represented as nil */ # define CORD_EMPTY 0 /* Is a nonempty cord represented as a C string? */ #define CORD_IS_STRING(s) (*(s) != '\0') /* Concatenate two cords. If the arguments are C strings, they may */ /* not be subsequently altered. */ CORD CORD_cat(CORD x, CORD y); /* Concatenate a cord and a C string with known length. Except for the */ /* empty string case, this is a special case of CORD_cat. Since the */ /* length is known, it can be faster. */ /* The string y is shared with the resulting CORD. Hence it should */ /* not be altered by the caller. */ CORD CORD_cat_char_star(CORD x, const char * y, size_t leny); /* Compute the length of a cord */ size_t CORD_len(CORD x); /* Cords may be represented by functions defining the ith character */ typedef char (* CORD_fn)(size_t i, void * client_data); /* Turn a functional description into a cord. */ CORD CORD_from_fn(CORD_fn fn, void * client_data, size_t len); /* Return the substring (subcord really) of x with length at most n, */ /* starting at position i. (The initial character has position 0.) */ CORD CORD_substr(CORD x, size_t i, size_t n); /* Return the argument, but rebalanced to allow more efficient */ /* character retrieval, substring operations, and comparisons. */ /* This is useful only for cords that were built using repeated */ /* concatenation. Guarantees log time access to the result, unless */ /* x was obtained through a large number of repeated substring ops */ /* or the embedded functional descriptions take longer to evaluate. */ /* May reallocate significant parts of the cord. The argument is not */ /* modified; only the result is balanced. */ CORD CORD_balance(CORD x); /* The following traverse a cord by applying a function to each */ /* character. This is occasionally appropriate, especially where */ /* speed is crucial. But, since C doesn't have nested functions, */ /* clients of this sort of traversal are clumsy to write. Consider */ /* the functions that operate on cord positions instead. */ /* Function to iteratively apply to individual characters in cord. */ typedef int (* CORD_iter_fn)(char c, void * client_data); /* Function to apply to substrings of a cord. Each substring is a */ /* a C character string, not a general cord. */ typedef int (* CORD_batched_iter_fn)(const char * s, void * client_data); # define CORD_NO_FN ((CORD_batched_iter_fn)0) /* Apply f1 to each character in the cord, in ascending order, */ /* starting at position i. If */ /* f2 is not CORD_NO_FN, then multiple calls to f1 may be replaced by */ /* a single call to f2. The parameter f2 is provided only to allow */ /* some optimization by the client. This terminates when the right */ /* end of this string is reached, or when f1 or f2 return != 0. In the */ /* latter case CORD_iter returns != 0. Otherwise it returns 0. */ /* The specified value of i must be < CORD_len(x). */ int CORD_iter5(CORD x, size_t i, CORD_iter_fn f1, CORD_batched_iter_fn f2, void * client_data); /* A simpler version that starts at 0, and without f2: */ int CORD_iter(CORD x, CORD_iter_fn f1, void * client_data); # define CORD_iter(x, f1, cd) CORD_iter5(x, 0, f1, CORD_NO_FN, cd) /* Similar to CORD_iter5, but end-to-beginning. No provisions for */ /* CORD_batched_iter_fn. */ int CORD_riter4(CORD x, size_t i, CORD_iter_fn f1, void * client_data); /* A simpler version that starts at the end: */ int CORD_riter(CORD x, CORD_iter_fn f1, void * client_data); /* Functions that operate on cord positions. The easy way to traverse */ /* cords. A cord position is logically a pair consisting of a cord */ /* and an index into that cord. But it is much faster to retrieve a */ /* charcter based on a position than on an index. Unfortunately, */ /* positions are big (order of a few 100 bytes), so allocate them with */ /* caution. */ /* Things in cord_pos.h should be treated as opaque, except as */ /* described below. Also note that */ /* CORD_pos_fetch, CORD_next and CORD_prev have both macro and function */ /* definitions. The former may evaluate their argument more than once. */ # include "private/cord_pos.h" /* Visible definitions from above: typedef <OPAQUE but fairly big> CORD_pos[1]; * Extract the cord from a position: CORD CORD_pos_to_cord(CORD_pos p); * Extract the current index from a position: size_t CORD_pos_to_index(CORD_pos p); * Fetch the character located at the given position: char CORD_pos_fetch(CORD_pos p); * Initialize the position to refer to the given cord and index. * Note that this is the most expensive function on positions: void CORD_set_pos(CORD_pos p, CORD x, size_t i); * Advance the position to the next character. * P must be initialized and valid. * Invalidates p if past end: void CORD_next(CORD_pos p); * Move the position to the preceding character. * P must be initialized and valid. * Invalidates p if past beginning: void CORD_prev(CORD_pos p); * Is the position valid, i.e. inside the cord? int CORD_pos_valid(CORD_pos p); */ # define CORD_FOR(pos, cord) \ for (CORD_set_pos(pos, cord, 0); CORD_pos_valid(pos); CORD_next(pos)) /* An out of memory handler to call. May be supplied by client. */ /* Must not return. */ extern void (* CORD_oom_fn)(void); /* Dump the representation of x to stdout in an implementation defined */ /* manner. Intended for debugging only. */ void CORD_dump(CORD x); /* The following could easily be implemented by the client. They are */ /* provided in cordxtra.c for convenience. */ /* Concatenate a character to the end of a cord. */ CORD CORD_cat_char(CORD x, char c); /* Concatenate n cords. */ CORD CORD_catn(int n, /* CORD */ ...); /* Return the character in CORD_substr(x, i, 1) */ char CORD_fetch(CORD x, size_t i); /* Return < 0, 0, or > 0, depending on whether x < y, x = y, x > y */ int CORD_cmp(CORD x, CORD y); /* A generalization that takes both starting positions for the */ /* comparison, and a limit on the number of characters to be compared. */ int CORD_ncmp(CORD x, size_t x_start, CORD y, size_t y_start, size_t len); /* Find the first occurrence of s in x at position start or later. */ /* Return the position of the first character of s in x, or */ /* CORD_NOT_FOUND if there is none. */ size_t CORD_str(CORD x, size_t start, CORD s); /* Return a cord consisting of i copies of (possibly NUL) c. Dangerous */ /* in conjunction with CORD_to_char_star. */ /* The resulting representation takes constant space, independent of i. */ CORD CORD_chars(char c, size_t i); # define CORD_nul(i) CORD_chars('\0', (i)) /* Turn a file into cord. The file must be seekable. Its contents */ /* must remain constant. The file may be accessed as an immediate */ /* result of this call and/or as a result of subsequent accesses to */ /* the cord. Short files are likely to be immediately read, but */ /* long files are likely to be read on demand, possibly relying on */ /* stdio for buffering. */ /* We must have exclusive access to the descriptor f, i.e. we may */ /* read it at any time, and expect the file pointer to be */ /* where we left it. Normally this should be invoked as */ /* CORD_from_file(fopen(...)) */ /* CORD_from_file arranges to close the file descriptor when it is no */ /* longer needed (e.g. when the result becomes inaccessible). */ /* The file f must be such that ftell reflects the actual character */ /* position in the file, i.e. the number of characters that can be */ /* or were read with fread. On UNIX systems this is always true. On */ /* MS Windows systems, f must be opened in binary mode. */ CORD CORD_from_file(FILE * f); /* Equivalent to the above, except that the entire file will be read */ /* and the file pointer will be closed immediately. */ /* The binary mode restriction from above does not apply. */ CORD CORD_from_file_eager(FILE * f); /* Equivalent to the above, except that the file will be read on demand.*/ /* The binary mode restriction applies. */ CORD CORD_from_file_lazy(FILE * f); /* Turn a cord into a C string. The result shares no structure with */ /* x, and is thus modifiable. */ char * CORD_to_char_star(CORD x); /* Turn a C string into a CORD. The C string is copied, and so may */ /* subsequently be modified. */ CORD CORD_from_char_star(const char *s); /* Identical to the above, but the result may share structure with */ /* the argument and is thus not modifiable. */ const char * CORD_to_const_char_star(CORD x); /* Write a cord to a file, starting at the current position. No */ /* trailing NULs are newlines are added. */ /* Returns EOF if a write error occurs, 1 otherwise. */ int CORD_put(CORD x, FILE * f); /* "Not found" result for the following two functions. */ # define CORD_NOT_FOUND ((size_t)(-1)) /* A vague analog of strchr. Returns the position (an integer, not */ /* a pointer) of the first occurrence of (char) c inside x at position */ /* i or later. The value i must be < CORD_len(x). */ size_t CORD_chr(CORD x, size_t i, int c); /* A vague analog of strrchr. Returns index of the last occurrence */ /* of (char) c inside x at position i or earlier. The value i */ /* must be < CORD_len(x). */ size_t CORD_rchr(CORD x, size_t i, int c); /* The following are also not primitive, but are implemented in */ /* cordprnt.c. They provide functionality similar to the ANSI C */ /* functions with corresponding names, but with the following */ /* additions and changes: */ /* 1. A %r conversion specification specifies a CORD argument. Field */ /* width, precision, etc. have the same semantics as for %s. */ /* (Note that %c,%C, and %S were already taken.) */ /* 2. The format string is represented as a CORD. */ /* 3. CORD_sprintf and CORD_vsprintf assign the result through the 1st */ /* argument. Unlike their ANSI C versions, there is no need to guess */ /* the correct buffer size. */ /* 4. Most of the conversions are implement through the native */ /* vsprintf. Hence they are usually no faster, and */ /* idiosyncracies of the native printf are preserved. However, */ /* CORD arguments to CORD_sprintf and CORD_vsprintf are NOT copied; */ /* the result shares the original structure. This may make them */ /* very efficient in some unusual applications. */ /* The format string is copied. */ /* All functions return the number of characters generated or -1 on */ /* error. This complies with the ANSI standard, but is inconsistent */ /* with some older implementations of sprintf. */ /* The implementation of these is probably less portable than the rest */ /* of this package. */ #ifndef CORD_NO_IO #include <stdarg.h> int CORD_sprintf(CORD * out, CORD format, ...); int CORD_vsprintf(CORD * out, CORD format, va_list args); int CORD_fprintf(FILE * f, CORD format, ...); int CORD_vfprintf(FILE * f, CORD format, va_list args); int CORD_printf(CORD format, ...); int CORD_vprintf(CORD format, va_list args); #endif /* CORD_NO_IO */ # endif /* CORD_H */