Added GPLv2+ as license for libgrammatic

[cascardo/grammar.git] / first.c

diff --git a/first.c b/first.c
index e79d98d..f90cdcf 100644 (file)
--- a/first.c
+++ b/first.c
@@ -1,3 +1,23 @@
+/*
+ *  Copyright (C) 2005  Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
+ *
+ *  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
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  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 along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+
+
 #include <grammar.h>
 #include <stdio.h>
 #include <assert.h>
@@ -376,10 +396,16 @@ void first_iterate (gpointer key, gpointer val, gpointer data)
                            {
                              symbol_t* next_symbol;
                              next_symbol = next_symbols->data;
-                             /* TODO: Check this assertion is correct. */
-                             assert (next_symbol->terminal == FALSE);
+                             /*
+                              * This rule starts with a terminal. Ignore it.
+                              * We could add it as an optimization. TODO
+                              */
+                             if (next_symbol->terminal)
+                               {
+                                 rule_delete (next_rule);
+                               }
                              /* This is an indirect recursive rule. */
-                             if (next_symbol->value == symbol->value)
+                             else if (next_symbol->value == symbol->value)
                                {
                                  first_set->recursive =
                                    g_list_prepend (first_set->recursive,
@@ -457,7 +483,7 @@ void first_check (gpointer key, gpointer val, gpointer data)
  * We should iterate through the rules for each nonterminal until only
  * terminals are known to be in the first set of it.
  */
-GHashTable* grammar_first (Grammar* grammar)
+GHashTable* grammar_first (grammar_t* grammar)
 {
   GHashTable* first;
   gboolean stop;
@@ -474,7 +500,7 @@ GHashTable* grammar_first (Grammar* grammar)
   return first;
 }
 
-void put_key_on_list (gpointer key, gpointer val, gpointer data)
+static void put_key_on_list (gpointer key, gpointer val, gpointer data)
 {
   GList** l;
   l = (GList**) data;
@@ -497,3 +523,72 @@ GList* first_get (GHashTable* first, symbol_t* symbol)
   return l;
 
 }
+
+GList* first_rule (GHashTable* first, rule_t* rule)
+{
+
+  GHashTable* terminals;
+  GList* symbols;
+  GList* l;
+
+  l = NULL;
+
+  symbols = grammar_get_rule (rule);
+
+  terminals = g_hash_table_new_full (symbol_hash, symbol_equal, g_free, NULL);
+
+  while (symbols != NULL)
+    {
+      first_set_t* first_set;
+      symbol_t* symbol;
+      symbol = (symbol_t*) symbols->data;
+      if (symbol->terminal)
+       {
+         g_hash_table_insert (terminals, symbol_copy (symbol), NULL);
+         break;
+       }
+      if (!g_hash_table_lookup_extended (first, symbol, NULL,
+                                        (gpointer*) &first_set))
+       {
+         g_hash_table_destroy (terminals);
+         return NULL;
+       }
+      first_set_union (terminals, first_set->terminals);
+      if (first_set->has_empty == FALSE)
+       break;
+      symbols = g_list_next (symbols);
+    }
+
+  if (symbols == NULL)
+    l = g_list_prepend (l, symbol_new (TRUE, 0));
+  g_hash_table_foreach (terminals, put_key_on_list, &l);
+
+  g_hash_table_destroy (terminals);
+
+  return l;
+  
+}
+
+void first_print_symbol (gpointer key, gpointer val, gpointer data)
+{
+  symbol_t* symbol;
+  symbol = (symbol_t*) key;
+  fprintf (stdout, "%s\n", g_quark_to_string (symbol->value));
+}
+
+void first_print_set (gpointer key, gpointer val, gpointer data)
+{
+  symbol_t* symbol;
+  first_set_t* first_set;
+  symbol = (symbol_t*) key;
+  first_set = (first_set_t*) val;
+  fprintf (stdout, "FIRST of %s:\n", g_quark_to_string (symbol->value));
+  if (first_set->has_empty)
+    fprintf (stdout, "empty symbol\n");
+  g_hash_table_foreach (first_set->terminals, first_print_symbol, NULL);
+}
+
+void first_print (GHashTable* first)
+{
+  g_hash_table_foreach (first, first_print_set, NULL);
+}