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