* doc/bison.texinfo (Stack Overflow): xref to Recursion.

[bison.git] / src / gram.h

diff --git a/src/gram.h b/src/gram.h
index 087583ade78f0a759d2f53018812a39a98465f64..de782f7d646ef570f628230f767cb1d0ddbb8fa7 100644 (file)
--- a/src/gram.h
+++ b/src/gram.h
@@ -1,5 +1,5 @@
 /* Data definitions for internal representation of bison's input,
 /* Data definitions for internal representation of bison's input,

-   Copyright 1984, 1986, 1989, 1992, 2001, 2002
+   Copyright (C) 1984, 1986, 1989, 1992, 2001, 2002

    Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
    Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.


@@ -36,41 +36,48 @@
 
    The rules receive rule numbers 1 to NRULES in the order they are
    written.  More precisely Bison augments the grammar with the
 
    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
 
    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:
 
 
    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[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].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].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].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.
 
    The right hand side is stored as symbol numbers in a portion of
    RITEM.


@@ -80,11 +87,9 @@
    contains minus R, which identifies it as the end of a portion and
    says which rule it is for.
 
    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.
 
    Item numbers are used in the finite state machine to represent
    places that parsing can get to.


@@ -98,77 +103,154 @@
 
    Associativities are recorded similarly in SYMBOLS[I]->assoc.  */
 
 
    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 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) MIN_MAX)
+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 symbol_number_t start_symbol;

 
 

-extern int 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.  */
 
 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 number;
-
-  bucket *lhs;
-  short *rhs;
-  short prec;
-  short precsym;
-  associativity assoc;
-  short line;
+  rule_number_t user_number;
+
+  /* The index in RULES.  Usually the rule number in the source,
+     except if some rules are useless.  */
+  rule_number_t number;
+
+  symbol_t *lhs;
+  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;
+
+  location_t location;

   bool useful;
 
   const char *action;
   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;
 
 } rule_t;
 
 extern struct rule_s *rules;
 

-/* Table of the symbols, indexed by the symbol number. */
-extern struct bucket **symbols;
+/* 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));
+

 
 

-/* 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;
+
+/* Table of the symbols, indexed by the symbol number. */
+extern symbol_t **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_t *token_translations;

 extern int max_user_token_number;
 
 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;
 
 
 /* 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.  */
-
-extern int error_token_number;
-
-/* Report the length of the RHS. */
-int rule_rhs_length PARAMS ((rule_t *rule));
-

 /* Dump RITEM for traces. */
 void ritem_print PARAMS ((FILE *out));
 
 /* Return the size of the longest rule RHS.  */
 size_t ritem_longest_rhs PARAMS ((void));
 
 /* Dump RITEM for traces. */
 void ritem_print PARAMS ((FILE *out));
 
 /* Return the size of the longest rule RHS.  */
 size_t ritem_longest_rhs PARAMS ((void));
 

+/* 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,
+                                         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));
+

 #endif /* !GRAM_H_ */
 #endif /* !GRAM_H_ */