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

[bison.git] / src / reader.c

diff --git a/src/reader.c b/src/reader.c
index 0a3f0e256c1cac741e17bcbbd75d924b0f48d83a..d7527158aca5549dc388a416dad300191056f371 100644 (file)
--- a/src/reader.c
+++ b/src/reader.c
@@ -27,7 +27,6 @@
 #include "files.h"
 #include "symtab.h"
 #include "symlist.h"
 #include "files.h"
 #include "symtab.h"
 #include "symlist.h"

-#include "options.h"

 #include "gram.h"
 #include "complain.h"
 #include "output.h"
 #include "gram.h"
 #include "complain.h"
 #include "output.h"


@@ -35,9 +34,9 @@
 #include "conflicts.h"
 #include "muscle_tab.h"
 
 #include "conflicts.h"
 #include "muscle_tab.h"
 

-int lineno;

 static symbol_list_t *grammar = NULL;
 static int start_flag = 0;
 static symbol_list_t *grammar = NULL;
 static int start_flag = 0;

+merger_list *merge_functions;

 
 /* Nonzero if %union has been seen.  */
 int typed = 0;
 
 /* Nonzero if %union has been seen.  */
 int typed = 0;


@@ -50,7 +49,7 @@ void
 grammar_start_symbol_set (symbol_t *s, location_t l)
 {
   if (start_flag)
 grammar_start_symbol_set (symbol_t *s, location_t l)
 {
   if (start_flag)

-    complain (_("multiple %s declarations"), "%start");
+    complain_at (l, _("multiple %s declarations"), "%start");

   else
     {
       start_flag = 1;
   else
     {
       start_flag = 1;


@@ -106,29 +105,66 @@ epilogue_set (const char *epilogue, location_t location)
 
 \f
 
 
 \f
 

-/*-------------------------------------------------------------------.
-| Generate a dummy symbol, a nonterminal, whose name cannot conflict |
-| with the user's names.                                             |
+ /*-------------------------------------------------------------------.
+| Return the merger index for a merging function named NAME, whose   |
+| arguments have type TYPE.  Records the function, if new, in        |
+| merger_list.                                                      |

 `-------------------------------------------------------------------*/
 
 `-------------------------------------------------------------------*/
 

-static symbol_t *
-gensym (location_t location)
+static int
+get_merge_function (const char* name, const char* type,
+                   location_t loc)

 {
 {

-  /* Incremented for each generated symbol */
-  static int gensym_count = 0;
-  static char buf[256];
+  merger_list *syms;
+  merger_list head;
+  int n;
+
+  if (! glr_parser)
+    return 0;

 
 

-  symbol_t *sym;
+  if (type == NULL)
+    type = "";

 
 

-  sprintf (buf, "@%d", ++gensym_count);
-  sym = getsym (buf, location);
-  sym->class = nterm_sym;
-  sym->number = nvars++;
-  return sym;
+  head.next = merge_functions;
+  for (syms = &head, n = 1; syms->next != NULL; syms = syms->next, n += 1)
+    if (strcmp (name, syms->next->name) == 0)
+      break;
+  if (syms->next == NULL)
+    {
+      syms->next = XMALLOC (merger_list, 1);
+      syms->next->name = xstrdup (name);
+      syms->next->type = xstrdup (type);
+      syms->next->next = NULL;
+      merge_functions = head.next;
+    }
+  else if (strcmp (type, syms->next->type) != 0)
+    warn_at (loc, _("result type clash on merge function %s: `%s' vs. `%s'"),
+            name, type, syms->next->type);
+  return n;

 }
 }

+
+/*--------------------------------------.
+| Free all merge-function definitions. |
+`--------------------------------------*/
+
+void
+free_merger_functions (void)
+{
+  merger_list *L0;
+  if (! glr_parser)
+    return;
+  L0 = merge_functions;
+  while (L0 != NULL)
+    {
+      merger_list *L1 = L0->next;
+      free (L0);
+      L0 = L1;
+    }
+}
+

 \f
 /*-------------------------------------------------------------------.
 \f
 /*-------------------------------------------------------------------.

-| Parse the input grammar into a one symbol_list_t structure.  Each    |
+| Parse the input grammar into a one symbol_list_t structure.  Each  |

 | rule is represented by a sequence of symbols: the left hand side   |
 | followed by the contents of the right hand side, followed by a     |
 | null pointer instead of a symbol to terminate the rule.  The next  |
 | rule is represented by a sequence of symbols: the left hand side   |
 | followed by the contents of the right hand side, followed by a     |
 | null pointer instead of a symbol to terminate the rule.  The next  |


@@ -200,7 +236,7 @@ grammar_rule_begin (symbol_t *lhs, location_t location)
       ++nvars;
     }
   else if (lhs->class == token_sym)
       ++nvars;
     }
   else if (lhs->class == token_sym)

-    complain (_("rule given for %s, which is a token"), lhs->tag);
+    complain_at (location, _("rule given for %s, which is a token"), lhs->tag);

 }
 
 /* Check that the last rule (CURRENT_RULE) is properly defined.  For
 }
 
 /* Check that the last rule (CURRENT_RULE) is properly defined.  For


@@ -224,14 +260,16 @@ grammar_current_rule_check (void)
       const char *lhs_type = lhs->type_name       ? lhs->type_name       : "";
       const char *rhs_type = first_rhs->type_name ? first_rhs->type_name : "";
       if (strcmp (lhs_type, rhs_type))
       const char *lhs_type = lhs->type_name       ? lhs->type_name       : "";
       const char *rhs_type = first_rhs->type_name ? first_rhs->type_name : "";
       if (strcmp (lhs_type, rhs_type))

-       complain (_("type clash (`%s' `%s') on default action"),
-                 lhs_type, rhs_type);
+       complain_at (current_rule->location,
+                    _("type clash (`%s' `%s') on default action"),
+                    lhs_type, rhs_type);

     }
   /* Warn if there is no default for $$ but we need one.  */
   else
     {
       if (lhs->type_name)
     }
   /* Warn if there is no default for $$ but we need one.  */
   else
     {
       if (lhs->type_name)

-       complain (_("empty rule for typed nonterminal, and no action"));
+       complain_at (current_rule->location,
+                    _("empty rule for typed nonterminal, and no action"));

     }
 }
 
     }
 }
 


@@ -267,7 +305,7 @@ grammar_midrule_action (void)
   /* Make a DUMMY nonterminal, whose location is that of the midrule
      action.  Create the MIDRULE.  */
   location_t dummy_location = current_rule->action_location;
   /* Make a DUMMY nonterminal, whose location is that of the midrule
      action.  Create the MIDRULE.  */
   location_t dummy_location = current_rule->action_location;

-  symbol_t *dummy = gensym (dummy_location);
+  symbol_t *dummy = dummy_symbol_get (dummy_location);

   symbol_list_t *midrule = symbol_list_new (dummy, dummy_location);
 
   /* Make a new rule, whose body is empty, before the current one, so
   symbol_list_t *midrule = symbol_list_new (dummy, dummy_location);
 
   /* Make a new rule, whose body is empty, before the current one, so


@@ -299,13 +337,41 @@ grammar_midrule_action (void)
 /* Set the precedence symbol of the current rule to PRECSYM. */
 
 void
 /* Set the precedence symbol of the current rule to PRECSYM. */
 
 void

-grammar_current_rule_prec_set (symbol_t *precsym)
+grammar_current_rule_prec_set (symbol_t *precsym, location_t location)

 {
   if (current_rule->ruleprec)
 {
   if (current_rule->ruleprec)

-    complain (_("two @prec's in a row"));
+    complain_at (location, _("two @prec's in a row"));

   current_rule->ruleprec = precsym;
 }
 
   current_rule->ruleprec = precsym;
 }
 

+/* Attach dynamic precedence DPREC to the current rule. */
+
+void
+grammar_current_rule_dprec_set (int dprec, location_t location)
+{
+  if (! glr_parser)
+    warn_at (location, _("%%dprec affects only GLR parsers"));
+  if (dprec <= 0)
+    complain_at (location, _("%%dprec must be followed by positive number"));
+  else if (current_rule->dprec != 0)
+    complain_at (location, _("only one %%dprec allowed per rule"));
+  current_rule->dprec = dprec;
+}
+
+/* Attach a merge function NAME with argument type TYPE to current
+   rule. */
+
+void
+grammar_current_rule_merge_set (const char* name, location_t location)
+{
+  if (! glr_parser)
+    warn_at (location, _("%%merge affects only GLR parsers"));
+  if (current_rule->merger != 0)
+    complain_at (location, _("only one %%merge allowed per rule"));
+  current_rule->merger =
+    get_merge_function (name, current_rule->sym->type_name, location);
+}
+

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


@@ -318,7 +384,6 @@ grammar_current_rule_symbol_append (symbol_t *symbol, location_t location)
   grammar_symbol_append (symbol, location);
 }
 
   grammar_symbol_append (symbol, location);
 }
 

-

 /* 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.  If needed, move the previous
    action as a mid-rule action.  */
 


@@ -340,17 +405,13 @@ grammar_current_rule_action_append (const char *action, location_t location)
 static void
 packgram (void)
 {
 static void
 packgram (void)
 {

-  unsigned int itemno;
-  int ruleno;
-  symbol_list_t *p;
+  unsigned int itemno = 0;
+  rule_number_t ruleno = 0;
+  symbol_list_t *p = grammar;

 
   ritem = XCALLOC (item_number_t, nritems);
 
   ritem = XCALLOC (item_number_t, nritems);

-  rules = XCALLOC (rule_t, nrules) - 1;
-
-  itemno = 0;
-  ruleno = 1;
+  rules = XCALLOC (rule_t, nrules);

 
 

-  p = grammar;

   while (p)
     {
       symbol_t *ruleprec = p->ruleprec;
   while (p)
     {
       symbol_t *ruleprec = p->ruleprec;


@@ -362,6 +423,8 @@ packgram (void)
       rules[ruleno].useful = TRUE;
       rules[ruleno].action = p->action;
       rules[ruleno].action_location = p->action_location;
       rules[ruleno].useful = TRUE;
       rules[ruleno].action = p->action;
       rules[ruleno].action_location = p->action_location;

+      rules[ruleno].dprec = p->dprec;
+      rules[ruleno].merger = p->merger;

 
       p = p->next;
       while (p && p->sym)
 
       p = p->next;
       while (p && p->sym)


@@ -384,7 +447,7 @@ packgram (void)
          rules[ruleno].precsym = ruleprec;
          rules[ruleno].prec = ruleprec;
        }
          rules[ruleno].precsym = ruleprec;
          rules[ruleno].prec = ruleprec;
        }

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

       ++ruleno;
 
       if (p)
       ++ruleno;
 
       if (p)


@@ -393,7 +456,7 @@ packgram (void)
 
   assert (itemno == nritems);
 
 
   assert (itemno == nritems);
 

-  if (trace_flag)
+  if (trace_flag & trace_sets)

     ritem_print (stderr);
 }
 \f
     ritem_print (stderr);
 }
 \f


@@ -408,24 +471,23 @@ void
 reader (void)
 {
   gram_control_t gram_control;
 reader (void)
 {
   gram_control_t gram_control;

-  lineno = 1;

 
   /* Initialize the symbol table.  */
   symbols_new ();
 
 
   /* Initialize the symbol table.  */
   symbols_new ();
 

-  /* Construct the axiom symbol. */
-  axiom = getsym ("$axiom", empty_location);
-  axiom->class = nterm_sym;
-  axiom->number = nvars++;
+  /* Construct the accept symbol. */
+  accept = symbol_get ("$accept", empty_location);
+  accept->class = nterm_sym;
+  accept->number = nvars++;

 
   /* Construct the error token */
 
   /* Construct the error token */

-  errtoken = getsym ("error", empty_location);
+  errtoken = symbol_get ("error", empty_location);

   errtoken->class = token_sym;
   errtoken->number = ntokens++;
 
   /* Construct a token that represents all undefined literal tokens.
      It is always token number 2.  */
   errtoken->class = token_sym;
   errtoken->number = ntokens++;
 
   /* Construct a token that represents all undefined literal tokens.
      It is always token number 2.  */

-  undeftoken = getsym ("$undefined.", empty_location);
+  undeftoken = symbol_get ("$undefined", empty_location);

   undeftoken->class = token_sym;
   undeftoken->number = ntokens++;
 
   undeftoken->class = token_sym;
   undeftoken->number = ntokens++;
 


@@ -441,6 +503,11 @@ reader (void)
   scanner_initialize ();
   gram_parse (&gram_control);
 
   scanner_initialize ();
   gram_parse (&gram_control);
 

+  /* If something went wrong during the parsing, don't try to
+     continue.  */
+  if (complain_message_count)
+    exit (1);
+

   /* Grammar has been read.  Do some checking */
   if (nrules == 0)
     fatal (_("no rules in the input grammar"));
   /* Grammar has been read.  Do some checking */
   if (nrules == 0)
     fatal (_("no rules in the input grammar"));


@@ -448,25 +515,25 @@ reader (void)
   /* Report any undefined symbols and consider them nonterminals.  */
   symbols_check_defined ();
 
   /* Report any undefined symbols and consider them nonterminals.  */
   symbols_check_defined ();
 

-  /* If the user did not define her EOFTOKEN, do it now. */
-  if (!eoftoken)
+  /* If the user did not define her ENDTOKEN, do it now. */
+  if (!endtoken)

     {
     {

-      eoftoken = getsym ("$", empty_location);
-      eoftoken->class = token_sym;
-      eoftoken->number = 0;
+      endtoken = symbol_get ("$end", empty_location);
+      endtoken->class = token_sym;
+      endtoken->number = 0;

       /* Value specified by POSIX.  */
       /* Value specified by POSIX.  */

-      eoftoken->user_token_number = 0;
+      endtoken->user_token_number = 0;

     }
 
   /* Insert the initial rule, which line is that of the first rule
      (not that of the start symbol):
 
     }
 
   /* Insert the initial rule, which line is that of the first rule
      (not that of the start symbol):
 

-     axiom: %start EOF.  */
+     accept: %start EOF.  */

   {
   {

-    symbol_list_t *p = symbol_list_new (axiom, empty_location);
+    symbol_list_t *p = symbol_list_new (accept, empty_location);

     p->location = grammar->location;
     p->next = symbol_list_new (startsymbol, empty_location);
     p->location = grammar->location;
     p->next = symbol_list_new (startsymbol, empty_location);

-    p->next->next = symbol_list_new (eoftoken, empty_location);
+    p->next->next = symbol_list_new (endtoken, empty_location);

     p->next->next->next = symbol_list_new (NULL, empty_location);
     p->next->next->next->next = grammar;
     nrules += 1;
     p->next->next->next = symbol_list_new (NULL, empty_location);
     p->next->next->next->next = grammar;
     nrules += 1;