chiark - git - mdw - become/blob - src/lexer.l

   1 /* -*-c-*-
   2  *
   3  * $Id: lexer.l,v 1.2 1997/08/04 10:24:23 mdw Exp $
   4  *
   5  * Lexical analyser for `become.conf' files
   6  *
   7  * (c) 1997 EBI
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of `become'
  13  *
  14  * `Become' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `Become' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `become'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: lexer.l,v $
  32  * Revision 1.2  1997/08/04 10:24:23  mdw
  33  * Sources placed under CVS control.
  34  *
  35  * Revision 1.1  1997/07/21  13:47:48  mdw
  36  * Initial revision
  37  *
  38  */
  39
  40 /*----- Declarations section ----------------------------------------------*/
  41
  42 /* --- Header files --- */
  43
  44 %{
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include "become.h"
  50 #include "lexer.h"
  51 #include "parser.h"
  52 #include "utils.h"
  53 %}
  54
  55 /* --- Start conditions --- */
  56
  57 %x s_KEYWORD
  58 %x s_NORMAL
  59 %x s_STRING
  60
  61 /* --- A handy static buffer --- */
  62
  63  static char lex__buff[4096];
  64  static char *lex__ptr;
  65
  66 /* --- Line number --- */
  67
  68  int lex_line;
  69
  70 %%
  71
  72  /*---- Main scanner definition -------------------------------------------*/
  73
  74  /* --- Comments --- */
  75
  76 <INITIAL,s_KEYWORD,s_NORMAL>{
  77   "#".*\n                       lex_line++;
  78
  79  /* --- Whitespace --- */
  80
  81   [ \t]                         /* munch */
  82   \n                            lex_line++;
  83 }
  84
  85  /* --- Keywords --- */
  86
  87 <INITIAL,s_KEYWORD>{
  88   user                          BEGIN(s_NORMAL); return (USER);
  89   command                       BEGIN(s_NORMAL); return (COMMAND);
  90   host                          BEGIN(s_NORMAL); return (HOST);
  91   allow                         BEGIN(s_NORMAL); return (ALLOW);
  92   port                          BEGIN(s_NORMAL); return (PORT);
  93   keyfile                       BEGIN(s_NORMAL); return (KEYFILE);
  94   .                             BEGIN(s_NORMAL); return (BADTOKEN);
  95 }
  96  /* --- Other sorts of tokens --- */
  97
  98 <s_NORMAL>{
  99   [0-9]*                        yylval.i = atoi(yytext); return (INT);
 100   [a-zA-Z_][a-zA-Z_0-9]*        yylval.s = yytext; return (WORD);
 101   \"                            BEGIN(s_STRING); lex__ptr = lex__buff;
 102   ";"                           BEGIN(s_KEYWORD); return (';');
 103   "->"                          return (ARROW);
 104   .                             return (yytext[0]);
 105 }
 106
 107  /* --- Strings and things --- *
 108   *
 109   * Be a little careful about buffer overflows here.
 110   */
 111
 112 <s_STRING>{
 113   \\.                           {
 114                                   if (lex__ptr >
 115                                       lex__buff + sizeof(lex__buff) - 8) {
 116                                     moan("string too long at line %i",
 117                                          lex_line);
 118                                     *lex__ptr++ = 0;
 119                                     yylval.s = lex__buff;
 120                                     BEGIN(s_NORMAL);
 121                                     return (STRING);
 122                                   }
 123                                   *lex__ptr++ = yytext[1];
 124                                 }
 125   \"                            {
 126                                   *lex__ptr++ = 0;
 127                                   yylval.s = lex__buff;
 128                                   BEGIN(s_NORMAL);
 129                                   return (STRING);
 130                                 }
 131   \n                            |
 132   <<EOF>>                       {
 133                                   moan("missing `\"', inserted at line %i",
 134                                        lex_line);
 135                                   lex_line++;
 136                                   *lex__ptr++ = 0;
 137                                   yylval.s = lex__buff;
 138                                   BEGIN(s_NORMAL);
 139                                   return (STRING);
 140                                 }
 141   .                             {
 142                                   if (lex__ptr >
 143                                       lex__buff + sizeof(lex__buff) - 8) {
 144                                     moan("string too long at line %i",
 145                                          lex_line);
 146                                     *lex__ptr++ = 0;
 147                                     yylval.s = lex__buff;
 148                                     BEGIN(s_NORMAL);
 149                                     return (STRING);
 150                                   }
 151                                   *lex__ptr++ = yytext[0];
 152                                 }
 153 }
 154
 155 %%
 156
 157 /*----- Support routines --------------------------------------------------*/
 158
 159 /* --- @lexer_scan@ --- *
 160  *
 161  * Arguments:   @FILE *fp@ = pointer to a stream object to scan
 162  *
 163  * Returns:     ---
 164  *
 165  * Use:         Initialises the scanner ready to parse from the given
 166  *              stream.
 167  */
 168
 169 void lexer_scan(FILE *fp)
 170 {
 171   yyin = fp;
 172   lex_line = 1;
 173   BEGIN(INITIAL);
 174 }
 175
 176 /*----- That's all, folks -------------------------------------------------*/