+/*
+ * 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)
+ */
+
+/*
+ * 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 each 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 */
+/* character 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 */
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