-/* 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, 2004
+ Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
The rules receive rule numbers 1 to NRULES in the order they are
written. More precisely Bison augments the grammar with the
- initial rule, `$axiom: START-SYMBOL EOF', which is numbered 1, all
- the user rules are 2, 3 etc. Each time a rule number is presented
- to the user, we subtract 1, so *displayed* rule numbers are 0, 1,
- 2...
+ initial rule, `$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 EOF).
+ 0, and the token $end).
- Actions and guards are accessed via the rule number.
+ Actions are accessed via the rule number.
The rules themselves are described by several arrays: amongst which
RITEM, and RULES.
- RULES is an array of struct rule_s, which members are:
+ RULES is an array of rules, whose members are:
- RULES[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].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 precedence level of R.
+ RULES[R].prec -- the symbol providing the precedence level of R.
- RULES[R].precsym -- the symbol-number of the symbol in %prec for R
- (if any).
+ 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.
RULES[R].assoc -- the associativity of R.
+ RULES[R].dprec -- the dynamic precedence level of R (for GLR
+ parsing).
+
+ RULES[R].merger -- index of merging function for R (for GLR
+ parsing).
+
RULES[R].line -- the line where R was defined.
- RULES[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.
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;
-extern int nritems;
+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;
+}
+
+/* Rule numbers. */
+typedef int 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 for tokens and rules. */
-typedef enum
+static inline rule_number
+item_number_as_rule_number (item_number i)
{
- right_assoc,
- left_assoc,
- non_assoc
-} associativity;
+ return -1 - i;
+}
+
+/*--------.
+| Rules. |
+`--------*/
-typedef struct rule_s
+typedef struct
{
- short lhs;
- short rhs;
- short prec;
- short precsym;
- associativity 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;
+
+ int dprec;
+ int merger;
+
+ /* This symbol was attached to the rule via %prec. */
+ symbol *precsym;
+
+ location location;
bool useful;
const char *action;
- short action_line;
+ location action_location;
+} rule;
- const char *guard;
- short guard_line;
-} rule_t;
+extern rule *rules;
-extern struct rule_s *rules;
+/* A function that selects a rule. */
+typedef bool (*rule_filter) (rule *);
-/* Table of the symbols, indexed by the symbol number. */
-extern struct bucket **symbols;
+/* Return true IFF the rule has a `number' smaller than NRULES. */
+bool rule_useful_p (rule *r);
-/* 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. */
+/* Return true IFF the rule has a `number' higher than NRULES. */
+bool rule_useless_p (rule *r);
-extern short *token_translations;
-extern int max_user_token_number;
+/* 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 PARAMS ((FILE *out));
+void ritem_print (FILE *out);
/* Return the size of the longest rule RHS. */
-size_t ritem_longest_rhs PARAMS ((void));
+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_ */
projects / bison.git / blobdiff