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[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 (i.e., FALSE if thrown
+ 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
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 "symtab.h"
+# include "location.h"
+# include "symtab.h"
-#define ISTOKEN(s) ((s) < ntokens)
-#define ISVAR(s) ((s) >= ntokens)
+# 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;
-extern int nritems;
+typedef int item_number_t;
+# define ITEM_NUMBER_MAX ((item_number_t) INT_MAX)
+# define ITEM_NUMBER_MIN ((item_number_t) INT_MIN)
+extern item_number_t *ritem;
+extern unsigned int nritems;
+
+/* There is weird relationship between OT1H item_number_t and OTOH
+ symbol_number_t and rule_number_t: we store the latter in
+ item_number_t. symbol_number_t are stored as are, while
+ the negation of (rule_number_t + 1) are stored.
+
+ Therefore, an symbol_number_t must be a valid item_number_t, and we
+ sometimes have to perform the converse transformation. */
+# define symbol_number_as_item_number(Tok) ((item_number_t) (Tok))
+# define item_number_as_symbol_number(Ite) ((symbol_number_t) (Ite))
-extern int start_symbol;
+extern symbol_number_t start_symbol;
+
+/* Rules numbers. */
+typedef short rule_number_t;
+# define RULE_NUMBER_MAX ((rule_number_t) SHRT_MAX)
+extern rule_number_t nrules;
+# define int_of_rule_number(RNum) ((int) (RNum))
+# define rule_number_as_item_number(RNum) ((item_number_t) (- RNum - 1))
+# define item_number_as_rule_number(INum) ((rule_number_t) (- INum - 1))
+
+
+/*--------.
+| Rules. |
+`--------*/
typedef struct rule_s
{
/* 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;
+ rule_number_t user_number;
/* The index in RULES. Usually the rule number in the source,
except if some rules are useless. */
- short number;
+ rule_number_t number;
symbol_t *lhs;
- short *rhs;
+ item_number_t *rhs;
/* This symbol provides both the associativity, and the precedence. */
symbol_t *prec;
+ short dprec;
+ short merger;
+
/* This symbol was attached to the rule via %prec. */
symbol_t *precsym;
- short line;
+ location_t location;
bool useful;
const char *action;
- short action_line;
-
- const char *guard;
- short guard_line;
+ location_t action_location;
} rule_t;
extern struct rule_s *rules;
+/* A function that selects a rule. */
+typedef bool (*rule_filter_t) (rule_t *r);
+
+/* Return true IFF the rule has a `number' smaller than NRULES. */
+bool rule_useful_p (rule_t *r);
+
+/* Return true IFF the rule has a `number' higher than NRULES. */
+bool rule_useless_p (rule_t *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_t *r);
+
+/* 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_t *rule, symbol_t *previous_lhs, FILE *out);
+
+/* Return the length of the RHS. */
+int rule_rhs_length (rule_t *rule);
+
+/* Print this RULE's RHS on OUT. */
+void rule_rhs_print (rule_t *rule, FILE *out);
+
+/* Print this RULE on OUT. */
+void rule_print (rule_t *rule, FILE *out);
+
+
+
+
/* Table of the symbols, indexed by the symbol number. */
extern symbol_t **symbols;
-/* 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 short *token_translations;
+/* 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_t *token_translations;
extern int max_user_token_number;
-/* 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. */
-extern int semantic_parser;
+
+/* GLR_PARSER is nonzero if the input file says to use the GLR
+ (Generalized LR) parser, and to output some additional
+ information used by the GLR algorithm. */
+
+extern int glr_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. */
+/* Dump RITEM for traces. */
+void ritem_print (FILE *out);
-extern int error_token_number;
+/* Return the size of the longest rule RHS. */
+size_t ritem_longest_rhs (void);
-/* Report the length of the RHS. */
-int rule_rhs_length PARAMS ((rule_t *rule));
+/* 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_t filter);
-/* Dump RITEM for traces. */
-void ritem_print PARAMS ((FILE *out));
+/* Print the grammar's rules on OUT. */
+void grammar_rules_print (FILE *out);
-/* Return the size of the longest rule RHS. */
-size_t ritem_longest_rhs PARAMS ((void));
+/* 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