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Annotation of researchv10dc/cmd/bison/gram.h, revision 1.1

1.1     ! root        1: /* Data definitions for internal representation of bison's input,
        !             2:    Copyright (C) 1984, 1986 Bob Corbett and Free Software Foundation, Inc.
        !             3: 
        !             4: BISON is distributed in the hope that it will be useful, but WITHOUT ANY
        !             5: WARRANTY.  No author or distributor accepts responsibility to anyone
        !             6: for the consequences of using it or for whether it serves any
        !             7: particular purpose or works at all, unless he says so in writing.
        !             8: Refer to the BISON General Public License for full details.
        !             9: 
        !            10: Everyone is granted permission to copy, modify and redistribute BISON,
        !            11: but only under the conditions described in the BISON General Public
        !            12: License.  A copy of this license is supposed to have been given to you
        !            13: along with BISON so you can know your rights and responsibilities.  It
        !            14: should be in a file named COPYING.  Among other things, the copyright
        !            15: notice and this notice must be preserved on all copies.
        !            16: 
        !            17:  In other words, you are welcome to use, share and improve this program.
        !            18:  You are forbidden to forbid anyone else to use, share and improve
        !            19:  what you give them.   Help stamp out software-hoarding!  */
        !            20: 
        !            21: /* representation of the grammar rules:
        !            22: 
        !            23: ntokens is the number of tokens, and nvars is the number of variables (nonterminals).
        !            24: 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 variables.
        !            28: Symbol number zero is the end-of-input token.  This token is counted in ntokens.
        !            29: 
        !            30: The rules receive rule numbers 1 to nrules in the order they are written.
        !            31: Actions and guards are accessed via the rule number.
        !            32: 
        !            33: The rules themselves are described by three arrays: rrhs, rlhs and ritems.
        !            34: rlhs[r] is the symbol number of the left hand side of rule r.
        !            35: The right hand side is stored as symbol numbers in a portion of ritems.
        !            36: rrhs[r] contains the index in ritems of the beginning of the portion for rule r.
        !            37: The length of the portion is one greater
        !            38:  than the number of symbols in the rule's right hand side.
        !            39: The last element in the portion contains minus r, which
        !            40: identifies it as the end of a portion and says which rule it is for.
        !            41: 
        !            42: The portions of ritems come in order of increasing rule number and are
        !            43: followed by an element which is zero to mark the end.  nitems is the
        !            44: total length of ritems, not counting the final zero.  Each element of
        !            45: ritems is called an "item" and its index in ritems is an item number.
        !            46: 
        !            47: Item numbers are used in the finite state machine to represent
        !            48: places that parsing can get to.
        !            49: 
        !            50: Precedence levels are recorded in the vectors sprec and rprec.
        !            51: sprec records the precedence level of each symbol,
        !            52: rprec the precedence level of each rule.
        !            53: 
        !            54: Precedence levels are assigned in increasing order starting with 1
        !            55: so that numerically higher precedence values mean tighter binding
        !            56: as they ought to.  Zero as a symbol or rule's precedence means none is assigned.
        !            57: 
        !            58: Associativities are recorded similarly in rassoc and sassoc.  */
        !            59: 
        !            60: 
        !            61: #define        ISTOKEN(s)      ((s) < ntokens)
        !            62: #define        ISVAR(s)        ((s) >= ntokens)
        !            63: 
        !            64: 
        !            65: extern int nitems;
        !            66: extern int nrules;
        !            67: extern int nsyms;
        !            68: extern int ntokens;
        !            69: extern int nvars;
        !            70: 
        !            71: extern short *ritem;
        !            72: extern short *rlhs;
        !            73: extern short *rrhs;
        !            74: extern short *rprec;
        !            75: extern short *sprec;
        !            76: extern short *rassoc;
        !            77: extern short *sassoc;
        !            78: extern short *rline;           /* Source line number of each rule */
        !            79: 
        !            80: extern int start_symbol;
        !            81: 
        !            82: 
        !            83: /* associativity values in elements of rassoc, sassoc.  */
        !            84: 
        !            85: #define RIGHT_ASSOC 1
        !            86: #define LEFT_ASSOC 2
        !            87: #define NON_ASSOC 3
        !            88: 
        !            89: /* token translation table:
        !            90: indexed by a token number as returned by the user's yylex routine,
        !            91: it yields the internal token number used by the parser and throughout bison.
        !            92: If translations is zero, the translation table is not used because
        !            93: the two kinds of token numbers are the same.  */
        !            94: 
        !            95: extern short *token_translations;
        !            96: extern int translations;
        !            97: extern int max_user_token_number;
        !            98: 
        !            99: /* semantic_parser is nonzero if the input file says to use the hairy parser
        !           100: that provides for semantic error recovery.  If it is zero, the yacc-compatible
        !           101: simplified parser is used.  */
        !           102: 
        !           103: extern int semantic_parser;
        !           104: 
        !           105: /* pure_parser is nonzero if should generate a parser that is all pure and reentrant. */
        !           106: 
        !           107: extern int pure_parser;
        !           108: 
        !           109: /* error_token_number is the token number of the error token.  */
        !           110: 
        !           111: extern int error_token_number;

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