doc: one of the fixes for an ambiguous grammar was ambiguous too

[bison.git] / src / gram.h

diff --git a/src/gram.h b/src/gram.h
index 1aa5cd7d88b958d80301e326f46bf8e5f15f0fee..3f75dd8f951a9e3ed71397f65c2e181602c08d4e 100644 (file)
--- a/src/gram.h
+++ b/src/gram.h
@@ -1,23 +1,22 @@
-/* Data definitions for internal representation of bison's input,
-   Copyright (C) 1984, 1986, 1989, 1992, 2001, 2002
-   Free Software Foundation, Inc.
+/* Data definitions for internal representation of Bison's input.
+
+   Copyright (C) 1984, 1986, 1989, 1992, 2001-2007, 2009-2012 Free
+   Software Foundation, Inc.

 
    This file is part of Bison, the GNU Compiler Compiler.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 

-   Bison is free software; you can redistribute it and/or modify
+   This program is free software: you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by
    it under the terms of the GNU General Public License as published by

-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.

 
 

-   Bison is distributed in the hope that it will be useful,
+   This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License

-   along with Bison; see the file COPYING.  If not, write to
-   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-   Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

 
 #ifndef GRAM_H_
 # define GRAM_H_
 
 #ifndef GRAM_H_
 # define GRAM_H_


@@ -36,23 +35,23 @@
 
    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 are accessed via the rule number.
 
    The rules themselves are described by several arrays: amongst which
    RITEM, and RULES.
 
 
    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.
 
 
    RULES[R].lhs -- the symbol of the left hand side of rule R.
 


@@ -68,13 +67,15 @@
 
    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].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.
 
 
    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
    away by reduce).
 
    The right hand side is stored as symbol numbers in a portion of


@@ -104,123 +105,171 @@
 # include "location.h"
 # include "symtab.h"
 
 # 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 nsyms;
 extern int ntokens;
 extern int nvars;
 
 
 extern int nsyms;
 extern int ntokens;
 extern int nvars;
 

-typedef int item_number_t;
-# define ITEM_NUMBER_MAX ((item_number_t) INT_MAX)
-extern item_number_t *ritem;
+typedef int item_number;
+#define ITEM_NUMBER_MAX INT_MAX
+extern item_number *ritem;

 extern unsigned int nritems;
 
 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 are stored.
+/* 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, an symbol_number_t must be a valid item_number_t, and we
+   Therefore, a symbol_number must be a valid item_number, and we

    sometimes have to perform the converse transformation.  */
    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;
+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;
+}
+
+static inline bool
+item_number_is_symbol_number (item_number i)
+{
+  return i >= 0;
+}

 
 

-/* 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 item_number_of_rule_number(RNum) ((item_number_t) (- RNum))
-# define rule_number_of_item_number(INum) ((rule_number_t) (- INum))
+/* Rule numbers.  */
+typedef int rule_number;
+#define RULE_NUMBER_MAX INT_MAX
+extern rule_number nrules;

 
 

+static inline item_number
+rule_number_as_item_number (rule_number r)
+{
+  return -1 - r;
+}
+
+static inline rule_number
+item_number_as_rule_number (item_number i)
+{
+  return -1 - i;
+}
+
+static inline bool
+item_number_is_rule_number (item_number i)
+{
+  return i < 0;
+}

 
 /*--------.
 | Rules.  |
 `--------*/
 
 
 /*--------.
 | Rules.  |
 `--------*/
 

-typedef struct rule_s
+typedef struct

 {
   /* The number of the rule in the source.  It is usually the index in
      RULES too, except if there are useless rules.  */
 {
   /* The number of the rule in the source.  It is usually the index in
      RULES too, except if there are useless rules.  */

-  rule_number_t user_number;
+  rule_number user_number;

 
   /* The index in RULES.  Usually the rule number in the source,
      except if some rules are useless.  */
 
   /* The index in RULES.  Usually the rule number in the source,
      except if some rules are useless.  */

-  rule_number_t number;
+  rule_number number;

 
 

-  symbol_t *lhs;
-  item_number_t *rhs;
+  symbol *lhs;
+  item_number *rhs;

 
   /* This symbol provides both the associativity, and the precedence. */
 
   /* This symbol provides both the associativity, and the precedence. */

-  symbol_t *prec;
+  symbol *prec;

 
 

-  short dprec;
-  short merger;
+  int dprec;
+  int merger;

 
   /* This symbol was attached to the rule via %prec. */
 
   /* This symbol was attached to the rule via %prec. */

-  symbol_t *precsym;
+  symbol *precsym;

 
 

-  location_t location;
+  location location;

   bool useful;
 
   const char *action;
   bool useful;
 
   const char *action;

-  location_t action_location;
-} rule_t;
+  location action_location;
+} rule;

 
 

-extern struct rule_s *rules;
+extern rule *rules;

 
 

-/* Table of the symbols, indexed by the symbol number. */
-extern symbol_t **symbols;
+/* A function that selects a rule.  */
+typedef bool (*rule_filter) (rule *);

 
 

-/* 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;
+/* Return true IFF the rule has a `number' smaller than NRULES.  That is, it is
+   useful in the grammar.  */
+bool rule_useful_in_grammar_p (rule *r);
+
+/* Return true IFF the rule has a `number' higher than NRULES.  That is, it is
+   useless in the grammar.  */
+bool rule_useless_in_grammar_p (rule *r);

 
 

+/* Return true IFF the rule is not flagged as useful but is useful in the
+   grammar.  In other words, it was discarded because of conflicts.  */
+bool rule_useless_in_parser_p (rule *r);

 
 

-/* 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. */
+/* 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);
+void rule_lhs_print_xml (rule *r, FILE *out, int level);

 
 

-extern int glr_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);

 
 

-/* 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 **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. */
 
 /* Dump RITEM for traces. */

-void ritem_print PARAMS ((FILE *out));
+void ritem_print (FILE *out);

 
 /* Return the size of the longest rule RHS.  */
 
 /* 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 PARAMS ((FILE *out, const char *title,
-                                         rule_number_t begin,
-                                         rule_number_t end));
+/* Print the grammar's rules that match FILTER 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 PARAMS ((FILE *out));
+/* Print the grammar's useful rules on OUT.  */
+void grammar_rules_print (FILE *out);
+/* Print all of the grammar's rules with a "usefulness" attribute.  */
+void grammar_rules_print_xml (FILE *out, int level);

 
 /* Dump the grammar. */
 
 /* Dump the grammar. */

-void grammar_dump PARAMS ((FILE *out, const char *title));
+void grammar_dump (FILE *out, const char *title);
+
+/* Report on STDERR the rules that are not flagged USEFUL, using the
+   MESSAGE (which can be `rule useless in grammar' when invoked after grammar
+   reduction, or `rule useless in parser due to conflicts' after conflicts
+   were taken into account).  */
+void grammar_rules_useless_report (const char *message);

 
 /* Free the packed grammar. */
 
 /* Free the packed grammar. */

-void grammar_free PARAMS ((void));
+void grammar_free (void);

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