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_get_rule (item->right);
81 symbol = (symbol_t*) l->data;
84 fprintf (stdout, ".");
86 fprintf (stdout, " %s ", g_quark_to_string (symbol->value));
89 if (item->dot == NULL)
91 fprintf (stdout, ".");
93 fprintf (stdout, "\n");
97 GHashTable* item_set_new ()
99 return g_hash_table_new_full (item_hash, item_equal, item_delete, NULL);
102 gboolean item_set_add (GHashTable* item_set, item_t* item)
104 if (!g_hash_table_lookup_extended (item_set, item, NULL, NULL))
106 g_hash_table_insert (item_set, item, NULL);
112 void put_key_on_list (gpointer key, gpointer val, gpointer data)
116 *l = g_list_prepend (*l, key);
119 gboolean item_set_equal (gconstpointer a, gconstpointer b)
123 if (g_hash_table_size (a) != g_hash_table_size (b))
126 g_hash_table_foreach (a, put_key_on_list, (gpointer) &l);
128 while (l != NULL && equal == TRUE)
130 equal = g_hash_table_lookup_extended (b, l->data, NULL, NULL);
137 void hash_item (gpointer key, gpointer val, gpointer data)
140 hash = (guint*) data;
141 *hash = *hash * 37 + item_hash (key);
144 guint item_set_hash (gconstpointer a)
147 g_hash_table_foreach (a, hash_item, &hash);
151 void item_set_add_each (gpointer key, gpointer val, gpointer data)
153 item_set_add (data, item_copy (key));
156 GHashTable* item_set_copy (GHashTable* item_set)
158 GHashTable* newitem_set;
159 newitem_set = item_set_new ();
160 g_hash_table_foreach (item_set, item_set_add_each, newitem_set);
165 void item_set_print_each (gpointer key, gpointer val, gpointer data)
170 void item_set_print (GHashTable* item_set)
172 g_hash_table_foreach (item_set, item_set_print_each, NULL);
176 void item_set_closure_step (GHashTable* item_set, Grammar* grammar,
179 if (item->dot != NULL)
182 symbol = (symbol_t*) item->dot->data;
183 if (symbol->terminal == FALSE)
186 rules = grammar_get_rules (grammar, symbol);
187 while (rules != NULL)
191 rule = rule_copy (rules->data);
192 newitem = item_new (symbol_copy (symbol), rule);
193 if (!item_set_add (item_set, newitem))
194 item_delete (newitem);
195 rules = g_list_next (rules);
201 GHashTable* item_set_closure (GHashTable* item_set, Grammar* grammar)
206 size = g_hash_table_size (item_set);
211 g_hash_table_foreach (item_set, put_key_on_list, &l);
214 item_set_closure_step (item_set, grammar, l->data);
218 size = g_hash_table_size (item_set);
219 } while (last_size < size);
223 GHashTable* item_set_goto (GHashTable* item_set, Grammar* grammar,
227 GHashTable* newitem_set;
228 newitem_set = item_set_new ();
230 g_hash_table_foreach (item_set, put_key_on_list, &l);
234 item = item_copy (l->data);
235 if (item->dot == NULL || !symbol_equal (item->dot->data, symbol))
241 item->dot = g_list_next (item->dot);
242 if (!item_set_add (newitem_set, item))
247 return item_set_closure (newitem_set, grammar);
252 * This part is a little tricky. We can simply take an approach similar
253 * to the goto approach, adding a new set for every other set and grammar
254 * symbol every time we get a new set.
255 * Although a similar argument about the goto may apply (which is a very
256 * good reason to optimize it), the case for the collection is worse, since
257 * we will be building a new set for the number of sets in the collection
258 * times the number of symbol grammar. (Not building in fact, but computing
260 * Here is an approach that may work:
261 * For each *new* item set, we compute its gotos. Each goto is looked up
262 * in the collection. If it's a new item set, it's included in a list of
263 * new item sets. To compute the gotos of an item set, we should pick only
264 * the grammar symbols that appear in the items' dots. That solves the
265 * problem of getting a list of all the grammar symbols.
266 * So, there will be a list of item sets that we must iterate through. We
267 * add each new list to the hash table too, so we can look it up when we
268 * get a new one. When the list is finished, we are done and do not have to
269 * check the hash table size for each iteration.
270 * So, we need the following functions:
271 * One to check if an item set is already there and add it if it's not.
272 * One to get the symbols hash table, so we can put the computed goto
273 * there anyway. So, that's an add and a lookup.
277 * TODO: associate a number to each item set.
278 * Use a structure to the collection with a counter.
279 * Use another structure to the value in the hash table for each item set.
280 * This structure will have the symbol hash table (for the goto) and the
281 * number associated with the item set.
282 * In fact, the counter may be the hash table size.
291 state_t* state_new (gint code)
294 state = g_malloc (sizeof (state_t));
296 state->symbols = g_hash_table_new_full (symbol_hash, symbol_equal,
301 void state_delete (state_t* state)
303 g_hash_table_destroy (state->symbols);
307 GHashTable* item_collection_new ()
309 return g_hash_table_new_full (item_set_hash, item_set_equal,
310 g_hash_table_destroy, state_delete);
313 gboolean item_collection_add (GHashTable* collection, GHashTable* item_set)
315 if (!g_hash_table_lookup_extended (collection, item_set, NULL, NULL))
318 state = state_new (g_hash_table_size (collection));
319 g_hash_table_insert (collection, item_set, state);
325 state_t* item_collection_lookup (GHashTable* collection,
326 GHashTable* item_set)
329 if (!g_hash_table_lookup_extended (collection, item_set,
330 NULL, (gpointer*)&state))
338 void item_collection_print_each (gpointer key, gpointer val, gpointer data)
340 GHashTable* item_set;
342 item_set = (GHashTable*) key;
343 state = (state_t*) val;
344 fprintf (stdout, "Item %d:\n", state->code);
345 item_set_print (item_set);
346 fprintf (stdout, "\n");
349 void item_set_print_goto (gpointer key, gpointer val, gpointer data)
354 symbol = (symbol_t*) key;
355 code = GINT_TO_POINTER (val);
356 state = (state_t*) data;
357 fprintf (stdout, "GOTO (%d, %s) =\t %d\n", state->code,
358 g_quark_to_string (symbol->value), code);
361 void item_collection_print_goto (gpointer key, gpointer val, gpointer data)
364 state = (state_t*) val;
365 g_hash_table_foreach (state->symbols, item_set_print_goto, state);
366 fprintf (stdout, "\n");
369 void item_collection_print (GHashTable* collection)
371 g_hash_table_foreach (collection, item_collection_print_each, NULL);
372 g_hash_table_foreach (collection, item_collection_print_goto, NULL);
376 GHashTable* item_collection_goto (GHashTable* collection, Grammar* grammar,
377 GHashTable* item_set, symbol_t* symbol)
381 GHashTable* newitem_set;
382 GHashTable* goto_item_set;
383 GHashTable* return_item_set;
384 newitem_set = item_set_copy (item_set);
385 if (!item_collection_add (collection, newitem_set))
387 g_hash_table_destroy (newitem_set);
389 state = item_collection_lookup (collection, item_set);
390 if (g_hash_table_lookup_extended (state->symbols, symbol, NULL, NULL))
394 goto_item_set = item_set_goto (item_set, grammar, symbol);
395 if (!item_collection_add (collection, goto_item_set))
396 return_item_set = NULL;
398 return_item_set = goto_item_set;
399 goto_state = item_collection_lookup (collection, goto_item_set);
400 g_hash_table_insert (state->symbols, symbol,
401 GINT_TO_POINTER (goto_state->code));
402 return return_item_set;
405 void item_set_collection (Grammar* grammar, symbol_t* start)
407 GHashTable* collection;
408 GHashTable* item_set;
411 GList* new_item_sets;
413 rule_append (rule, symbol_copy (start));
414 item = item_new (symbol_new (FALSE, -1), rule);
415 item_set = item_set_new ();
416 item_set_add (item_set, item);
417 item_set_closure (item_set, grammar);
418 collection = g_hash_table_new_full (item_set_hash, item_set_equal,
419 g_hash_table_destroy, NULL);
420 item_collection_add (collection, item_set);
421 new_item_sets = g_list_append (NULL, item_set);
422 while (new_item_sets != NULL)
424 GHashTable* next_item_set;
425 GHashTable* new_item_set;
427 next_item_set = (GHashTable*) new_item_sets->data;
429 g_hash_table_foreach (next_item_set, put_key_on_list, &items);
430 while (items != NULL)
434 item = (item_t*) items->data;
435 if (item->dot != NULL)
437 symbol = (symbol_t*) item->dot->data;
439 item_collection_goto (collection, grammar,
440 next_item_set, symbol)) != NULL)
442 g_list_append (new_item_sets, new_item_set);
445 items = g_list_next (items);
448 new_item_sets = g_list_next (new_item_sets);
450 g_list_free (new_item_sets);
452 item_collection_print (collection);
454 g_hash_table_destroy (collection);