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