intl/plural.y

   1 %{
   2 /* Expression parsing for plural form selection.
   3    Copyright (C) 2000-2022 Free Software Foundation, Inc.
   4    Written by Ulrich Drepper <drepper@cygnus.com>, 2000.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU Lesser General Public License as published by
   8    the Free Software Foundation; either version 2.1 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 /* For bison < 2.0, the bison generated parser uses alloca.  AIX 3 forces us
  20    to put this declaration at the beginning of the file.  The declaration in
  21    bison's skeleton file comes too late.  This must come before <config.h>
  22    because <config.h> may include arbitrary system headers.
  23    This can go away once the AM_INTL_SUBDIR macro requires bison >= 2.0.  */
  24 #if defined _AIX && !defined __GNUC__
  25  #pragma alloca
  26 #endif
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include <config.h>
  30 #endif
  31
  32 #include <stddef.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include "plural-exp.h"
  36
  37 /* The main function generated by the parser is called __gettextparse,
  38    but we want it to be called PLURAL_PARSE.  */
  39 #ifndef _LIBC
  40 # define __gettextparse PLURAL_PARSE
  41 #endif
  42
  43 /* Later we provide those prototypes.  Without these macros, bison may
  44    generate its own prototypes with possible conflicts.  */
  45 #define YYLEX_IS_DECLARED
  46 #define YYERROR_IS_DECLARED
  47
  48 %}
  49 %parse-param {struct parse_args *arg}
  50 %lex-param {struct parse_args *arg}
  51 %define api.pure full
  52 %expect 7
  53
  54 %union {
  55   unsigned long int num;
  56   enum expression_operator op;
  57   struct expression *exp;
  58 }
  59
  60 %{
  61 /* Prototypes for local functions.  */
  62 static int yylex (YYSTYPE *lval, struct parse_args *arg);
  63 static void yyerror (struct parse_args *arg, const char *str);
  64
  65 /* Allocation of expressions.  */
  66
  67 static struct expression *
  68 new_exp (int nargs, enum expression_operator op,
  69          struct expression * const *args)
  70 {
  71   int i;
  72   struct expression *newp;
  73
  74   /* If any of the argument could not be malloc'ed, just return NULL.  */
  75   for (i = nargs - 1; i >= 0; i--)
  76     if (args[i] == NULL)
  77       goto fail;
  78
  79   /* Allocate a new expression.  */
  80   newp = (struct expression *) malloc (sizeof (*newp));
  81   if (newp != NULL)
  82     {
  83       newp->nargs = nargs;
  84       newp->operation = op;
  85       for (i = nargs - 1; i >= 0; i--)
  86         newp->val.args[i] = args[i];
  87       return newp;
  88     }
  89
  90  fail:
  91   for (i = nargs - 1; i >= 0; i--)
  92     FREE_EXPRESSION (args[i]);
  93
  94   return NULL;
  95 }
  96
  97 static inline struct expression *
  98 new_exp_0 (enum expression_operator op)
  99 {
 100   return new_exp (0, op, NULL);
 101 }
 102
 103 static inline struct expression *
 104 new_exp_1 (enum expression_operator op, struct expression *right)
 105 {
 106   struct expression *args[1];
 107
 108   args[0] = right;
 109   return new_exp (1, op, args);
 110 }
 111
 112 static struct expression *
 113 new_exp_2 (enum expression_operator op, struct expression *left,
 114            struct expression *right)
 115 {
 116   struct expression *args[2];
 117
 118   args[0] = left;
 119   args[1] = right;
 120   return new_exp (2, op, args);
 121 }
 122
 123 static inline struct expression *
 124 new_exp_3 (enum expression_operator op, struct expression *bexp,
 125            struct expression *tbranch, struct expression *fbranch)
 126 {
 127   struct expression *args[3];
 128
 129   args[0] = bexp;
 130   args[1] = tbranch;
 131   args[2] = fbranch;
 132   return new_exp (3, op, args);
 133 }
 134
 135 %}
 136
 137 /* This declares that all operators have the same associativity and the
 138    precedence order as in C.  See [Harbison, Steele: C, A Reference Manual].
 139    There is no unary minus and no bitwise operators.
 140    Operators with the same syntactic behaviour have been merged into a single
 141    token, to save space in the array generated by bison.  */
 142 %right '?'              /*   ?          */
 143 %left '|'               /*   ||         */
 144 %left '&'               /*   &&         */
 145 %left EQUOP2            /*   == !=      */
 146 %left CMPOP2            /*   < > <= >=  */
 147 %left ADDOP2            /*   + -        */
 148 %left MULOP2            /*   * / %      */
 149 %right '!'              /*   !          */
 150
 151 %token <op> EQUOP2 CMPOP2 ADDOP2 MULOP2
 152 %token <num> NUMBER
 153 %type <exp> exp
 154
 155 %%
 156
 157 start:    exp
 158           {
 159             if ($1 == NULL)
 160               YYABORT;
 161             arg->res = $1;
 162           }
 163         ;
 164
 165 exp:      exp '?' exp ':' exp
 166           {
 167             $$ = new_exp_3 (qmop, $1, $3, $5);
 168           }
 169         | exp '|' exp
 170           {
 171             $$ = new_exp_2 (lor, $1, $3);
 172           }
 173         | exp '&' exp
 174           {
 175             $$ = new_exp_2 (land, $1, $3);
 176           }
 177         | exp EQUOP2 exp
 178           {
 179             $$ = new_exp_2 ($2, $1, $3);
 180           }
 181         | exp CMPOP2 exp
 182           {
 183             $$ = new_exp_2 ($2, $1, $3);
 184           }
 185         | exp ADDOP2 exp
 186           {
 187             $$ = new_exp_2 ($2, $1, $3);
 188           }
 189         | exp MULOP2 exp
 190           {
 191             $$ = new_exp_2 ($2, $1, $3);
 192           }
 193         | '!' exp
 194           {
 195             $$ = new_exp_1 (lnot, $2);
 196           }
 197         | 'n'
 198           {
 199             $$ = new_exp_0 (var);
 200           }
 201         | NUMBER
 202           {
 203             if (($$ = new_exp_0 (num)) != NULL)
 204               $$->val.num = $1;
 205           }
 206         | '(' exp ')'
 207           {
 208             $$ = $2;
 209           }
 210         ;
 211
 212 %%
 213
 214 void
 215 FREE_EXPRESSION (struct expression *exp)
 216 {
 217   if (exp == NULL)
 218     return;
 219
 220   /* Handle the recursive case.  */
 221   switch (exp->nargs)
 222     {
 223     case 3:
 224       FREE_EXPRESSION (exp->val.args[2]);
 225       /* FALLTHROUGH */
 226     case 2:
 227       FREE_EXPRESSION (exp->val.args[1]);
 228       /* FALLTHROUGH */
 229     case 1:
 230       FREE_EXPRESSION (exp->val.args[0]);
 231       /* FALLTHROUGH */
 232     default:
 233       break;
 234     }
 235
 236   free (exp);
 237 }
 238
 239
 240 static int
 241 yylex (YYSTYPE *lval, struct parse_args *arg)
 242 {
 243   const char *exp = arg->cp;
 244   int result;
 245
 246   while (1)
 247     {
 248       if (exp[0] == '\0')
 249         {
 250           arg->cp = exp;
 251           return YYEOF;
 252         }
 253
 254       if (exp[0] != ' ' && exp[0] != '\t')
 255         break;
 256
 257       ++exp;
 258     }
 259
 260   result = *exp++;
 261   switch (result)
 262     {
 263     case '0': case '1': case '2': case '3': case '4':
 264     case '5': case '6': case '7': case '8': case '9':
 265       {
 266         unsigned long int n = result - '0';
 267         while (exp[0] >= '0' && exp[0] <= '9')
 268           {
 269             n *= 10;
 270             n += exp[0] - '0';
 271             ++exp;
 272           }
 273         lval->num = n;
 274         result = NUMBER;
 275       }
 276       break;
 277
 278     case '=':
 279       if (exp[0] == '=')
 280         {
 281           ++exp;
 282           lval->op = equal;
 283           result = EQUOP2;
 284         }
 285       else
 286         result = YYERRCODE;
 287       break;
 288
 289     case '!':
 290       if (exp[0] == '=')
 291         {
 292           ++exp;
 293           lval->op = not_equal;
 294           result = EQUOP2;
 295         }
 296       break;
 297
 298     case '&':
 299     case '|':
 300       if (exp[0] == result)
 301         ++exp;
 302       else
 303         result = YYERRCODE;
 304       break;
 305
 306     case '<':
 307       if (exp[0] == '=')
 308         {
 309           ++exp;
 310           lval->op = less_or_equal;
 311         }
 312       else
 313         lval->op = less_than;
 314       result = CMPOP2;
 315       break;
 316
 317     case '>':
 318       if (exp[0] == '=')
 319         {
 320           ++exp;
 321           lval->op = greater_or_equal;
 322         }
 323       else
 324         lval->op = greater_than;
 325       result = CMPOP2;
 326       break;
 327
 328     case '*':
 329       lval->op = mult;
 330       result = MULOP2;
 331       break;
 332
 333     case '/':
 334       lval->op = divide;
 335       result = MULOP2;
 336       break;
 337
 338     case '%':
 339       lval->op = module;
 340       result = MULOP2;
 341       break;
 342
 343     case '+':
 344       lval->op = plus;
 345       result = ADDOP2;
 346       break;
 347
 348     case '-':
 349       lval->op = minus;
 350       result = ADDOP2;
 351       break;
 352
 353     case 'n':
 354     case '?':
 355     case ':':
 356     case '(':
 357     case ')':
 358       /* Nothing, just return the character.  */
 359       break;
 360
 361     case ';':
 362     case '\n':
 363     case '\0':
 364       /* Be safe and let the user call this function again.  */
 365       --exp;
 366       result = YYEOF;
 367       break;
 368
 369     default:
 370       result = YYERRCODE;
 371 #if YYDEBUG != 0
 372       --exp;
 373 #endif
 374       break;
 375     }
 376
 377   arg->cp = exp;
 378
 379   return result;
 380 }
 381
 382
 383 static void
 384 yyerror (struct parse_args *arg, const char *str)
 385 {
 386   /* Do nothing.  We don't print error messages here.  */
 387 }