126 lines
4.3 KiB
C
126 lines
4.3 KiB
C
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/* Data definitions for internal representation of bison's input,
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Copyright (C) 1984, 1986, 1989, 1992 Free Software Foundation, Inc.
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This file is part of Bison, the GNU Compiler Compiler.
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Bison is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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Bison is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Bison; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* representation of the grammar rules:
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ntokens is the number of tokens, and nvars is the number of variables
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(nonterminals). nsyms is the total number, ntokens + nvars.
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(the true number of token values assigned is ntokens
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reduced by one for each alias declaration)
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Each symbol (either token or variable) receives a symbol number.
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Numbers 0 to ntokens-1 are for tokens, and ntokens to nsyms-1 are for
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variables. Symbol number zero is the end-of-input token. This token
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is counted in ntokens.
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The rules receive rule numbers 1 to nrules in the order they are written.
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Actions and guards are accessed via the rule number.
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The rules themselves are described by three arrays: rrhs, rlhs and
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ritem. rlhs[R] is the symbol number of the left hand side of rule R.
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The right hand side is stored as symbol numbers in a portion of
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ritem. rrhs[R] contains the index in ritem of the beginning of the
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portion for rule R.
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If rlhs[R] is -1, the rule has been thrown out by reduce.c
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and should be ignored.
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The length of the portion is one greater
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than the number of symbols in the rule's right hand side.
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The last element in the portion contains minus R, which
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identifies it as the end of a portion and says which rule it is for.
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The portions of ritem come in order of increasing rule number and are
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followed by an element which is zero to mark the end. nitems is the
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total length of ritem, not counting the final zero. Each element of
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ritem is called an "item" and its index in ritem is an item number.
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Item numbers are used in the finite state machine to represent
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places that parsing can get to.
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Precedence levels are recorded in the vectors sprec and rprec.
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sprec records the precedence level of each symbol,
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rprec the precedence level of each rule.
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rprecsym is the symbol-number of the symbol in %prec for this rule (if any).
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Precedence levels are assigned in increasing order starting with 1 so
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that numerically higher precedence values mean tighter binding as they
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ought to. Zero as a symbol or rule's precedence means none is
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assigned.
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Associativities are recorded similarly in rassoc and sassoc. */
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#define ISTOKEN(s) ((s) < ntokens)
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#define ISVAR(s) ((s) >= ntokens)
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extern int nitems;
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extern int nrules;
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extern int nsyms;
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extern int ntokens;
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extern int nvars;
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extern short *ritem;
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extern short *rlhs;
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extern short *rrhs;
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extern short *rprec;
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extern short *rprecsym;
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extern short *sprec;
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extern short *rassoc;
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extern short *sassoc;
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extern short *rline; /* Source line number of each rule */
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extern int start_symbol;
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/* associativity values in elements of rassoc, sassoc. */
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#define RIGHT_ASSOC 1
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#define LEFT_ASSOC 2
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#define NON_ASSOC 3
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/* token translation table:
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indexed by a token number as returned by the user's yylex routine,
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it yields the internal token number used by the parser and throughout bison.
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If translations is zero, the translation table is not used because
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the two kinds of token numbers are the same.
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(It is noted in reader.c that "Nowadays translations is always set to 1...")
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*/
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extern short *token_translations;
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extern int translations;
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extern int max_user_token_number;
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/* semantic_parser is nonzero if the input file says to use the hairy parser
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that provides for semantic error recovery. If it is zero, the yacc-compatible
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simplified parser is used. */
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extern int semantic_parser;
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/* pure_parser is nonzero if should generate a parser that is all pure and reentrant. */
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extern int pure_parser;
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/* error_token_number is the token number of the error token. */
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extern int error_token_number;
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