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Diffstat (limited to 'gc/include/cord.h')
| -rw-r--r-- | gc/include/cord.h | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/gc/include/cord.h b/gc/include/cord.h new file mode 100644 index 0000000..584112f --- /dev/null +++ b/gc/include/cord.h @@ -0,0 +1,327 @@ +/* + * 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 fo 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 */ |