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Annotation of src/usr.bin/less/brac.c, Revision 1.1

1.1     ! etheisen    1: /*
        !             2:  * Copyright (c) 1984,1985,1989,1994,1995  Mark Nudelman
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice in the documentation and/or other materials provided with
        !            12:  *    the distribution.
        !            13:  *
        !            14:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
        !            15:  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            16:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
        !            17:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE
        !            18:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
        !            19:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
        !            20:  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
        !            21:  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
        !            22:  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
        !            23:  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
        !            24:  * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
        !            25:  */
        !            26:
        !            27:
        !            28: /*
        !            29:  * Routines to perform bracket matching functions.
        !            30:  */
        !            31:
        !            32: #include "less.h"
        !            33: #include "position.h"
        !            34:
        !            35: /*
        !            36:  * Try to match the n-th open bracket
        !            37:  *  which appears in the top displayed line (forwdir),
        !            38:  * or the n-th close bracket
        !            39:  *  which appears in the bottom displayed line (!forwdir).
        !            40:  * The characters which serve as "open bracket" and
        !            41:  * "close bracket" are given.
        !            42:  */
        !            43:        public void
        !            44: match_brac(obrac, cbrac, forwdir, n)
        !            45:        register int obrac;
        !            46:        register int cbrac;
        !            47:        int forwdir;
        !            48:        int n;
        !            49: {
        !            50:        register int c;
        !            51:        register int nest;
        !            52:        POSITION pos;
        !            53:        int (*chget)();
        !            54:
        !            55:        extern int ch_forw_get(), ch_back_get();
        !            56:
        !            57:        /*
        !            58:         * Seek to the line containing the open bracket.
        !            59:         * This is either the top or bottom line on the screen,
        !            60:         * depending on the type of bracket.
        !            61:         */
        !            62:        pos = position((forwdir) ? TOP : BOTTOM);
        !            63:        if (pos == NULL_POSITION || ch_seek(pos))
        !            64:        {
        !            65:                if (forwdir)
        !            66:                        error("Nothing in top line", NULL_PARG);
        !            67:                else
        !            68:                        error("Nothing in bottom line", NULL_PARG);
        !            69:                return;
        !            70:        }
        !            71:
        !            72:        /*
        !            73:         * Look thru the line to find the open bracket to match.
        !            74:         */
        !            75:        do
        !            76:        {
        !            77:                if ((c = ch_forw_get()) == '\n' || c == EOI)
        !            78:                {
        !            79:                        if (forwdir)
        !            80:                                error("No bracket in top line", NULL_PARG);
        !            81:                        else
        !            82:                                error("No bracket in bottom line", NULL_PARG);
        !            83:                        return;
        !            84:                }
        !            85:        } while (c != obrac || --n > 0);
        !            86:
        !            87:        /*
        !            88:         * Position the file just "after" the open bracket
        !            89:         * (in the direction in which we will be searching).
        !            90:         * If searching forward, we are already after the bracket.
        !            91:         * If searching backward, skip back over the open bracket.
        !            92:         */
        !            93:        if (!forwdir)
        !            94:                (void) ch_back_get();
        !            95:
        !            96:        /*
        !            97:         * Search the file for the matching bracket.
        !            98:         */
        !            99:        chget = (forwdir) ? ch_forw_get : ch_back_get;
        !           100:        nest = 0;
        !           101:        while ((c = (*chget)()) != EOI)
        !           102:        {
        !           103:                if (c == obrac)
        !           104:                        nest++;
        !           105:                else if (c == cbrac && --nest < 0)
        !           106:                {
        !           107:                        /*
        !           108:                         * Found the matching bracket.
        !           109:                         * If searching backward, put it on the top line.
        !           110:                         * If searching forward, put it on the bottom line.
        !           111:                         */
        !           112:                        jump_line_loc(ch_tell(), forwdir ? -1 : 1);
        !           113:                        return;
        !           114:                }
        !           115:        }
        !           116:        error("No matching bracket", NULL_PARG);
        !           117: }