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/*

 * 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 */