diplodocus.org Git - nmh/blob - docs/historical/mh-6.8.5/miscellany/less-177/decode.c

   1 /*
   2  * Routines to decode user commands.
   3  *
   4  * This is all table driven.
   5  * A command table is a sequence of command descriptors.
   6  * Each command descriptor is a sequence of bytes with the following format:
   7  *      <c1><c2>...<cN><0><action>
   8  * The characters c1,c2,...,cN are the command string; that is,
   9  * the characters which the user must type.
  10  * It is terminated by a null <0> byte.
  11  * The byte after the null byte is the action code associated
  12  * with the command string.
  13  * If an action byte is OR-ed with A_EXTRA, this indicates
  14  * that the option byte is followed by an extra string.
  15  *
  16  * There may be many command tables.
  17  * The first (default) table is built-in.
  18  * Other tables are read in from "lesskey" files.
  19  * All the tables are linked together and are searched in order.
  20  */
  21
  22 #include "less.h"
  23 #include "cmd.h"
  24 #if __MSDOS__
  25 #include <io.h>
  26 #include <stdlib.h>
  27 #endif
  28
  29 /*
  30  * Command table is ordered roughly according to expected
  31  * frequency of use, so the common commands are near the beginning.
  32  */
  33 static char cmdtable[] =
  34 {
  35 #if __MSDOS__
  36         /*
  37          * PC function keys.
  38          * Note that '\0' is converted to '\200' on input.
  39          */
  40         '\200','\120',0,                A_F_LINE,               /* down arrow */
  41         '\200','\121',0,                A_F_SCREEN,             /* page down */
  42         '\200','\110',0,                A_B_LINE,               /* up arrow */
  43         '\200','\111',0,                A_B_SCREEN,             /* page up */
  44         '\200','\107',0,                A_GOLINE,               /* home */
  45         '\200','\117',0,                A_GOEND,                /* end */
  46         '\200','\073',0,                A_HELP,                 /* F1 */
  47         '\200','\104',0,                A_MODIFY_WINDOW,        /* F10 */
  48         '\200','\103',0,                A_MODIFY_COLOURS,       /* F9 */
  49 #endif
  50         '\r',0,                         A_F_LINE,
  51         '\n',0,                         A_F_LINE,
  52         'e',0,                          A_F_LINE,
  53         'j',0,                          A_F_LINE,
  54         CONTROL('E'),0,                 A_F_LINE,
  55         CONTROL('N'),0,                 A_F_LINE,
  56         'k',0,                          A_B_LINE,
  57         'y',0,                          A_B_LINE,
  58         CONTROL('Y'),0,                 A_B_LINE,
  59         CONTROL('K'),0,                 A_B_LINE,
  60         CONTROL('P'),0,                 A_B_LINE,
  61         'J',0,                          A_FF_LINE,
  62         'K',0,                          A_BF_LINE,
  63         'Y',0,                          A_BF_LINE,
  64         'd',0,                          A_F_SCROLL,
  65         CONTROL('D'),0,                 A_F_SCROLL,
  66         'u',0,                          A_B_SCROLL,
  67         CONTROL('U'),0,                 A_B_SCROLL,
  68         ' ',0,                          A_F_SCREEN,
  69         'f',0,                          A_F_SCREEN,
  70         CONTROL('F'),0,                 A_F_SCREEN,
  71         CONTROL('V'),0,                 A_F_SCREEN,
  72         'b',0,                          A_B_SCREEN,
  73         CONTROL('B'),0,                 A_B_SCREEN,
  74         ESC,'v',0,                      A_B_SCREEN,
  75         'z',0,                          A_F_WINDOW,
  76         'w',0,                          A_B_WINDOW,
  77         'F',0,                          A_F_FOREVER,
  78         'R',0,                          A_FREPAINT,
  79         'r',0,                          A_REPAINT,
  80         CONTROL('R'),0,                 A_REPAINT,
  81         CONTROL('L'),0,                 A_REPAINT,
  82         'g',0,                          A_GOLINE,
  83         '<',0,                          A_GOLINE,
  84         ESC,'<',0,                      A_GOLINE,
  85         'p',0,                          A_PERCENT,
  86         '%',0,                          A_PERCENT,
  87         '{',0,                          A_F_BRACKET|A_EXTRA,    '{','}',0,
  88         '}',0,                          A_B_BRACKET|A_EXTRA,    '{','}',0,
  89         '(',0,                          A_F_BRACKET|A_EXTRA,    '(',')',0,
  90         ')',0,                          A_B_BRACKET|A_EXTRA,    '(',')',0,
  91         '[',0,                          A_F_BRACKET|A_EXTRA,    '[',']',0,
  92         ']',0,                          A_B_BRACKET|A_EXTRA,    '[',']',0,
  93         ESC,CONTROL('F'),0,             A_F_BRACKET,
  94         ESC,CONTROL('B'),0,             A_B_BRACKET,
  95         'G',0,                          A_GOEND,
  96         ESC,'>',0,                      A_GOEND,
  97         '>',0,                          A_GOEND,
  98         'P',0,                          A_GOPOS,
  99
 100         '0',0,                          A_DIGIT,
 101         '1',0,                          A_DIGIT,
 102         '2',0,                          A_DIGIT,
 103         '3',0,                          A_DIGIT,
 104         '4',0,                          A_DIGIT,
 105         '5',0,                          A_DIGIT,
 106         '6',0,                          A_DIGIT,
 107         '7',0,                          A_DIGIT,
 108         '8',0,                          A_DIGIT,
 109         '9',0,                          A_DIGIT,
 110
 111         '=',0,                          A_STAT,
 112         CONTROL('G'),0,                 A_STAT,
 113         ':','f',0,                      A_STAT,
 114         '/',0,                          A_F_SEARCH,
 115         '?',0,                          A_B_SEARCH,
 116         ESC,'/',0,                      A_F_SEARCH|A_EXTRA,     '*',0,
 117         ESC,'?',0,                      A_B_SEARCH|A_EXTRA,     '*',0,
 118         'n',0,                          A_AGAIN_SEARCH,
 119         ESC,'n',0,                      A_T_AGAIN_SEARCH,
 120         'N',0,                          A_REVERSE_SEARCH,
 121         ESC,'N',0,                      A_T_REVERSE_SEARCH,
 122         'm',0,                          A_SETMARK,
 123         '\'',0,                         A_GOMARK,
 124         CONTROL('X'),CONTROL('X'),0,    A_GOMARK,
 125         'E',0,                          A_EXAMINE,
 126         ':','e',0,                      A_EXAMINE,
 127         CONTROL('X'),CONTROL('V'),0,    A_EXAMINE,
 128         ':','n',0,                      A_NEXT_FILE,
 129         ':','p',0,                      A_PREV_FILE,
 130         ':','x',0,                      A_INDEX_FILE,
 131         '-',0,                          A_OPT_TOGGLE,
 132         ':','t',0,                      A_OPT_TOGGLE|A_EXTRA,   't',0,
 133         's',0,                          A_OPT_TOGGLE|A_EXTRA,   'o',0,
 134         '_',0,                          A_DISP_OPTION,
 135         '|',0,                          A_PIPE,
 136         'v',0,                          A_VISUAL,
 137         '!',0,                          A_SHELL,
 138         '+',0,                          A_FIRSTCMD,
 139
 140         'H',0,                          A_HELP,
 141         'h',0,                          A_HELP,
 142         'V',0,                          A_VERSION,
 143         'q',0,                          A_QUIT,
 144         ':','q',0,                      A_QUIT,
 145         ':','Q',0,                      A_QUIT,
 146         'Z','Z',0,                      A_QUIT,
 147         ESC,ESC,0,                      A_QUIT,
 148 };
 149
 150 /*
 151  * Structure to support a list of command tables.
 152  */
 153 struct tablelist
 154 {
 155         struct tablelist *t_next;
 156         char *t_start;
 157         char *t_end;
 158 };
 159
 160 /*
 161  * Structure for the default command table.
 162  */
 163 static struct tablelist deftable =
 164         { NULL, cmdtable, cmdtable+sizeof(cmdtable) };
 165
 166 /*
 167  * List of tables; initially contains only the default table.
 168  */
 169 static struct tablelist *tables = &deftable;
 170
 171 static int cmd_search();
 172
 173 extern int erase_char, kill_char;
 174
 175 /*
 176  * Decode a command character and return the associated action.
 177  * The "extra" string, if any, is returned in sp.
 178  */
 179         public int
 180 cmd_decode(cmd, sp)
 181         char *cmd;
 182         char **sp;
 183 {
 184         register struct tablelist *t;
 185         register int action;
 186
 187         /*
 188          * Search thru all the command tables.
 189          * Stop when we find an action which is not A_INVALID.
 190          */
 191         for (t = tables;  t != NULL;  t = t->t_next)
 192         {
 193                 action = cmd_search(cmd, t->t_start, t->t_end, sp);
 194                 if (action != A_INVALID)
 195                         break;
 196         }
 197         return (action);
 198 }
 199
 200 /*
 201  * Search a command table for the current command string (in cmd).
 202  */
 203         static int
 204 cmd_search(cmd, table, endtable, sp)
 205         char *cmd;
 206         char *table;
 207         char *endtable;
 208         char **sp;
 209 {
 210         register char *p;
 211         register char *q;
 212         register int a;
 213
 214         for (p = table, q = cmd;  p < endtable;  p++, q++)
 215         {
 216                 if (*p == *q)
 217                 {
 218                         /*
 219                          * Current characters match.
 220                          * If we're at the end of the string, we've found it.
 221                          * Return the action code, which is the character
 222                          * after the null at the end of the string
 223                          * in the command table.
 224                          */
 225                         if (*p == '\0')
 226                         {
 227                                 a = *++p & 0377;
 228                                 /*
 229                                  * Check for an "extra" string.
 230                                  */
 231                                 if (a & A_EXTRA)
 232                                 {
 233                                         *sp = ++p;
 234                                         a &= ~A_EXTRA;
 235                                 } else
 236                                         *sp = NULL;
 237                                 return (a);
 238                         }
 239                 } else if (*q == '\0')
 240                 {
 241                         /*
 242                          * Hit the end of the user's command,
 243                          * but not the end of the string in the command table.
 244                          * The user's command is incomplete.
 245                          */
 246                         return (A_PREFIX);
 247                 } else
 248                 {
 249                         /*
 250                          * Not a match.
 251                          * Skip ahead to the next command in the
 252                          * command table, and reset the pointer
 253                          * to the beginning of the user's command.
 254                          */
 255                         while (*p++ != '\0') ;
 256                         if (*p & A_EXTRA)
 257                                 while (*++p != '\0') ;
 258                         q = cmd-1;
 259                 }
 260         }
 261         /*
 262          * No match found in the entire command table.
 263          */
 264         return (A_INVALID);
 265 }
 266
 267 #if USERFILE
 268 /*
 269  * Set up a user command table, based on a "lesskey" file.
 270  */
 271         public int
 272 add_cmdtable(filename)
 273         char *filename;
 274 {
 275         register struct tablelist *t;
 276         register POSITION len;
 277         register long n;
 278         register int f;
 279
 280         /*
 281          * Try to open the lesskey file.
 282          * If we can't, return an error.
 283          */
 284         f = open(filename, 0);
 285         if (f < 0)
 286                 return (-1);
 287
 288         /*
 289          * Read the file into the user table.
 290          * We first figure out the size of the file and allocate space for it.
 291          * {{ Minimal error checking is done here.
 292          *    A garbage .less file will produce strange results.
 293          *    To avoid a large amount of error checking code here, we
 294          *    rely on the lesskey program to generate a good .less file. }}
 295          */
 296         len = filesize(f);
 297         if (len == NULL_POSITION || len < 3)
 298         {
 299                 /*
 300                  * Bad file (valid file must have at least 3 chars).
 301                  */
 302                 close(f);
 303                 return (-1);
 304         }
 305         if ((t = (struct tablelist *)
 306                         calloc(1, sizeof(struct tablelist))) == NULL)
 307         {
 308                 close(f);
 309                 return (-1);
 310         }
 311         if ((t->t_start = (char *) calloc(len, sizeof(char))) == NULL)
 312         {
 313                 free((char *)t);
 314                 close(f);
 315                 return (-1);
 316         }
 317         if (lseek(f, (offset_t)0, 0) == BAD_LSEEK)
 318         {
 319                 free(t->t_start);
 320                 free((char *)t);
 321                 close(f);
 322                 return (-1);
 323         }
 324         n = read(f, t->t_start, (unsigned int) len);
 325         close(f);
 326
 327         /*
 328          * In a valid lesskey file, the last byte or
 329          * the second to the last byte must be zero.
 330          */
 331         if (n != len || (t->t_start[n-1] != '\0' && t->t_start[n-2] != '\0'))
 332         {
 333                 free(t->t_start);
 334                 free((char *)t);
 335                 return (-1);
 336         }
 337         t->t_end = t->t_start + n;
 338
 339         /*
 340          * Link it into the list of tables.
 341          */
 342         t->t_next = tables;
 343         tables = t;
 344         return (0);
 345 }
 346
 347 /*
 348  * Try to add the lesskey file "$HOME/.less"
 349  */
 350         public void
 351 add_hometable()
 352 {
 353         char *filename;
 354
 355 #if __MSDOS__
 356         filename = homefile("_less");
 357 #else
 358         filename = homefile(".less");
 359 #endif
 360         if (filename == NULL)
 361                 return;
 362         /*
 363          * Ignore errors.
 364          */
 365         (void) add_cmdtable(filename);
 366         free(filename);
 367 }
 368 #endif