projects / bison.git / blame
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| f7d4d87a DM |
1 | /* Data definitions for internal representation of bison's input, |
| 2 | Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc. | |
| 3 | ||
| 4 | This file is part of Bison, the GNU Compiler Compiler. | |
| 5 | ||
| 6 | Bison 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 2, or (at your option) | |
| 9 | any later version. | |
| 10 | ||
| 11 | Bison 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 Bison; see the file COPYING. If not, write to | |
| 18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
| 19 | ||
| 20 | ||
| 21 | /* representation of the grammar rules: | |
| 22 | ||
| 23 | ntokens is the number of tokens, and nvars is the number of variables | |
| 24 | (nonterminals). nsyms is the total number, ntokens + nvars. | |
| 25 | ||
| 26 | Each symbol (either token or variable) receives a symbol number. | |
| 27 | Numbers 0 to ntokens-1 are for tokens, and ntokens to nsyms-1 are for | |
| 28 | variables. Symbol number zero is the end-of-input token. This token | |
| 29 | is counted in ntokens. | |
| 30 | ||
| 31 | The rules receive rule numbers 1 to nrules in the order they are written. | |
| 32 | Actions and guards are accessed via the rule number. | |
| 33 | ||
| 34 | The rules themselves are described by three arrays: rrhs, rlhs and | |
| 35 | ritem. rlhs[R] is the symbol number of the left hand side of rule R. | |
| 36 | The right hand side is stored as symbol numbers in a portion of | |
| 37 | ritem. rrhs[R] contains the index in ritem of the beginning of the | |
| 38 | portion for rule R. | |
| 39 | ||
| 40 | If rlhs[R] is -1, the rule has been thrown out by reduce.c | |
| 41 | and should be ignored. | |
| 42 | ||
| 43 | The length of the portion is one greater | |
| 44 | than the number of symbols in the rule's right hand side. | |
| 45 | The last element in the portion contains minus R, which | |
| 46 | identifies it as the end of a portion and says which rule it is for. | |
| 47 | ||
| 48 | The portions of ritem come in order of increasing rule number and are | |
| 49 | followed by an element which is zero to mark the end. nitems is the | |
| 50 | total length of ritem, not counting the final zero. Each element of | |
| 51 | ritem is called an "item" and its index in ritem is an item number. | |
| 52 | ||
| 53 | Item numbers are used in the finite state machine to represent | |
| 54 | places that parsing can get to. | |
| 55 | ||
| 56 | Precedence levels are recorded in the vectors sprec and rprec. | |
| 57 | sprec records the precedence level of each symbol, | |
| 58 | rprec the precedence level of each rule. | |
| 59 | rprecsym is the symbol-number of the symbol in %prec for this rule (if any). | |
| 60 | ||
| 61 | Precedence levels are assigned in increasing order starting with 1 so | |
| 62 | that numerically higher precedence values mean tighter binding as they | |
| 63 | ought to. Zero as a symbol or rule's precedence means none is | |
| 64 | assigned. | |
| 65 | ||
| 66 | Associativities are recorded similarly in rassoc and sassoc. */ | |
| 67 | ||
| 68 | ||
| 69 | #define ISTOKEN(s) ((s) < ntokens) | |
| 70 | #define ISVAR(s) ((s) >= ntokens) | |
| 71 | ||
| 72 | ||
| 73 | extern int nitems; | |
| 74 | extern int nrules; | |
| 75 | extern int nsyms; | |
| 76 | extern int ntokens; | |
| 77 | extern int nvars; | |
| 78 | ||
| 79 | extern short *ritem; | |
| 80 | extern short *rlhs; | |
| 81 | extern short *rrhs; | |
| 82 | extern short *rprec; | |
| 83 | extern short *rprecsym; | |
| 84 | extern short *sprec; | |
| 85 | extern short *rassoc; | |
| 86 | extern short *sassoc; | |
| 87 | extern short *rline; /* Source line number of each rule */ | |
| 88 | ||
| 89 | extern int start_symbol; | |
| 90 | ||
| 91 | ||
| 92 | /* associativity values in elements of rassoc, sassoc. */ | |
| 93 | ||
| 94 | #define RIGHT_ASSOC 1 | |
| 95 | #define LEFT_ASSOC 2 | |
| 96 | #define NON_ASSOC 3 | |
| 97 | ||
| 98 | /* token translation table: | |
| 99 | indexed by a token number as returned by the user's yylex routine, | |
| 100 | it yields the internal token number used by the parser and throughout bison. | |
| 101 | If translations is zero, the translation table is not used because | |
| 102 | the two kinds of token numbers are the same. */ | |
| 103 | ||
| 104 | extern short *token_translations; | |
| 105 | extern int translations; | |
| 106 | extern int max_user_token_number; | |
| 107 | ||
| 108 | /* semantic_parser is nonzero if the input file says to use the hairy parser | |
| 109 | that provides for semantic error recovery. If it is zero, the yacc-compatible | |
| 110 | simplified parser is used. */ | |
| 111 | ||
| 112 | extern int semantic_parser; | |
| 113 | ||
| 114 | /* pure_parser is nonzero if should generate a parser that is all pure and reentrant. */ | |
| 115 | ||
| 116 | extern int pure_parser; | |
| 117 | ||
| 118 | /* error_token_number is the token number of the error token. */ | |
| 119 | ||
| 120 | extern int error_token_number; |