X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/680e8701b5ad9718f18f1493e30134b52bceaaca..cce7a5f4230618ddc7e256e8b83b7f0d84ff5909:/src/gram.h

diff --git a/src/gram.h b/src/gram.h
index 9ae10b8b..e7cf33d6 100644
--- a/src/gram.h
+++ b/src/gram.h
@@ -1,4 +1,5 @@
-/* Data definitions for internal representation of bison's input,
+/* Data definitions for internal representation of Bison's input.
+
    Copyright (C) 1984, 1986, 1989, 1992, 2001, 2002
    Free Software Foundation, Inc.
 
@@ -36,23 +37,23 @@
 
    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 of the left hand side of rule R.
 
@@ -68,9 +69,15 @@
 
    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
@@ -81,11 +88,9 @@
    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.  nritems
-   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.
@@ -99,84 +104,170 @@
 
    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 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 s)
+{
+  return s;
+}
+
+static inline symbol_number
+item_number_as_symbol_number (item_number i)
+{
+  return i;
+}
+
+extern symbol_number start_symbol;
+
+/* 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;
+}
 
-typedef struct rule_s
+static inline rule_number
+item_number_as_rule_number (item_number i)
+{
+  return -1 - i;
+}
+
+
+/*--------.
+| Rules.  |
+`--------*/
+
+typedef struct
 {
   /* 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 user_number;
 
   /* The index in RULES.  Usually the rule number in the source,
      except if some rules are useless.  */
-  short number;
+  rule_number number;
 
-  symbol_t *lhs;
-  short *rhs;
+  symbol *lhs;
+  item_number *rhs;
 
   /* This symbol provides both the associativity, and the precedence. */
-  symbol_t *prec;
+  symbol *prec;
+
+  short dprec;
+  short merger;
 
   /* This symbol was attached to the rule via %prec. */
-  symbol_t *precsym;
+  symbol *precsym;
 
-  short line;
+  location location;
   bool useful;
 
   const char *action;
-  short action_line;
+  location action_location;
+} rule;
+
+extern rule *rules;
+
+/* 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);
+
+/* 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);
+
+/* Return the length of the RHS.  */
+int rule_rhs_length (rule *r);
+
+/* Print this rule's RHS on OUT.  */
+void rule_rhs_print (rule *r, FILE *out);
+
+/* Print this rule on OUT.  */
+void rule_print (rule *r, FILE *out);
+
 
-  const char *guard;
-  short guard_line;
-} rule_t;
 
-extern struct rule_s *rules;
 
 /* Table of the symbols, indexed by the symbol number. */
-extern symbol_t **symbols;
+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.  */
-typedef short token_number_t;
-extern token_number_t *token_translations;
+extern symbol_number *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);
+
+/* Return the size of the longest rule RHS.  */
+size_t ritem_longest_rhs (void);
 
-extern int error_token_number;
+/* 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);
 
-/* Report the length of the RHS. */
-int rule_rhs_length PARAMS ((rule_t *rule));
+/* Print the grammar's rules on OUT.  */
+void grammar_rules_print (FILE *out);
 
-/* Dump RITEM for traces. */
-void ritem_print PARAMS ((FILE *out));
+/* Dump the grammar. */
+void grammar_dump (FILE *out, const char *title);
 
-/* Return the size of the longest rule RHS.  */
-size_t ritem_longest_rhs PARAMS ((void));
+/* 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_ */