src/tables.h

   1 /* Prepare the LALR and GLR parser tables.
   2
   3    Copyright (C) 2002, 2004, 2009-2015 Free Software Foundation, Inc.
   4
   5    This file is part of Bison, the GNU Compiler Compiler.
   6
   7    This program is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation, either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef TABLES_H_
  21 # define TABLES_H_
  22
  23 # include "state.h"
  24
  25 /* The parser tables consist of these tables.
  26
  27    YYTRANSLATE = vector mapping yylex's token numbers into bison's
  28    token numbers.
  29
  30    YYTNAME = vector of string-names indexed by bison token number.
  31
  32    YYTOKNUM = vector of yylex token numbers corresponding to entries
  33    in YYTNAME.
  34
  35    YYRLINE = vector of line-numbers of all rules.  For yydebug
  36    printouts.
  37
  38    YYRHS = vector of items of all rules.  This is exactly what RITEMS
  39    contains.  For yydebug and for semantic parser.
  40
  41    YYPRHS[R] = index in YYRHS of first item for rule R.
  42
  43    YYR1[R] = symbol number of symbol that rule R derives.
  44
  45    YYR2[R] = number of symbols composing right hand side of rule R.
  46
  47    YYSTOS[S] = the symbol number of the symbol that leads to state S.
  48
  49    YYFINAL = the state number of the termination state.
  50
  51    YYTABLE = a vector filled with portions for different uses, found
  52    via YYPACT and YYPGOTO, described below.
  53
  54    YYLAST ( = high) the number of the last element of YYTABLE, i.e.,
  55    sizeof (YYTABLE) - 1.
  56
  57    YYCHECK = a vector indexed in parallel with YYTABLE.  It indicates,
  58    in a roundabout way, the bounds of the portion you are trying to
  59    examine.
  60
  61    Suppose that the portion of YYTABLE starts at index P and the index
  62    to be examined within the portion is I.  Then if YYCHECK[P+I] != I,
  63    I is outside the bounds of what is actually allocated, and the
  64    default (from YYDEFACT or YYDEFGOTO) should be used.  Otherwise,
  65    YYTABLE[P+I] should be used.
  66
  67    YYDEFACT[S] = default reduction number in state s.  Performed when
  68    YYTABLE doesn't specify something else to do.  Zero means the default
  69    is an error.
  70
  71    YYDEFGOTO[I] = default state to go to after a reduction of a rule
  72    that generates variable NTOKENS + I, except when YYTABLE specifies
  73    something else to do.
  74
  75    YYPACT[S] = index in YYTABLE of the portion describing state S.
  76    The lookahead token's number, I, is used to index that portion of
  77    YYTABLE to find out what action to perform.
  78
  79    If YYPACT[S] == YYPACT_NINF, if YYPACT[S] + I is outside the bounds
  80    of YYTABLE (from 0 to YYLAST), or I is outside the bounds for portion
  81    S (that is, YYCHECK[YYPACT[S] + I] != I), then the default action
  82    (that is, YYDEFACT[S]) should be used instead of YYTABLE.  Otherwise,
  83    the value YYTABLE[YYPACT[S] + I] should be used even if
  84    YYPACT[S] < 0.
  85
  86    If the value in YYTABLE is positive, we shift the token and go to
  87    that state.
  88
  89    If the value is negative, it is minus a rule number to reduce by.
  90
  91    If the value is YYTABLE_NINF, it's a syntax error.
  92
  93    YYPGOTO[I] = the index in YYTABLE of the portion describing what to
  94    do after reducing a rule that derives variable I + NTOKENS.  This
  95    portion is indexed by the parser state number, S, as of before the
  96    text for this nonterminal was read.
  97
  98    If YYPGOTO[I] + S is outside the bounds of YYTABLE (from 0 to YYLAST)
  99    or if S is outside the bounds of the portion for I (that is,
 100    YYCHECK[YYPGOTO[I] + S] != S), then the default state (that is,
 101    YYDEFGOTO[I]) should be used instead of YYTABLE.  Otherwise,
 102    YYTABLE[YYPGOTO[I] + S] is the state to go to even if YYPGOTO[I] < 0.
 103
 104    When the above YYPACT, YYPGOTO, and YYCHECK tests determine that a
 105    value from YYTABLE should be used, that value is never zero, so it is
 106    useless to check for zero.  When those tests indicate that the value
 107    from YYDEFACT or YYDEFGOTO should be used instead, the value from
 108    YYTABLE *might* be zero, which, as a consequence of the way in which
 109    the tables are constructed, also happens to indicate that YYDEFACT or
 110    YYDEFGOTO should be used.  However, the YYTABLE value cannot be
 111    trusted when the YYDEFACT or YYDEFGOTO value should be used.  In
 112    summary, forget about zero values in YYTABLE.
 113 */
 114
 115 extern int nvectors;
 116
 117 typedef int base_number;
 118 extern base_number *base;
 119 /* A distinguished value of BASE, negative infinite.  During the
 120    computation equals to BASE_MINIMUM, later mapped to BASE_NINF to
 121    keep parser tables small.  */
 122 extern base_number base_ninf;
 123
 124 extern unsigned int *conflict_table;
 125 extern unsigned int *conflict_list;
 126 extern int conflict_list_cnt;
 127
 128 extern base_number *table;
 129 extern base_number *check;
 130 /* The value used in TABLE to denote explicit syntax errors
 131    (%nonassoc), a negative infinite.  */
 132 extern base_number table_ninf;
 133
 134 extern state_number *yydefgoto;
 135 extern rule_number *yydefact;
 136 extern int high;
 137
 138 void tables_generate (void);
 139 void tables_free (void);
 140
 141 #endif /* !TABLES_H_ */