X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/b2ed6e5826e772162719db595446b2c58e4ac5d6..0c2d3f4cba35c4bbea660794ab3cf91c030aafd3:/src/gram.h diff --git a/src/gram.h b/src/gram.h index 66031cc3..0a92993c 100644 --- a/src/gram.h +++ b/src/gram.h @@ -1,5 +1,6 @@ /* Data definitions for internal representation of bison's input, - Copyright 1984, 1986, 1989, 1992, 2001 Free Software Foundation, Inc. + Copyright (C) 1984, 1986, 1989, 1992, 2001, 2002 + Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -21,34 +22,56 @@ #ifndef GRAM_H_ # define GRAM_H_ -/* representation of the grammar rules: +/* Representation of the grammar rules: - ntokens is the number of tokens, and nvars is the number of - variables (nonterminals). nsyms is the total number, ntokens + + NTOKENS is the number of tokens, and NVARS is the number of + variables (nonterminals). NSYMS is the total number, ntokens + nvars. - (the true number of token values assigned is ntokens reduced by one - for each alias declaration) - Each symbol (either token or variable) receives a symbol number. - Numbers 0 to ntokens-1 are for tokens, and ntokens to nsyms-1 are - for variables. Symbol number zero is the end-of-input token. This - token is counted in ntokens. - - The rules receive rule numbers 1 to nrules in the order they are - written. Actions and guards are accessed via the rule number. + Numbers 0 to NTOKENS - 1 are for tokens, and NTOKENS to NSYMS - 1 + are for variables. Symbol number zero is the end-of-input token. + This token is counted in ntokens. The true number of token values + assigned is NTOKENS reduced by one for each alias declaration. + + The rules receive rule numbers 1 to NRULES in the order they are + written. More precisely Bison augments the grammar with the + initial rule, `$axiom: START-SYMBOL EOF', which is numbered 1, all + the user rules are 2, 3 etc. Each time a rule number is presented + to the user, we subtract 1, so *displayed* rule numbers are 0, 1, + 2... + + Internally, we cannot use the number 0 for a rule because for + instance RITEM stores both symbol (the RHS) and rule numbers: the + symbols are shorts >= 0, and rule number are stored negative. + Therefore 0 cannot be used, since it would be both the rule number + 0, and the token EOF). + + Actions are accessed via the rule number. The rules themselves are described by several arrays: amongst which - RITEM, and RULE_TABLE. + RITEM, and RULES. + + RULES is an array of struct rule_s, which members are: + + RULES[R].lhs -- the symbol of the left hand side of rule R. + + RULES[R].rhs -- the index in RITEM of the beginning of the portion + for rule R. + + RULES[R].prec -- the symbol providing the precedence level of R. - RULE_TABLE is an array of struct rule_s, which members are: + RULES[R].precsym -- the symbol attached (via %prec) to give its + precedence to R. Of course, if set, it is equal to `prec', but we + need to distinguish one from the other when reducing: a symbol used + in a %prec is not useless. - RULE_TABLE[R].lhs -- the symbol number of the left hand side of - rule R. If -1, the rule has been thrown out by reduce.c and should - be ignored. + RULES[R].assoc -- the associativity of R. - RULE_TABLE[R].rhs -- the index in RITEM of the beginning of the - portion for rule R. + RULES[R].line -- the line where R was defined. + + RULES[R].useful -- TRUE iff the rule is used (i.e., FALSE if thrown + away by reduce). The right hand side is stored as symbol numbers in a portion of RITEM. @@ -58,84 +81,105 @@ contains minus R, which identifies it as the end of a portion and says which rule it is for. - The portions of RITEM come in order of increasing rule number and - are followed by an element which is zero to mark the end. nitems - is the total length of ritem, not counting the final zero. Each - element of ritem is called an "item" and its index in ritem is an - item number. + The portions of RITEM come in order of increasing rule number. + NRITEMS is the total length of RITEM. Each element of RITEM is + called an "item" and its index in RITEM is an item number. Item numbers are used in the finite state machine to represent places that parsing can get to. - Precedence levels are recorded in the vectors sprec and rprec. - sprec records the precedence level of each symbol, rprec the - precedence level of each rule. rprecsym is the symbol-number of - the symbol in %prec for this rule (if any). + SYMBOLS[I]->prec records the precedence level of each symbol. Precedence levels are assigned in increasing order starting with 1 so that numerically higher precedence values mean tighter binding as they ought to. Zero as a symbol or rule's precedence means none is assigned. - Associativities are recorded similarly in rassoc and sassoc. */ + Associativities are recorded similarly in SYMBOLS[I]->assoc. */ +#include "symtab.h" #define ISTOKEN(s) ((s) < ntokens) #define ISVAR(s) ((s) >= ntokens) -extern int nitems; extern int nrules; extern int nsyms; extern int ntokens; extern int nvars; -extern short *ritem; +#define ITEM_NUMBER_MAX INT_MAX +typedef int item_number_t; +extern item_number_t *ritem; +extern unsigned int nritems; + +/* There is weird relationship between item_number_t and + token_number_t: we store token_number_t in item_number_t, but in + the latter we also store, as negative numbers, the rule numbers. + + Therefore, an token_number_t must be a valid item_number_t, and we + sometimes have to perform the converse transformation. */ +#define token_number_as_item_number(Tok) ((item_number_t) (Tok)) +#define item_number_as_token_number(Ite) ((token_number_t) (Ite)) -extern short *rprec; -extern short *rprecsym; -extern short *sprec; -extern short *rassoc; -extern short *sassoc; -extern short *rline; /* Source line number of each rule */ +extern token_number_t start_symbol; -extern int start_symbol; typedef struct rule_s { - short lhs; - short rhs; -} rule_t; + /* The number of the rule in the source. It is usually the index in + RULES too, except if there are useless rules. */ + short user_number; -extern struct rule_s *rule_table; + /* The index in RULES. Usually the rule number in the source, + except if some rules are useless. */ + short number; -/* associativity values in elements of rassoc, sassoc. */ -typedef enum -{ - right_assoc, - left_assoc, - non_assoc -} associativity; + symbol_t *lhs; + item_number_t *rhs; + /* This symbol provides both the associativity, and the precedence. */ + symbol_t *prec; -/* token translation table: indexed by a token number as returned by - the user's yylex routine, it yields the internal token number used - by the parser and throughout bison. */ + /* This symbol was attached to the rule via %prec. */ + symbol_t *precsym; -extern short *token_translations; -extern int max_user_token_number; + int line; + bool useful; + + const char *action; + int action_line; +} rule_t; + +extern struct rule_s *rules; + +/* Table of the symbols, indexed by the symbol number. */ +extern symbol_t **symbols; -/* SEMANTIC_PARSER is nonzero if the input file says to use the hairy - parser that provides for semantic error recovery. If it is zero, - the yacc-compatible simplified parser is used. */ +/* TOKEN_TRANSLATION -- a table indexed by a token number as returned + by the user's yylex routine, it yields the internal token number + used by the parser and throughout bison. */ +extern token_number_t *token_translations; +extern int max_user_token_number; -extern int semantic_parser; /* PURE_PARSER is nonzero if should generate a parser that is all pure and reentrant. */ extern int pure_parser; -/* ERROR_TOKEN_NUMBER is the token number of the error token. */ +/* Report the length of the RHS. */ +int rule_rhs_length PARAMS ((rule_t *rule)); + +/* Dump RITEM for traces. */ +void ritem_print PARAMS ((FILE *out)); + +/* Return the size of the longest rule RHS. */ +size_t ritem_longest_rhs PARAMS ((void)); + +/* Dump the grammar. */ +void grammar_dump PARAMS ((FILE *out, const char *title)); + +/* Free the packed grammar. */ +void grammar_free PARAMS ((void)); -extern int error_token_number; #endif /* !GRAM_H_ */