distrib/utils/more/decode.c

   1 /*      $NetBSD: decode.c,v 1.4 2003/08/07 09:27:59 agc Exp $   */
   2
   3 /*
   4  * Copyright (c) 1988 Mark Nudelman
   5  * Copyright (c) 1988, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <sys/cdefs.h>
  34 #ifndef lint
  35 #if 0
  36 static char sccsid[] = "@(#)decode.c    8.1 (Berkeley) 6/6/93";
  37 #else
  38 __RCSID("$NetBSD: decode.c,v 1.4 2003/08/07 09:27:59 agc Exp $");
  39 #endif
  40 #endif /* not lint */
  41
  42 /*
  43  * Routines to decode user commands.
  44  *
  45  * This is all table driven.
  46  * A command table is a sequence of command descriptors.
  47  * Each command descriptor is a sequence of bytes with the following format:
  48  *      <c1><c2>...<cN><0><action>
  49  * The characters c1,c2,...,cN are the command string; that is,
  50  * the characters which the user must type.
  51  * It is terminated by a null <0> byte.
  52  * The byte after the null byte is the action code associated
  53  * with the command string.
  54  *
  55  * The default commands are described by cmdtable.
  56  */
  57
  58 #include <sys/param.h>
  59 #include <sys/file.h>
  60 #include <stdio.h>
  61
  62 #include "less.h"
  63 #include "extern.h"
  64
  65 /*
  66  * Command table is ordered roughly according to expected
  67  * frequency of use, so the common commands are near the beginning.
  68  */
  69 #define CONTROL(c)              ((c)&037)
  70
  71 static char cmdtable[] = {
  72         '\r',0,                         A_F_LINE,
  73         '\n',0,                         A_F_LINE,
  74         'j',0,                          A_F_LINE,
  75         'k',0,                          A_B_LINE,
  76         'd',0,                          A_F_SCROLL,
  77         CONTROL('D'),0,                 A_F_SCROLL,
  78         'u',0,                          A_B_SCROLL,
  79         CONTROL('U'),0,                 A_B_SCROLL,
  80         ' ',0,                          A_F_SCREEN,
  81         'f',0,                          A_F_SCREEN,
  82         CONTROL('F'),0,                 A_F_SCREEN,
  83         'b',0,                          A_B_SCREEN,
  84         CONTROL('B'),0,                 A_B_SCREEN,
  85         'R',0,                          A_FREPAINT,
  86         'r',0,                          A_REPAINT,
  87         CONTROL('L'),0,                 A_REPAINT,
  88         'g',0,                          A_GOLINE,
  89         'p',0,                          A_PERCENT,
  90         '%',0,                          A_PERCENT,
  91         'G',0,                          A_GOEND,
  92         '0',0,                          A_DIGIT,
  93         '1',0,                          A_DIGIT,
  94         '2',0,                          A_DIGIT,
  95         '3',0,                          A_DIGIT,
  96         '4',0,                          A_DIGIT,
  97         '5',0,                          A_DIGIT,
  98         '6',0,                          A_DIGIT,
  99         '7',0,                          A_DIGIT,
 100         '8',0,                          A_DIGIT,
 101         '9',0,                          A_DIGIT,
 102
 103         '=',0,                          A_STAT,
 104         CONTROL('G'),0,                 A_STAT,
 105         '/',0,                          A_F_SEARCH,
 106         '?',0,                          A_B_SEARCH,
 107         'n',0,                          A_AGAIN_SEARCH,
 108         'm',0,                          A_SETMARK,
 109         '\'',0,                         A_GOMARK,
 110         'E',0,                          A_EXAMINE,
 111         'N',0,                          A_NEXT_FILE,
 112         ':','n',0,                      A_NEXT_FILE,
 113         'P',0,                          A_PREV_FILE,
 114         ':','p',0,                      A_PREV_FILE,
 115         'v',0,                          A_VISUAL,
 116
 117         'h',0,                          A_HELP,
 118         'q',0,                          A_QUIT,
 119         ':','q',0,                      A_QUIT,
 120         ':','t',0,                      A_TAGFILE,
 121         ':', 'a', 0,                    A_FILE_LIST,
 122         'Z','Z',0,                      A_QUIT,
 123 };
 124
 125 char *cmdendtable = cmdtable + sizeof(cmdtable);
 126
 127 #define MAX_CMDLEN      16
 128
 129 static char kbuf[MAX_CMDLEN+1];
 130 static char *kp = kbuf;
 131
 132 /*
 133  * Indicate that we're not in a prefix command
 134  * by resetting the command buffer pointer.
 135  */
 136 void
 137 noprefix()
 138 {
 139         kp = kbuf;
 140 }
 141
 142 /*
 143  * Decode a command character and return the associated action.
 144  */
 145 int
 146 cmd_decode(c)
 147         int c;
 148 {
 149         int action = A_INVALID;
 150
 151         /*
 152          * Append the new command character to the command string in kbuf.
 153          */
 154         *kp++ = c;
 155         *kp = '\0';
 156
 157         action = cmd_search(cmdtable, cmdendtable);
 158
 159         /* This is not a prefix character. */
 160         if (action != A_PREFIX)
 161                 noprefix();
 162         return(action);
 163 }
 164
 165 /*
 166  * Search a command table for the current command string (in kbuf).
 167  */
 168 int
 169 cmd_search(table, endtable)
 170         char *table;
 171         char *endtable;
 172 {
 173         char *p, *q;
 174
 175         for (p = table, q = kbuf;  p < endtable;  p++, q++) {
 176                 if (*p == *q) {
 177                         /*
 178                          * Current characters match.
 179                          * If we're at the end of the string, we've found it.
 180                          * Return the action code, which is the character
 181                          * after the null at the end of the string
 182                          * in the command table.
 183                          */
 184                         if (*p == '\0')
 185                                 return(p[1]);
 186                 }
 187                 else if (*q == '\0') {
 188                         /*
 189                          * Hit the end of the user's command,
 190                          * but not the end of the string in the command table.
 191                          * The user's command is incomplete.
 192                          */
 193                         return(A_PREFIX);
 194                 } else {
 195                         /*
 196                          * Not a match.
 197                          * Skip ahead to the next command in the
 198                          * command table, and reset the pointer
 199                          * to the user's command.
 200                          */
 201                         while (*p++ != '\0');
 202                         q = kbuf-1;
 203                 }
 204         }
 205         /*
 206          * No match found in the entire command table.
 207          */
 208         return(A_INVALID);
 209 }