src/tables.h

   1 /* Prepare the LALR and GLR parser tables.
   2    Copyright (C) 2002, 2004, 2009 Free Software Foundation, Inc.
   3
   4    This file is part of Bison, the GNU Compiler Compiler.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation, either version 3 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 General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef TABLES_H_
  20 # define TABLES_H_
  21
  22 # include "state.h"
  23
  24 /* The parser tables consist of these tables.
  25
  26    YYTRANSLATE = vector mapping yylex's token numbers into bison's
  27    token numbers.
  28
  29    YYTNAME = vector of string-names indexed by bison token number.
  30
  31    YYTOKNUM = vector of yylex token numbers corresponding to entries
  32    in YYTNAME.
  33
  34    YYRLINE = vector of line-numbers of all rules.  For yydebug
  35    printouts.
  36
  37    YYRHS = vector of items of all rules.  This is exactly what RITEMS
  38    contains.  For yydebug and for semantic parser.
  39
  40    YYPRHS[R] = index in YYRHS of first item for rule R.
  41
  42    YYR1[R] = symbol number of symbol that rule R derives.
  43
  44    YYR2[R] = number of symbols composing right hand side of rule R.
  45
  46    YYSTOS[S] = the symbol number of the symbol that leads to state S.
  47
  48    YYDEFACT[S] = default reduction number in state s.  Performed when
  49    YYTABLE doesn't specify something else to do.  Zero means the default
  50    is an error.
  51
  52    YYDEFGOTO[I] = default state to go to after a reduction of a rule
  53    that generates variable NTOKENS + I, except when YYTABLE specifies
  54    something else to do.
  55
  56    YYPACT[S] = index in YYTABLE of the portion describing state S.
  57    The lookahead token's number, I, is used to index that portion of
  58    YYTABLE to find out what action to perform.
  59
  60    If YYPACT[S] == YYPACT_NINF, if YYPACT[S] + I is outside the bounds
  61    of YYTABLE (from 0 to YYLAST), or if YYCHECK indicates that I is
  62    outside the bounds of the portion for S, then the default action
  63    (from YYDEFACT and YYDEFGOTO) should be used instead of YYTABLE.
  64    Otherwise, the value YYTABLE[YYPACT[S] + I] should be used even if
  65    YYPACT[S] < 0.
  66
  67    If the value in YYTABLE is positive, we shift the token and go to
  68    that state.
  69
  70    If the value is negative, it is minus a rule number to reduce by.
  71
  72    If the value is zero, the default action from YYDEFACT[S] is used.
  73
  74    If the value is YYTABLE_NINF, it's a syntax error.
  75
  76    YYPGOTO[I] = the index in YYTABLE of the portion describing what to
  77    do after reducing a rule that derives variable I + NTOKENS.  This
  78    portion is indexed by the parser state number, S, as of before the
  79    text for this nonterminal was read.  The value from YYTABLE is the
  80    state to go to if the corresponding value in YYCHECK is S.
  81
  82    YYTABLE = a vector filled with portions for different uses, found
  83    via YYPACT and YYPGOTO.
  84
  85    YYCHECK = a vector indexed in parallel with YYTABLE.  It indicates,
  86    in a roundabout way, the bounds of the portion you are trying to
  87    examine.
  88
  89    Suppose that the portion of YYTABLE starts at index P and the index
  90    to be examined within the portion is I.  Then if YYCHECK[P+I] != I,
  91    I is outside the bounds of what is actually allocated, and the
  92    default (from YYDEFACT or YYDEFGOTO) should be used.  Otherwise,
  93    YYTABLE[P+I] should be used.
  94
  95    YYFINAL = the state number of the termination state.
  96
  97    YYLAST ( = high) the number of the last element of YYTABLE, i.e.,
  98    sizeof (YYTABLE) - 1.  */
  99
 100 extern int nvectors;
 101
 102 typedef int base_number;
 103 extern base_number *base;
 104 /* A distinguished value of BASE, negative infinite.  During the
 105    computation equals to BASE_MINIMUM, later mapped to BASE_NINF to
 106    keep parser tables small.  */
 107 extern base_number base_ninf;
 108
 109 extern unsigned int *conflict_table;
 110 extern unsigned int *conflict_list;
 111 extern int conflict_list_cnt;
 112
 113 extern base_number *table;
 114 extern base_number *check;
 115 /* The value used in TABLE to denote explicit syntax errors
 116    (%nonassoc), a negative infinite.  */
 117 extern base_number table_ninf;
 118
 119 extern state_number *yydefgoto;
 120 extern rule_number *yydefact;
 121 extern int high;
 122
 123 void tables_generate (void);
 124 void tables_free (void);
 125
 126 #endif /* !TABLES_H_ */