/*
 * Copyright (C) 1984-2012  Mark Nudelman
 * Modified for use with illumos by Garrett D'Amore.
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information, see the README file.
 */

/*
 * Routines to perform bracket matching functions.
 */

#include "less.h"
#include "position.h"

/*
 * Try to match the n-th open bracket
 *  which appears in the top displayed line (forwdir),
 * or the n-th close bracket
 *  which appears in the bottom displayed line (!forwdir).
 * The characters which serve as "open bracket" and
 * "close bracket" are given.
 */
void
match_brac(int obrac, int cbrac, int forwdir, int n)
{
        int c;
        int nest;
        off_t pos;
        int (*chget)(void);

        /*
         * Seek to the line containing the open bracket.
         * This is either the top or bottom line on the screen,
         * depending on the type of bracket.
         */
        pos = position((forwdir) ? TOP : BOTTOM);
        if (pos == -1 || ch_seek(pos)) {
                if (forwdir)
                        error("Nothing in top line", NULL);
                else
                        error("Nothing in bottom line", NULL);
                return;
        }

        /*
         * Look thru the line to find the open bracket to match.
         */
        do {
                if ((c = ch_forw_get()) == '\n' || c == EOI) {
                        if (forwdir)
                                error("No bracket in top line", NULL);
                        else
                                error("No bracket in bottom line", NULL);
                        return;
                }
        } while (c != obrac || --n > 0);

        /*
         * Position the file just "after" the open bracket
         * (in the direction in which we will be searching).
         * If searching forward, we are already after the bracket.
         * If searching backward, skip back over the open bracket.
         */
        if (!forwdir)
                (void) ch_back_get();

        /*
         * Search the file for the matching bracket.
         */
        chget = (forwdir) ? ch_forw_get : ch_back_get;
        nest = 0;
        while ((c = (*chget)()) != EOI) {
                if (c == obrac) {
                        if (nest == INT_MAX)
                                break;
                        nest++;
                } else if (c == cbrac && --nest < 0) {
                        /*
                         * Found the matching bracket.
                         * If searching backward, put it on the top line.
                         * If searching forward, put it on the bottom line.
                         */
                        jump_line_loc(ch_tell(), forwdir ? -1 : 1);
                        return;
                }
        }
        error("No matching bracket", NULL);
}