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

   1 /* -*-c-*-
   2  *
   3  * $Id: lexer.l,v 1.4 1999/05/04 16:17:26 mdw Exp $
   4  *
   5  * Lexical analyser for `become.conf' files
   6  *
   7  * (c) 1998 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 1.4  1999/05/04 16:17:26  mdw
  33  * Change to header file name for parser.  See log for `parse.h' for
  34  * details.
  35  *
  36  * Revision 1.3  1998/01/12  16:46:07  mdw
  37  * Fix copyright date.
  38  *
  39  * Revision 1.2  1997/08/04 10:24:23  mdw
  40  * Sources placed under CVS control.
  41  *
  42  * Revision 1.1  1997/07/21  13:47:48  mdw
  43  * Initial revision
  44  *
  45  */
  46
  47 /*----- Declarations section ----------------------------------------------*/
  48
  49 /* --- Header files --- */
  50
  51 %{
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55
  56 #include "become.h"
  57 #include "lexer.h"
  58 #include "parse.h"
  59 #include "utils.h"
  60 %}
  61
  62 /* --- Start conditions --- */
  63
  64 %x s_KEYWORD
  65 %x s_NORMAL
  66 %x s_STRING
  67
  68 /* --- A handy static buffer --- */
  69
  70  static char lex__buff[4096];
  71  static char *lex__ptr;
  72
  73 /* --- Line number --- */
  74
  75  int lex_line;
  76
  77 %%
  78
  79  /*---- Main scanner definition -------------------------------------------*/
  80
  81  /* --- Comments --- */
  82
  83 <INITIAL,s_KEYWORD,s_NORMAL>{
  84   "#".*\n                       lex_line++;
  85
  86  /* --- Whitespace --- */
  87
  88   [ \t]                         /* munch */
  89   \n                            lex_line++;
  90 }
  91
  92  /* --- Keywords --- */
  93
  94 <INITIAL,s_KEYWORD>{
  95   user                          BEGIN(s_NORMAL); return (USER);
  96   command                       BEGIN(s_NORMAL); return (COMMAND);
  97   host                          BEGIN(s_NORMAL); return (HOST);
  98   allow                         BEGIN(s_NORMAL); return (ALLOW);
  99   port                          BEGIN(s_NORMAL); return (PORT);
 100   keyfile                       BEGIN(s_NORMAL); return (KEYFILE);
 101   .                             BEGIN(s_NORMAL); return (BADTOKEN);
 102 }
 103  /* --- Other sorts of tokens --- */
 104
 105 <s_NORMAL>{
 106   [0-9]*                        yylval.i = atoi(yytext); return (INT);
 107   [a-zA-Z_][a-zA-Z_0-9]*        yylval.s = yytext; return (WORD);
 108   \"                            BEGIN(s_STRING); lex__ptr = lex__buff;
 109   ";"                           BEGIN(s_KEYWORD); return (';');
 110   "->"                          return (ARROW);
 111   .                             return (yytext[0]);
 112 }
 113
 114  /* --- Strings and things --- *
 115   *
 116   * Be a little careful about buffer overflows here.
 117   */
 118
 119 <s_STRING>{
 120   \\.                           {
 121                                   if (lex__ptr >
 122                                       lex__buff + sizeof(lex__buff) - 8) {
 123                                     moan("string too long at line %i",
 124                                          lex_line);
 125                                     *lex__ptr++ = 0;
 126                                     yylval.s = lex__buff;
 127                                     BEGIN(s_NORMAL);
 128                                     return (STRING);
 129                                   }
 130                                   *lex__ptr++ = yytext[1];
 131                                 }
 132   \"                            {
 133                                   *lex__ptr++ = 0;
 134                                   yylval.s = lex__buff;
 135                                   BEGIN(s_NORMAL);
 136                                   return (STRING);
 137                                 }
 138   \n                            |
 139   <<EOF>>                       {
 140                                   moan("missing `\"', inserted at line %i",
 141                                        lex_line);
 142                                   lex_line++;
 143                                   *lex__ptr++ = 0;
 144                                   yylval.s = lex__buff;
 145                                   BEGIN(s_NORMAL);
 146                                   return (STRING);
 147                                 }
 148   .                             {
 149                                   if (lex__ptr >
 150                                       lex__buff + sizeof(lex__buff) - 8) {
 151                                     moan("string too long at line %i",
 152                                          lex_line);
 153                                     *lex__ptr++ = 0;
 154                                     yylval.s = lex__buff;
 155                                     BEGIN(s_NORMAL);
 156                                     return (STRING);
 157                                   }
 158                                   *lex__ptr++ = yytext[0];
 159                                 }
 160 }
 161
 162 %%
 163
 164 /*----- Support routines --------------------------------------------------*/
 165
 166 /* --- @lexer_scan@ --- *
 167  *
 168  * Arguments:   @FILE *fp@ = pointer to a stream object to scan
 169  *
 170  * Returns:     ---
 171  *
 172  * Use:         Initialises the scanner ready to parse from the given
 173  *              stream.
 174  */
 175
 176 void lexer_scan(FILE *fp)
 177 {
 178   yyin = fp;
 179   lex_line = 1;
 180   BEGIN(INITIAL);
 181 }
 182
 183 /*----- That's all, folks -------------------------------------------------*/