13 item_t* item_new (symbol_t* left, rule_t* right)
16 item = g_malloc (sizeof (item_t));
19 item->dot = grammar_get_rule (right);
23 item_t* item_copy (item_t* item)
27 newitem = item_new (symbol_copy (item->left), rule_copy (item->right));
28 n = g_list_position (grammar_get_rule (item->right), item->dot);
29 newitem->dot = g_list_nth (grammar_get_rule (newitem->right), n);
33 gint item_cmp (const item_t* a, const item_t* b)
38 if ((c = symbol_cmp (a->left, b->left)) != 0)
40 if ((c = rule_cmp (a->right, b->right)) != 0)
42 na = g_list_position (grammar_get_rule (a->right), a->dot);
43 nb = g_list_position (grammar_get_rule (b->right), b->dot);
51 gboolean item_equal (gconstpointer data1, gconstpointer data2)
53 return (item_cmp (data1, data2) == 0);
56 guint item_hash (gconstpointer data)
60 item = (item_t*) data;
61 hash = rule_hash (item->right) * 37 + symbol_hash (item->left);
65 void item_delete (item_t* item)
68 rule_delete (item->right);
73 void item_print (item_t* item)
76 fprintf (stdout, "%s -> ", g_quark_to_string (item->left->value));
77 l = grammar_rule_get (item->right);
81 symbol = (symbol_t*) l->data;
84 fprintf (stdout, ".");
86 fprintf (stdout, " %s ", g_quark_to_string (symbol->value));
88 if (item->dot == NULL)
90 fprintf (stdout, ".");
92 fprintf (stdout, "\n");
96 GHashTable* item_set_new ()
98 return g_hash_table_new_full (item_hash, item_equal, item_delete, NULL);
101 gboolean item_set_add (GHashTable* item_set, item_t* item)
103 if (!g_hash_table_lookup_extended (item_set, item, NULL, NULL))
105 g_hash_table_insert (item_set, item, NULL);
111 gboolean item_set_find (gpointer key, gpointer val, gpointer data)
113 return !g_hash_table_lookup_extended (data, key, NULL, NULL);
116 gboolean item_set_equal (gconstpointer a, gconstpointer b)
118 if (g_hash_table_size (a) != g_hash_table_size (b))
120 return (g_hash_table_find (a, item_set_find, b) == NULL);
123 void hash_item (gpointer key, gpointer val, gpointer data)
126 hash = (guint*) data;
127 *hash = *hash * 37 + item_hash (key);
130 guint item_set_hash (gconstpointer a)
133 g_hash_table_foreach (a, hash_item, &hash);
137 void item_set_add_each (gpointer key, gpointer val, gpointer data)
139 item_set_add (data, item_copy (key));
142 GHashTable* item_set_copy (GHashTable* item_set)
144 GHashTable* newitem_set;
145 newitem_set = item_set_new ();
146 g_hash_table_foreach (item_set, item_set_add_each, newitem_set);
151 void item_set_print_each (gpointer key, gpointer val, gpointer data)
156 void item_set_print (GHashTable* item_set)
158 g_hash_table_foreach (item_set, item_set_print_each, NULL);
162 void item_set_closure_step (GHashTable* item_set, Grammar* grammar,
165 if (item->dot != NULL)
168 symbol = (symbol_t*) item->dot->data;
169 if (symbol->terminal == FALSE)
172 rules = grammar_get_rules (grammar, symbol);
173 while (rules != NULL)
177 rule = rule_copy (rules->data);
178 newitem = item_new (symbol_copy (symbol), rule);
179 if (!item_set_add (item_set, newitem))
180 item_delete (newitem);
181 rules = g_list_next (rules);
187 void put_key_on_list (gpointer key, gpointer val, gpointer data)
191 *l = g_list_prepend (*l, key);
194 GHashTable* item_set_closure (GHashTable* item_set, Grammar* grammar)
199 size = g_hash_table_size (item_set);
204 g_hash_table_foreach (item_set, put_key_on_list, &l);
207 item_set_closure_step (item_set, grammar, l->data);
211 size = g_hash_table_size (item_set);
212 } while (last_size < size);
216 GHashTable* item_set_goto (GHashTable* item_set, Grammar* grammar,
220 GHashTable* newitem_set;
221 newitem_set = item_set_new ();
223 g_hash_table_foreach (item_set, put_key_on_list, &l);
227 item = item_copy (l->data);
228 if (item->dot == NULL || !symbol_equal (item->dot->data, symbol))
234 item->dot = g_list_next (item->dot);
235 if (!item_set_add (newitem_set, item))
240 return item_set_closure (newitem_set, grammar);
245 * This part is a little tricky. We can simply take an approach similar
246 * to the goto approach, adding a new set for every other set and grammar
247 * symbol every time we get a new set.
248 * Although a similar argument about the goto may apply (which is a very
249 * good reason to optimize it), the case for the collection is worse, since
250 * we will be building a new set for the number of sets in the collection
251 * times the number of symbol grammar. (Not building in fact, but computing
253 * Here is an approach that may work:
254 * For each *new* item set, we compute its gotos. Each goto is looked up
255 * in the collection. If it's a new item set, it's included in a list of
256 * new item sets. To compute the gotos of an item set, we should pick only
257 * the grammar symbols that appear in the items' dots. That solves the
258 * problem of getting a list of all the grammar symbols.
259 * So, there will be a list of item sets that we must iterate through. We
260 * add each new list to the hash table too, so we can look it up when we
261 * get a new one. When the list is finished, we are done and do not have to
262 * check the hash table size for each iteration.
263 * So, we need the following functions:
264 * One to check if an item set is already there and add it if it's not.
265 * One to get the symbols hash table, so we can put the computed goto
266 * there anyway. So, that's an add and a lookup.
270 * TODO: associate a number to each item set.
271 * Use a structure to the collection with a counter.
272 * Use another structure to the value in the hash table for each item set.
273 * This structure will have the symbol hash table (for the goto) and the
274 * number associated with the item set.
275 * In fact, the counter may be the hash table size.
284 state_t* state_new (gint code)
287 state = g_malloc (sizeof (state_t));
289 state->symbols = g_hash_table_new_full (symbol_hash, symbol_equal,
294 void state_delete (state_t* state)
296 g_hash_table_destroy (state->symbols);
300 GHashTable* item_collection_new ()
302 return g_hash_table_new_full (item_set_hash, item_set_equal,
303 g_hash_table_destroy, state_delete);
306 gboolean item_collection_add (GHashTable* collection, GHashTable* item_set)
308 if (!g_hash_table_lookup_extended (collection, item_set, NULL, NULL))
311 state = state_new (g_hash_table_size (collection));
312 g_hash_table_insert (collection, item_set, state);
318 state_t* item_collection_lookup (GHashTable* collection,
319 GHashTable* item_set)
322 if (!g_hash_table_lookup_extended (collection, item_set,
323 NULL, (gpointer*)&state))
331 void item_collection_print_each (gpointer key, gpointer val, gpointer data)
333 GHashTable* item_set;
335 item_set = (GHashTable*) key;
336 state = (state_t*) val;
337 fprintf (stdout, "Item %d:\n", state->code);
338 item_set_print (item_set);
339 fprintf (stdout, "\n");
342 void item_set_print_goto (gpointer key, gpointer val, gpointer data)
347 symbol = (symbol_t*) symbol;
348 code = GINT_TO_POINTER (val);
349 state = (state_t*) data;
350 fprintf (stdout, "GOTO (%d, %s) =\t %d\n", state->code,
351 g_quark_to_string (symbol->value), code);
354 void item_collection_print_goto (gpointer key, gpointer val, gpointer data)
357 state = (state_t*) val;
358 g_hash_table_foreach (state->symbols, item_set_print_goto, state);
359 fprintf (stdout, "\n");
362 void item_collection_print (GHashTable* collection)
364 g_hash_table_foreach (collection, item_collection_print_each, NULL);
365 g_hash_table_foreach (collection, item_collection_print_goto, NULL);
369 GHashTable* item_collection_goto (GHashTable* collection, Grammar* grammar,
370 GHashTable* item_set, symbol_t* symbol)
374 GHashTable* newitem_set;
375 GHashTable* goto_item_set;
376 GHashTable* return_item_set;
377 newitem_set = item_set_copy (item_set);
378 if (!item_collection_add (collection, newitem_set))
380 g_hash_table_destroy (newitem_set);
382 state = item_collection_lookup (collection, item_set);
383 if (g_hash_table_lookup_extended (state->symbols, symbol, NULL, NULL))
387 goto_item_set = item_set_goto (item_set, grammar, symbol);
388 if (!item_collection_add (collection, goto_item_set))
389 return_item_set = NULL;
391 return_item_set = goto_item_set;
392 goto_state = item_collection_lookup (collection, goto_item_set);
393 g_hash_table_insert (state->symbols, symbol,
394 GINT_TO_POINTER (goto_state->code));
395 return return_item_set;
398 void item_set_collection (Grammar* grammar, symbol_t* start)
400 GHashTable* collection;
401 GHashTable* item_set;
404 GList* new_item_sets;
406 rule_append (rule, symbol_copy (start));
407 item = item_new (symbol_new (FALSE, -1), rule);
408 item_set = item_set_new ();
409 item_set_add (item_set, item);
410 item_set_closure (item_set, grammar);
411 collection = g_hash_table_new_full (item_set_hash, item_set_equal,
412 g_hash_table_destroy, NULL);
413 item_collection_add (collection, item_set);
414 new_item_sets = g_list_append (NULL, item_set);
415 while (new_item_sets != NULL)
417 GHashTable* next_item_set;
418 GHashTable* new_item_set;
420 next_item_set = (GHashTable*) new_item_sets->data;
422 g_hash_table_foreach (next_item_set, put_key_on_list, &items);
423 while (items != NULL)
427 item = (item_t*) items->data;
428 if (item->dot != NULL)
430 symbol = (symbol_t*) item->dot->data;
432 item_collection_goto (collection, grammar,
433 next_item_set, symbol)) != NULL)
435 g_list_append (new_item_sets, new_item_set);
438 items = g_list_next (items);
441 new_item_sets = g_list_next (new_item_sets);
443 g_list_free (new_item_sets);
445 item_collection_print (collection);
447 g_hash_table_destroy (collection);