-/* Data definitions for internal representation of bison's input,
- Copyright 1984, 1986, 1989, 1992, 2001 Free Software Foundation, Inc.
+/* Data definitions for internal representation of Bison's input.
+
+ Copyright (C) 1984, 1986, 1989, 1992, 2001, 2002, 2003
+ Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
#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, `$accept: START-SYMBOL $end', 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 $end).
+
+ 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 rules, whose members are:
+
+ RULES[R].lhs -- the symbol of the left hand side of rule R.
- RULE_TABLE is an array of struct rule_s, which members are:
+ RULES[R].rhs -- the index in RITEM of the beginning of the portion
+ for rule R.
- 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].prec -- the symbol providing the precedence level of R.
- RULE_TABLE[R].rhs -- the index in RITEM of the beginning of the
- portion for rule R.
+ 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].prec -- the precedence level of R.
+ RULES[R].assoc -- the associativity of R.
- RULE_TABLE[R].precsym -- the symbol-number of the symbol in %prec
- for R (if any).
+ RULES[R].dprec -- the dynamic precedence level of R (for GLR
+ parsing).
- RULE_TABLE[R].assoc -- the associativity of R.
+ RULES[R].merger -- index of merging function for R (for GLR
+ parsing).
- RULE_TABLE[R].line -- the line where R was defined.
+ RULES[R].line -- the line where R was defined.
- RULE_TABLE[R].useful -- TRUE iff the rule is used.
+ 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.
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.
- SPREC records the precedence level of each symbol.
+ 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 "location.h"
+# include "symtab.h"
-#define ISTOKEN(s) ((s) < ntokens)
-#define ISVAR(s) ((s) >= ntokens)
+# define ISTOKEN(i) ((i) < ntokens)
+# define ISVAR(i) ((i) >= ntokens)
-extern int nitems;
-extern int nrules;
extern int nsyms;
extern int ntokens;
extern int nvars;
-extern short *ritem;
+typedef int item_number;
+extern item_number *ritem;
+extern unsigned int nritems;
+
+/* There is weird relationship between OT1H item_number and OTOH
+ symbol_number and rule_number: we store the latter in
+ item_number. symbol_number values are stored as-is, while
+ the negation of (rule_number + 1) is stored.
+
+ Therefore, a symbol_number must be a valid item_number, and we
+ sometimes have to perform the converse transformation. */
+
+static inline item_number
+symbol_number_as_item_number (symbol_number sym)
+{
+ return sym;
+}
+
+static inline symbol_number
+item_number_as_symbol_number (item_number i)
+{
+ return i;
+}
-extern short *sprec;
-extern short *sassoc;
+/* Rule numbers. */
+typedef short rule_number;
+extern rule_number nrules;
-extern int start_symbol;
+static inline item_number
+rule_number_as_item_number (rule_number r)
+{
+ return -1 - r;
+}
-/* associativity values in elements of rassoc, sassoc. */
-typedef enum
+static inline rule_number
+item_number_as_rule_number (item_number i)
{
- right_assoc,
- left_assoc,
- non_assoc
-} associativity;
+ return -1 - i;
+}
-typedef struct rule_s
+/*--------.
+| Rules. |
+`--------*/
+
+typedef struct
{
- short lhs;
- short rhs;
- short prec;
- short precsym;
- short assoc;
- short line;
+ /* The number of the rule in the source. It is usually the index in
+ RULES too, except if there are useless rules. */
+ rule_number user_number;
+
+ /* The index in RULES. Usually the rule number in the source,
+ except if some rules are useless. */
+ rule_number number;
+
+ symbol *lhs;
+ item_number *rhs;
+
+ /* This symbol provides both the associativity, and the precedence. */
+ symbol *prec;
+
+ short dprec;
+ short merger;
+
+ /* This symbol was attached to the rule via %prec. */
+ symbol *precsym;
+
+ location location;
bool useful;
-} rule_t;
-extern struct rule_s *rule_table;
+ const char *action;
+ location action_location;
+} rule;
-/* 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. */
+extern rule *rules;
-extern short *token_translations;
-extern int max_user_token_number;
+/* A function that selects a rule. */
+typedef bool (*rule_filter) (rule *);
+
+/* Return true IFF the rule has a `number' smaller than NRULES. */
+bool rule_useful_p (rule *r);
+
+/* Return true IFF the rule has a `number' higher than NRULES. */
+bool rule_useless_p (rule *r);
+
+/* Return true IFF the rule is not flagged as useful *and* is useful.
+ In other words, it was discarded because of conflicts. */
+bool rule_never_reduced_p (rule *r);
-/* 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. */
+/* Print this rule's number and lhs on OUT. If a PREVIOUS_LHS was
+ already displayed (by a previous call for another rule), avoid
+ useless repetitions. */
+void rule_lhs_print (rule *r, symbol *previous_lhs, FILE *out);
-extern int semantic_parser;
+/* Return the length of the RHS. */
+int rule_rhs_length (rule *r);
-/* PURE_PARSER is nonzero if should generate a parser that is all pure
- and reentrant. */
+/* Print this rule's RHS on OUT. */
+void rule_rhs_print (rule *r, FILE *out);
-extern int pure_parser;
+/* Print this rule on OUT. */
+void rule_print (rule *r, FILE *out);
-/* ERROR_TOKEN_NUMBER is the token number of the error token. */
-extern int error_token_number;
+
+
+/* Table of the symbols, indexed by the symbol number. */
+extern symbol **symbols;
+
+/* 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 symbol_number *token_translations;
+extern int max_user_token_number;
+
/* Dump RITEM for traces. */
void ritem_print (FILE *out);
+
+/* Return the size of the longest rule RHS. */
+size_t ritem_longest_rhs (void);
+
+/* Print the grammar's rules numbers from BEGIN (inclusive) to END
+ (exclusive) on OUT under TITLE. */
+void grammar_rules_partial_print (FILE *out, const char *title,
+ rule_filter filter);
+
+/* Print the grammar's rules on OUT. */
+void grammar_rules_print (FILE *out);
+
+/* Dump the grammar. */
+void grammar_dump (FILE *out, const char *title);
+
+/* Report on STDERR the rules that are not flagged USEFUL, using the
+ MESSAGE (which can be `useless rule' when invoked after grammar
+ reduction, or `never reduced' after conflicts were taken into
+ account). */
+void grammar_rules_never_reduced_report (const char *message);
+
+/* Free the packed grammar. */
+void grammar_free (void);
+
#endif /* !GRAM_H_ */
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