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cord_pos.h
118 lines (96 loc) · 4 KB
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cord_pos.h
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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.
*/
/* Boehm, May 19, 1994 2:23 pm PDT */
# ifndef CORD_POSITION_H
/* The representation of CORD_position. This is private to the */
/* implementation, but the size is known to clients. Also */
/* the implementation of some exported macros relies on it. */
/* Don't use anything defined here and not in cord.h. */
# define MAX_DEPTH 48
/* The maximum depth of a balanced cord + 1. */
/* We don't let cords get deeper than MAX_DEPTH. */
struct CORD_pe {
CORD pe_cord;
size_t pe_start_pos;
};
/* A structure describing an entry on the path from the root */
/* to current position. */
typedef struct CORD_Pos {
size_t cur_pos;
int path_len;
# define CORD_POS_INVALID (0x55555555)
/* path_len == INVALID <==> position invalid */
const char *cur_leaf; /* Current leaf, if it is a string. */
/* If the current leaf is a function, */
/* then this may point to function_buf */
/* containing the next few characters. */
/* Always points to a valid string */
/* containing the current character */
/* unless cur_end is 0. */
size_t cur_start; /* Start position of cur_leaf */
size_t cur_end; /* Ending position of cur_leaf */
/* 0 if cur_leaf is invalid. */
struct CORD_pe path[MAX_DEPTH + 1];
/* path[path_len] is the leaf corresponding to cur_pos */
/* path[0].pe_cord is the cord we point to. */
# define FUNCTION_BUF_SZ 8
char function_buf[FUNCTION_BUF_SZ]; /* Space for next few chars */
/* from function node. */
} 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 give 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);
char CORD__pos_fetch(CORD_pos);
void CORD__next(CORD_pos);
void CORD__prev(CORD_pos);
#define CORD_pos_fetch(p) \
(((p)[0].cur_end != 0)? \
(p)[0].cur_leaf[(p)[0].cur_pos - (p)[0].cur_start] \
: CORD__pos_fetch(p))
#define CORD_next(p) \
(((p)[0].cur_pos + 1 < (p)[0].cur_end)? \
(p)[0].cur_pos++ \
: (CORD__next(p), 0))
#define CORD_prev(p) \
(((p)[0].cur_end != 0 && (p)[0].cur_pos > (p)[0].cur_start)? \
(p)[0].cur_pos-- \
: (CORD__prev(p), 0))
#define CORD_pos_to_index(p) ((p)[0].cur_pos)
#define CORD_pos_to_cord(p) ((p)[0].path[0].pe_cord)
#define CORD_pos_valid(p) ((p)[0].path_len != CORD_POS_INVALID)
/* Some grubby stuff for performance-critical friends: */
#define CORD_pos_chars_left(p) ((long)((p)[0].cur_end) - (long)((p)[0].cur_pos))
/* Number of characters in cache. <= 0 ==> none */
#define CORD_pos_advance(p,n) ((p)[0].cur_pos += (n) - 1, CORD_next(p))
/* Advance position by n characters */
/* 0 < n < CORD_pos_chars_left(p) */
#define CORD_pos_cur_char_addr(p) \
(p)[0].cur_leaf + ((p)[0].cur_pos - (p)[0].cur_start)
/* address of current character in cache. */
#endif