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 are accessed via the rule number.
RULES[R].assoc -- the associativity of R.
- RULES[R].dprec -- the dynamic precedence level of R (for GLR parsing).
+ 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].merger -- index of merging function for R (for GLR
+ parsing).
RULES[R].line -- the line where R was defined.
# define ISTOKEN(s) ((s) < ntokens)
# define ISVAR(s) ((s) >= ntokens)
-extern int nrules;
extern int nsyms;
extern int ntokens;
extern int nvars;
-# define ITEM_NUMBER_MAX INT_MAX
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 item_number_t and
- symbol_number_t: we store symbol_number_t in item_number_t, but in
- the latter we also store, as negative numbers, the rule numbers.
+/* 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. */
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;
item_number_t *rhs;
extern struct rule_s *rules;
+/* A function that selects a rule. */
+typedef bool (*rule_filter_t) PARAMS ((rule_t *r));
+
+/* Return true IFF the rule has a `number' smaller than NRULES. */
+bool rule_useful_p PARAMS ((rule_t *r));
+
+/* Return true IFF the rule has a `number' higher than NRULES. */
+bool rule_useless_p PARAMS ((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 PARAMS ((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 PARAMS ((rule_t *rule, symbol_t *previous_lhs, FILE *out));
+
+/* Return the length of the RHS. */
+int rule_rhs_length PARAMS ((rule_t *rule));
+
+/* Print this RULE's RHS on OUT. */
+void rule_rhs_print PARAMS ((rule_t *rule, FILE *out));
+
+/* Print this RULE on OUT. */
+void rule_print PARAMS ((rule_t *rule, FILE *out));
+
+
+
+
/* Table of the symbols, indexed by the symbol number. */
extern symbol_t **symbols;
extern int max_user_token_number;
+
/* 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 pure_parser;
-/* Return the length of the RHS. */
-int rule_rhs_length PARAMS ((rule_t *rule));
-
-/* Print this RULE's RHS on OUT. */
-void rule_rhs_print PARAMS ((rule_t *rule, FILE *out));
-
-/* Print this RULE on OUT. */
-void rule_print PARAMS ((rule_t *rule, FILE *out));
-
/* Dump RITEM for traces. */
void ritem_print PARAMS ((FILE *out));
/* Print the grammar's rules numbers from BEGIN (inclusive) to END
(exclusive) on OUT under TITLE. */
void grammar_rules_partial_print PARAMS ((FILE *out, const char *title,
- int begin, int end));
+ rule_filter_t filter));
/* Print the grammar's rules on OUT. */
void grammar_rules_print PARAMS ((FILE *out));
/* Dump the grammar. */
void grammar_dump PARAMS ((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 PARAMS ((const char *message));
+
/* Free the packed grammar. */
void grammar_free PARAMS ((void));
projects / bison.git / blobdiff