src/tables.h

   1 /* Prepare the LALR and GLR parser tables.
   2    Copyright (C) 2002, 2004, 2009-2010 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    YYFINAL = the state number of the termination state.
  49
  50    YYTABLE = a vector filled with portions for different uses, found
  51    via YYPACT and YYPGOTO, described below.
  52
  53    YYLAST ( = high) the number of the last element of YYTABLE, i.e.,
  54    sizeof (YYTABLE) - 1.
  55
  56    YYCHECK = a vector indexed in parallel with YYTABLE.  It indicates,
  57    in a roundabout way, the bounds of the portion you are trying to
  58    examine.
  59
  60    Suppose that the portion of YYTABLE starts at index P and the index
  61    to be examined within the portion is I.  Then if YYCHECK[P+I] != I,
  62    I is outside the bounds of what is actually allocated, and the
  63    default (from YYDEFACT or YYDEFGOTO) should be used.  Otherwise,
  64    YYTABLE[P+I] should be used.
  65
  66    YYDEFACT[S] = default reduction number in state s.  Performed when
  67    YYTABLE doesn't specify something else to do.  Zero means the default
  68    is an error.
  69
  70    YYDEFGOTO[I] = default state to go to after a reduction of a rule
  71    that generates variable NTOKENS + I, except when YYTABLE specifies
  72    something else to do.
  73
  74    YYPACT[S] = index in YYTABLE of the portion describing state S.
  75    The lookahead token's number, I, is used to index that portion of
  76    YYTABLE to find out what action to perform.
  77
  78    If YYPACT[S] == YYPACT_NINF, if YYPACT[S] + I is outside the bounds
  79    of YYTABLE (from 0 to YYLAST), or I is outside the bounds for portion
  80    S (that is, YYCHECK[YYPACT[S] + I] != I), then the default action
  81    (that is, YYDEFACT[S]) should be used instead of YYTABLE.  Otherwise,
  82    the value YYTABLE[YYPACT[S] + I] should be used even if
  83    YYPACT[S] < 0.
  84
  85    If the value in YYTABLE is positive, we shift the token and go to
  86    that state.
  87
  88    If the value is negative, it is minus a rule number to reduce by.
  89
  90    If the value is YYTABLE_NINF, it's a syntax error.
  91
  92    YYPGOTO[I] = the index in YYTABLE of the portion describing what to
  93    do after reducing a rule that derives variable I + NTOKENS.  This
  94    portion is indexed by the parser state number, S, as of before the
  95    text for this nonterminal was read.
  96
  97    If YYPGOTO[I] + S is outside the bounds of YYTABLE (from 0 to YYLAST)
  98    or if S is outside the bounds of the portion for I (that is,
  99    YYCHECK[YYPGOTO[I] + S] != S), then the default state (that is,
 100    YYDEFGOTO[I]) should be used instead of YYTABLE.  Otherwise,
 101    YYTABLE[YYPGOTO[I] + S] is the state to go to even if YYPGOTO[I] < 0.
 102
 103    When the above YYPACT, YYPGOTO, and YYCHECK tests determine that a
 104    value from YYTABLE should be used, that value is never zero, so it is
 105    useless to check for zero.  When those tests indicate that the value
 106    from YYDEFACT or YYDEFGOTO should be used instead, the value from
 107    YYTABLE *might* be zero, which, as a consequence of the way in which
 108    the tables are constructed, also happens to indicate that YYDEFACT or
 109    YYDEFGOTO should be used.  However, the YYTABLE value cannot be
 110    trusted when the YYDEFACT or YYDEFGOTO value should be used.  In
 111    summary, forget about zero values in YYTABLE.
 112 */
 113
 114 extern int nvectors;
 115
 116 typedef int base_number;
 117 extern base_number *base;
 118 /* A distinguished value of BASE, negative infinite.  During the
 119    computation equals to BASE_MINIMUM, later mapped to BASE_NINF to
 120    keep parser tables small.  */
 121 extern base_number base_ninf;
 122
 123 extern unsigned int *conflict_table;
 124 extern unsigned int *conflict_list;
 125 extern int conflict_list_cnt;
 126
 127 extern base_number *table;
 128 extern base_number *check;
 129 /* The value used in TABLE to denote explicit syntax errors
 130    (%nonassoc), a negative infinite.  */
 131 extern base_number table_ninf;
 132
 133 extern state_number *yydefgoto;
 134 extern rule_number *yydefact;
 135 extern int high;
 136
 137 void tables_generate (void);
 138 void tables_free (void);
 139
 140 #endif /* !TABLES_H_ */