Clean up handling of %destructor for the end token (token 0).

[bison.git] / src / reader.c

diff --git a/src/reader.c b/src/reader.c
index 0e0a8c21bebecb0588e8b20fdd628f00f0ea7452..928be1b85e89d1e5f4c6e16c77336a28bcc68293 100644 (file)
--- a/src/reader.c
+++ b/src/reader.c
@@ -1,7 +1,7 @@
 /* Input parser for Bison
 
    Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000, 2001, 2002, 2003,
 /* Input parser for Bison
 
    Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000, 2001, 2002, 2003,

-   2005 Free Software Foundation, Inc.
+   2005, 2006 Free Software Foundation, Inc.

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


@@ -22,6 +22,7 @@
 
 #include <config.h>
 #include "system.h"
 
 #include <config.h>
 #include "system.h"

+#include <assert.h>

 
 #include <quotearg.h>
 
 
 #include <quotearg.h>
 


@@ -31,17 +32,23 @@
 #include "getargs.h"
 #include "gram.h"
 #include "muscle_tab.h"
 #include "getargs.h"
 #include "gram.h"
 #include "muscle_tab.h"

-#include "output.h"

 #include "reader.h"
 #include "symlist.h"
 #include "symtab.h"
 #include "reader.h"
 #include "symlist.h"
 #include "symtab.h"

+#include "scan-gram.h"
+#include "scan-code.h"
+
+static void check_and_convert_grammar (void);

 
 static symbol_list *grammar = NULL;
 static bool start_flag = false;
 merger_list *merge_functions;
 
 /* Was %union seen?  */
 
 static symbol_list *grammar = NULL;
 static bool start_flag = false;
 merger_list *merge_functions;
 
 /* Was %union seen?  */

-bool typed = false;
+bool union_seen = false;
+
+/* Was a tag seen?  */
+bool tag_seen = false;

 
 /* Should rules have a default precedence?  */
 bool default_prec = true;
 
 /* Should rules have a default precedence?  */
 bool default_prec = true;


@@ -64,18 +71,20 @@ grammar_start_symbol_set (symbol *sym, location loc)
 }
 
 
 }
 
 

-/*----------------------------------------------------------------.
-| There are two prologues: one before %union, one after.  Augment |
-| the current one.                                                |
-`----------------------------------------------------------------*/
+/*---------------------------------------------------------------------.
+| There are two prologues: one before the first %union and one after.  |
+|  Augment the one specified by POST.                                  |
+`---------------------------------------------------------------------*/

 
 void
 
 void

-prologue_augment (const char *prologue, location loc)
+prologue_augment (const char *prologue, location loc, bool post)

 {
   struct obstack *oout =
 {
   struct obstack *oout =

-    !typed ? &pre_prologue_obstack : &post_prologue_obstack;
+    !post ? &pre_prologue_obstack : &post_prologue_obstack;

 
   obstack_fgrow1 (oout, "]b4_syncline(%d, [[", loc.start.line);
 
   obstack_fgrow1 (oout, "]b4_syncline(%d, [[", loc.start.line);

+  /* FIXME: Protection of M4 characters missing here.  See
+     output.c:escaped_output.  */

   MUSCLE_OBSTACK_SGROW (oout,
                        quotearg_style (c_quoting_style, loc.start.file));
   obstack_sgrow (oout, "]])[\n");
   MUSCLE_OBSTACK_SGROW (oout,
                        quotearg_style (c_quoting_style, loc.start.file));
   obstack_sgrow (oout, "]])[\n");


@@ -84,14 +93,13 @@ prologue_augment (const char *prologue, location loc)
 
 \f
 
 
 \f
 

-/*-------------------------------------------------------------------.
-| Return the merger index for a merging function named NAME, whose   |
-| arguments have type TYPE.  Records the function, if new, in        |
-| MERGER_LIST.                                                      |
-`-------------------------------------------------------------------*/
+/*------------------------------------------------------------------------.
+| Return the merger index for a merging function named NAME.  Records the |
+| function, if new, in MERGER_LIST.                                       |
+`------------------------------------------------------------------------*/

 
 static int
 
 static int

-get_merge_function (uniqstr name, uniqstr type, location loc)
+get_merge_function (uniqstr name)

 {
   merger_list *syms;
   merger_list head;
 {
   merger_list *syms;
   merger_list head;


@@ -100,9 +108,6 @@ get_merge_function (uniqstr name, uniqstr type, location loc)
   if (! glr_parser)
     return 0;
 
   if (! glr_parser)
     return 0;
 

-  if (type == NULL)
-    type = uniqstr_new ("");
-

   head.next = merge_functions;
   for (syms = &head, n = 1; syms->next; syms = syms->next, n += 1)
     if (UNIQSTR_EQ (name, syms->next->name))
   head.next = merge_functions;
   for (syms = &head, n = 1; syms->next; syms = syms->next, n += 1)
     if (UNIQSTR_EQ (name, syms->next->name))


@@ -111,16 +116,51 @@ get_merge_function (uniqstr name, uniqstr type, location loc)
     {
       syms->next = xmalloc (sizeof syms->next[0]);
       syms->next->name = uniqstr_new (name);
     {
       syms->next = xmalloc (sizeof syms->next[0]);
       syms->next->name = uniqstr_new (name);

-      syms->next->type = uniqstr_new (type);
+      /* After all symbol type declarations have been parsed, packgram invokes
+        record_merge_function_type to set the type.  */
+      syms->next->type = NULL;

       syms->next->next = NULL;
       merge_functions = head.next;
     }
       syms->next->next = NULL;
       merge_functions = head.next;
     }

-  else if (!UNIQSTR_EQ (type, syms->next->type))
-    warn_at (loc, _("result type clash on merge function %s: <%s> != <%s>"),
-            name, type, syms->next->type);

   return n;
 }
 
   return n;
 }
 

+/*-------------------------------------------------------------------------.
+| For the existing merging function with index MERGER, record the result   |
+| type as TYPE as required by the lhs of the rule whose %merge declaration |
+| is at DECLARATION_LOC.                                                   |
+`-------------------------------------------------------------------------*/
+
+static void
+record_merge_function_type (int merger, uniqstr type, location declaration_loc)
+{
+  int merger_find;
+  merger_list *merge_function;
+
+  if (merger <= 0)
+    return;
+
+  if (type == NULL)
+    type = uniqstr_new ("");
+
+  merger_find = 1;
+  for (merge_function = merge_functions;
+       merge_function != NULL && merger_find != merger;
+       merge_function = merge_function->next)
+    merger_find += 1;
+  assert (merge_function != NULL && merger_find == merger);
+  if (merge_function->type != NULL && !UNIQSTR_EQ (merge_function->type, type))
+    {
+      complain_at (declaration_loc,
+                  _("result type clash on merge function `%s': <%s> != <%s>"),
+                  merge_function->name, type, merge_function->type);
+      complain_at (merge_function->type_declaration_location,
+                  _("previous declaration"));
+    }
+  merge_function->type = uniqstr_new (type);
+  merge_function->type_declaration_location = declaration_loc;
+}
+

 /*--------------------------------------.
 | Free all merge-function definitions. |
 `--------------------------------------*/
 /*--------------------------------------.
 | Free all merge-function definitions. |
 `--------------------------------------*/


@@ -174,7 +214,7 @@ grammar_symbol_append (symbol *sym, location loc)
 /* The rule currently being defined, and the previous rule.
    CURRENT_RULE points to the first LHS of the current rule, while
    PREVIOUS_RULE_END points to the *end* of the previous rule (NULL).  */
 /* The rule currently being defined, and the previous rule.
    CURRENT_RULE points to the first LHS of the current rule, while
    PREVIOUS_RULE_END points to the *end* of the previous rule (NULL).  */

-symbol_list *current_rule = NULL;
+static symbol_list *current_rule = NULL;

 static symbol_list *previous_rule_end = NULL;
 
 
 static symbol_list *previous_rule_end = NULL;
 
 


@@ -210,6 +250,19 @@ grammar_current_rule_begin (symbol *lhs, location loc)
 }
 
 
 }
 
 

+/*----------------------------------------------------------------------.
+| A symbol should be used if it has a destructor, or if it is a         |
+| mid-rule symbol (i.e., the generated LHS replacing a mid-rule         |
+| action) that was assigned to, as in "exp: { $$ = 1; } { $$ = $1; }".  |
+`----------------------------------------------------------------------*/
+
+static bool
+symbol_should_be_used (symbol_list const *s)
+{
+  return (s->sym->destructor
+         || (s->midrule && s->midrule->used));
+}
+

 /*----------------------------------------------------------------.
 | Check that the rule R is properly defined.  For instance, there |
 | should be no type clash on the default action.                  |
 /*----------------------------------------------------------------.
 | Check that the rule R is properly defined.  For instance, there |
 | should be no type clash on the default action.                  |


@@ -245,13 +298,13 @@ grammar_rule_check (const symbol_list *r)
                 _("empty rule for typed nonterminal, and no action"));
     }
 
                 _("empty rule for typed nonterminal, and no action"));
     }
 

-  /* Check that typed symbol values are used.  */
+  /* Check that symbol values that should be used are in fact used.  */

   {
     symbol_list const *l = r;
     int n = 0;
     for (; l && l->sym; l = l->next, ++n)
       if (! (l->used
   {
     symbol_list const *l = r;
     int n = 0;
     for (; l && l->sym; l = l->next, ++n)
       if (! (l->used

-            || !l->sym->type_name
+            || !symbol_should_be_used (l)

             /* The default action, $$ = $1, `uses' both.  */
             || (!r->action && (n == 0 || n == 1))))
        {
             /* The default action, $$ = $1, `uses' both.  */
             || (!r->action && (n == 0 || n == 1))))
        {


@@ -274,7 +327,6 @@ grammar_current_rule_end (location loc)
   /* Put an empty link in the list to mark the end of this rule  */
   grammar_symbol_append (NULL, grammar_end->location);
   current_rule->location = loc;
   /* Put an empty link in the list to mark the end of this rule  */
   grammar_symbol_append (NULL, grammar_end->location);
   current_rule->location = loc;

-  grammar_rule_check (current_rule);

 }
 
 
 }
 
 


@@ -285,7 +337,7 @@ grammar_current_rule_end (location loc)
 | rule.                                                              |
 `-------------------------------------------------------------------*/
 
 | rule.                                                              |
 `-------------------------------------------------------------------*/
 

-static void
+void

 grammar_midrule_action (void)
 {
   /* Since the action was written out with this rule's number, we must
 grammar_midrule_action (void)
 {
   /* Since the action was written out with this rule's number, we must


@@ -307,6 +359,9 @@ grammar_midrule_action (void)
   midrule->action = current_rule->action;
   midrule->action_location = dummy_location;
   current_rule->action = NULL;
   midrule->action = current_rule->action;
   midrule->action_location = dummy_location;
   current_rule->action = NULL;

+  /* The action has not been translated yet, so $$ use hasn't been
+     detected yet.  */
+  midrule->used = false;

 
   if (previous_rule_end)
     previous_rule_end->next = midrule;
 
   if (previous_rule_end)
     previous_rule_end->next = midrule;


@@ -314,14 +369,17 @@ grammar_midrule_action (void)
     grammar = midrule;
 
   /* End the dummy's rule.  */
     grammar = midrule;
 
   /* End the dummy's rule.  */

-  previous_rule_end = symbol_list_new (NULL, dummy_location);
-  previous_rule_end->next = current_rule;
+  midrule->next = symbol_list_new (NULL, dummy_location);
+  midrule->next->next = current_rule;

 
 

-  midrule->next = previous_rule_end;
+  previous_rule_end = midrule->next;

 
   /* Insert the dummy nonterminal replacing the midrule action into
 
   /* Insert the dummy nonterminal replacing the midrule action into

-     the current rule.  */
+     the current rule.  Bind it to its dedicated rule.  */

   grammar_current_rule_symbol_append (dummy, dummy_location);
   grammar_current_rule_symbol_append (dummy, dummy_location);

+  grammar_end->midrule = midrule;
+  midrule->midrule_parent_rule = current_rule;
+  midrule->midrule_parent_rhs_index = symbol_list_length (current_rule->next);

 }
 
 /* Set the precedence symbol of the current rule to PRECSYM. */
 }
 
 /* Set the precedence symbol of the current rule to PRECSYM. */


@@ -358,8 +416,8 @@ grammar_current_rule_merge_set (uniqstr name, location loc)
     warn_at (loc, _("%s affects only GLR parsers"), "%merge");
   if (current_rule->merger != 0)
     complain_at (loc, _("only one %s allowed per rule"), "%merge");
     warn_at (loc, _("%s affects only GLR parsers"), "%merge");
   if (current_rule->merger != 0)
     complain_at (loc, _("only one %s allowed per rule"), "%merge");

-  current_rule->merger =
-    get_merge_function (name, current_rule->sym->type_name, loc);
+  current_rule->merger = get_merge_function (name);
+  current_rule->merger_declaration_location = loc;

 }
 
 /* Attach SYM to the current rule.  If needed, move the previous
 }
 
 /* Attach SYM to the current rule.  If needed, move the previous


@@ -373,14 +431,15 @@ grammar_current_rule_symbol_append (symbol *sym, location loc)
   grammar_symbol_append (sym, loc);
 }
 
   grammar_symbol_append (sym, loc);
 }
 

-/* Attach an ACTION to the current rule.  If needed, move the previous
-   action as a mid-rule action.  */
+/* Attach an ACTION to the current rule.  */

 
 void
 grammar_current_rule_action_append (const char *action, location loc)
 {
   if (current_rule->action)
     grammar_midrule_action ();
 
 void
 grammar_current_rule_action_append (const char *action, location loc)
 {
   if (current_rule->action)
     grammar_midrule_action ();

+  /* After all symbol declarations have been parsed, packgram invokes
+     translate_rule_action.  */

   current_rule->action = action;
   current_rule->action_location = loc;
 }
   current_rule->action = action;
   current_rule->action_location = loc;
 }


@@ -398,12 +457,19 @@ packgram (void)
   rule_number ruleno = 0;
   symbol_list *p = grammar;
 
   rule_number ruleno = 0;
   symbol_list *p = grammar;
 

-  ritem = xnmalloc (nritems, sizeof *ritem);
+  ritem = xnmalloc (nritems + 1, sizeof *ritem);
+
+  /* This sentinel is used by build_relations in gram.c.  */
+  *ritem++ = 0;
+

   rules = xnmalloc (nrules, sizeof *rules);
 
   while (p)
     {
   rules = xnmalloc (nrules, sizeof *rules);
 
   while (p)
     {

+      int rule_length = 0;

       symbol *ruleprec = p->ruleprec;
       symbol *ruleprec = p->ruleprec;

+      record_merge_function_type (p->merger, p->sym->type_name,
+                                 p->merger_declaration_location);

       rules[ruleno].user_number = ruleno;
       rules[ruleno].number = ruleno;
       rules[ruleno].lhs = p->sym;
       rules[ruleno].user_number = ruleno;
       rules[ruleno].number = ruleno;
       rules[ruleno].lhs = p->sym;


@@ -414,21 +480,36 @@ packgram (void)
       rules[ruleno].precsym = NULL;
       rules[ruleno].location = p->location;
       rules[ruleno].useful = true;
       rules[ruleno].precsym = NULL;
       rules[ruleno].location = p->location;
       rules[ruleno].useful = true;

-      rules[ruleno].action = p->action;
+      rules[ruleno].action = p->action ? translate_rule_action (p) : NULL;

       rules[ruleno].action_location = p->action_location;
 
       rules[ruleno].action_location = p->action_location;
 

-      p = p->next;
-      while (p && p->sym)
+      /* If this rule contains midrules, rest assured that
+        grammar_midrule_action inserted the midrules into grammar before this
+        rule.  Thus, the midrule actions have already been scanned in order to
+        set `used' flags for this rule's rhs, so grammar_rule_check will work
+        properly.  */
+      /* Don't check the generated rule 0.  It has no action, so some rhs
+        symbols may appear unused, but the parsing algorithm ensures that
+        %destructor's are invoked appropriately.  */
+      if (p != grammar)
+       grammar_rule_check (p);
+
+      for (p = p->next; p && p->sym; p = p->next)

        {
        {

+         ++rule_length;
+
+         /* Don't allow rule_length == INT_MAX, since that might
+            cause confusion with strtol if INT_MAX == LONG_MAX.  */
+         if (rule_length == INT_MAX)
+             fatal_at (rules[ruleno].location, _("rule is too long"));
+

          /* item_number = symbol_number.
             But the former needs to contain more: negative rule numbers. */
          ritem[itemno++] = symbol_number_as_item_number (p->sym->number);
          /* A rule gets by default the precedence and associativity
          /* item_number = symbol_number.
             But the former needs to contain more: negative rule numbers. */
          ritem[itemno++] = symbol_number_as_item_number (p->sym->number);
          /* A rule gets by default the precedence and associativity

-            of the last token in it.  */
+            of its last token.  */

          if (p->sym->class == token_sym && default_prec)
            rules[ruleno].prec = p->sym;
          if (p->sym->class == token_sym && default_prec)
            rules[ruleno].prec = p->sym;

-         if (p)
-           p = p->next;

        }
 
       /* If this rule has a %prec,
        }
 
       /* If this rule has a %prec,


@@ -438,15 +519,17 @@ packgram (void)
          rules[ruleno].precsym = ruleprec;
          rules[ruleno].prec = ruleprec;
        }
          rules[ruleno].precsym = ruleprec;
          rules[ruleno].prec = ruleprec;
        }

+      /* An item ends by the rule number (negated).  */

       ritem[itemno++] = rule_number_as_item_number (ruleno);
       ritem[itemno++] = rule_number_as_item_number (ruleno);

+      assert (itemno < ITEM_NUMBER_MAX);

       ++ruleno;
       ++ruleno;

+      assert (ruleno < RULE_NUMBER_MAX);

 
       if (p)
        p = p->next;
     }
 
 
       if (p)
        p = p->next;
     }
 

-  if (itemno != nritems)
-    abort ();
+  assert (itemno == nritems);

 
   if (trace_flag & trace_sets)
     ritem_print (stderr);
 
   if (trace_flag & trace_sets)
     ritem_print (stderr);


@@ -489,15 +572,25 @@ reader (void)
 
   gram__flex_debug = trace_flag & trace_scan;
   gram_debug = trace_flag & trace_parse;
 
   gram__flex_debug = trace_flag & trace_scan;
   gram_debug = trace_flag & trace_parse;

-  scanner_initialize ();
+  gram_scanner_initialize ();

   gram_parse ();
 
   gram_parse ();
 

-  /* If something went wrong during the parsing, don't try to
-     continue.  */
-  if (complaint_issued)
-    return;
+  if (! complaint_issued)
+    check_and_convert_grammar ();
+
+  xfclose (gram_in);
+}
+

 
 

-  /* Grammar has been read.  Do some checking */
+/*-------------------------------------------------------------.
+| Check the grammar that has just been read, and convert it to |
+| internal form.                                              |
+`-------------------------------------------------------------*/
+
+static void
+check_and_convert_grammar (void)
+{
+  /* Grammar has been read.  Do some checking.  */

   if (nrules == 0)
     fatal (_("no rules in the input grammar"));
 
   if (nrules == 0)
     fatal (_("no rules in the input grammar"));
 


@@ -514,7 +607,7 @@ reader (void)
       endtoken->user_token_number = 0;
     }
 
       endtoken->user_token_number = 0;
     }
 

-  /* Insert the initial rule, which line is that of the first rule
+  /* Insert the initial rule, whose line is that of the first rule

      (not that of the start symbol):
 
      accept: %start EOF.  */
      (not that of the start symbol):
 
      accept: %start EOF.  */


@@ -530,10 +623,7 @@ reader (void)
     grammar = p;
   }
 
     grammar = p;
   }
 

-  if (! (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars))
-    abort ();
-
-  xfclose (gram_in);
+  assert (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars);

 
   /* Assign the symbols their symbol numbers.  Write #defines for the
      token symbols into FDEFINES if requested.  */
 
   /* Assign the symbols their symbol numbers.  Write #defines for the
      token symbols into FDEFINES if requested.  */