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 gboolean item_set_find (gpointer key, gpointer val, gpointer data)
114 return !g_hash_table_lookup_extended (data, key, NULL, NULL);
117 gboolean item_set_equal (gconstpointer a, gconstpointer b)
119 if (g_hash_table_size (a) != g_hash_table_size (b))
121 return (g_hash_table_find (a, item_set_find, b) == NULL);
124 void hash_item (gpointer key, gpointer val, gpointer data)
127 hash = (guint*) data;
128 *hash = *hash * 37 + item_hash (key);
131 guint item_set_hash (gconstpointer a)
134 g_hash_table_foreach (a, hash_item, &hash);
138 void item_set_add_each (gpointer key, gpointer val, gpointer data)
140 item_set_add (data, item_copy (key));
143 GHashTable* item_set_copy (GHashTable* item_set)
145 GHashTable* newitem_set;
146 newitem_set = item_set_new ();
147 g_hash_table_foreach (item_set, item_set_add_each, newitem_set);
152 void item_set_print_each (gpointer key, gpointer val, gpointer data)
157 void item_set_print (GHashTable* item_set)
159 g_hash_table_foreach (item_set, item_set_print_each, NULL);
163 void item_set_closure_step (GHashTable* item_set, Grammar* grammar,
166 if (item->dot != NULL)
169 symbol = (symbol_t*) item->dot->data;
170 if (symbol->terminal == FALSE)
173 rules = grammar_get_rules (grammar, symbol);
174 while (rules != NULL)
178 rule = rule_copy (rules->data);
179 newitem = item_new (symbol_copy (symbol), rule);
180 if (!item_set_add (item_set, newitem))
181 item_delete (newitem);
182 rules = g_list_next (rules);
188 void put_key_on_list (gpointer key, gpointer val, gpointer data)
192 *l = g_list_prepend (*l, key);
195 GHashTable* item_set_closure (GHashTable* item_set, Grammar* grammar)
200 size = g_hash_table_size (item_set);
205 g_hash_table_foreach (item_set, put_key_on_list, &l);
208 item_set_closure_step (item_set, grammar, l->data);
212 size = g_hash_table_size (item_set);
213 } while (last_size < size);
217 GHashTable* item_set_goto (GHashTable* item_set, Grammar* grammar,
221 GHashTable* newitem_set;
222 newitem_set = item_set_new ();
224 g_hash_table_foreach (item_set, put_key_on_list, &l);
228 item = item_copy (l->data);
229 if (item->dot == NULL || !symbol_equal (item->dot->data, symbol))
235 item->dot = g_list_next (item->dot);
236 if (!item_set_add (newitem_set, item))
241 return item_set_closure (newitem_set, grammar);
246 * This part is a little tricky. We can simply take an approach similar
247 * to the goto approach, adding a new set for every other set and grammar
248 * symbol every time we get a new set.
249 * Although a similar argument about the goto may apply (which is a very
250 * good reason to optimize it), the case for the collection is worse, since
251 * we will be building a new set for the number of sets in the collection
252 * times the number of symbol grammar. (Not building in fact, but computing
254 * Here is an approach that may work:
255 * For each *new* item set, we compute its gotos. Each goto is looked up
256 * in the collection. If it's a new item set, it's included in a list of
257 * new item sets. To compute the gotos of an item set, we should pick only
258 * the grammar symbols that appear in the items' dots. That solves the
259 * problem of getting a list of all the grammar symbols.
260 * So, there will be a list of item sets that we must iterate through. We
261 * add each new list to the hash table too, so we can look it up when we
262 * get a new one. When the list is finished, we are done and do not have to
263 * check the hash table size for each iteration.
264 * So, we need the following functions:
265 * One to check if an item set is already there and add it if it's not.
266 * One to get the symbols hash table, so we can put the computed goto
267 * there anyway. So, that's an add and a lookup.
271 * TODO: associate a number to each item set.
272 * Use a structure to the collection with a counter.
273 * Use another structure to the value in the hash table for each item set.
274 * This structure will have the symbol hash table (for the goto) and the
275 * number associated with the item set.
276 * In fact, the counter may be the hash table size.
285 state_t* state_new (gint code)
288 state = g_malloc (sizeof (state_t));
290 state->symbols = g_hash_table_new_full (symbol_hash, symbol_equal,
295 void state_delete (state_t* state)
297 g_hash_table_destroy (state->symbols);
301 GHashTable* item_collection_new ()
303 return g_hash_table_new_full (item_set_hash, item_set_equal,
304 g_hash_table_destroy, state_delete);
307 gboolean item_collection_add (GHashTable* collection, GHashTable* item_set)
309 if (!g_hash_table_lookup_extended (collection, item_set, NULL, NULL))
312 state = state_new (g_hash_table_size (collection));
313 g_hash_table_insert (collection, item_set, state);
319 state_t* item_collection_lookup (GHashTable* collection,
320 GHashTable* item_set)
323 if (!g_hash_table_lookup_extended (collection, item_set,
324 NULL, (gpointer*)&state))
332 void item_collection_print_each (gpointer key, gpointer val, gpointer data)
334 GHashTable* item_set;
336 item_set = (GHashTable*) key;
337 state = (state_t*) val;
338 fprintf (stdout, "Item %d:\n", state->code);
339 item_set_print (item_set);
340 fprintf (stdout, "\n");
343 void item_set_print_goto (gpointer key, gpointer val, gpointer data)
348 symbol = (symbol_t*) key;
349 code = GINT_TO_POINTER (val);
350 state = (state_t*) data;
351 fprintf (stdout, "GOTO (%d, %s) =\t %d\n", state->code,
352 g_quark_to_string (symbol->value), code);
355 void item_collection_print_goto (gpointer key, gpointer val, gpointer data)
358 state = (state_t*) val;
359 g_hash_table_foreach (state->symbols, item_set_print_goto, state);
360 fprintf (stdout, "\n");
363 void item_collection_print (GHashTable* collection)
365 g_hash_table_foreach (collection, item_collection_print_each, NULL);
366 g_hash_table_foreach (collection, item_collection_print_goto, NULL);
370 GHashTable* item_collection_goto (GHashTable* collection, Grammar* grammar,
371 GHashTable* item_set, symbol_t* symbol)
375 GHashTable* newitem_set;
376 GHashTable* goto_item_set;
377 GHashTable* return_item_set;
378 newitem_set = item_set_copy (item_set);
379 if (!item_collection_add (collection, newitem_set))
381 g_hash_table_destroy (newitem_set);
383 state = item_collection_lookup (collection, item_set);
384 if (g_hash_table_lookup_extended (state->symbols, symbol, NULL, NULL))
388 goto_item_set = item_set_goto (item_set, grammar, symbol);
389 if (!item_collection_add (collection, goto_item_set))
390 return_item_set = NULL;
392 return_item_set = goto_item_set;
393 goto_state = item_collection_lookup (collection, goto_item_set);
394 g_hash_table_insert (state->symbols, symbol,
395 GINT_TO_POINTER (goto_state->code));
396 return return_item_set;
399 void item_set_collection (Grammar* grammar, symbol_t* start)
401 GHashTable* collection;
402 GHashTable* item_set;
405 GList* new_item_sets;
407 rule_append (rule, symbol_copy (start));
408 item = item_new (symbol_new (FALSE, -1), rule);
409 item_set = item_set_new ();
410 item_set_add (item_set, item);
411 item_set_closure (item_set, grammar);
412 collection = g_hash_table_new_full (item_set_hash, item_set_equal,
413 g_hash_table_destroy, NULL);
414 item_collection_add (collection, item_set);
415 new_item_sets = g_list_append (NULL, item_set);
416 while (new_item_sets != NULL)
418 GHashTable* next_item_set;
419 GHashTable* new_item_set;
421 next_item_set = (GHashTable*) new_item_sets->data;
423 g_hash_table_foreach (next_item_set, put_key_on_list, &items);
424 while (items != NULL)
428 item = (item_t*) items->data;
429 if (item->dot != NULL)
431 symbol = (symbol_t*) item->dot->data;
433 item_collection_goto (collection, grammar,
434 next_item_set, symbol)) != NULL)
436 g_list_append (new_item_sets, new_item_set);
439 items = g_list_next (items);
442 new_item_sets = g_list_next (new_item_sets);
444 g_list_free (new_item_sets);
446 item_collection_print (collection);
448 g_hash_table_destroy (collection);