X-Git-Url: http://git.cascardo.info/?p=cascardo%2Fgrammar.git;a=blobdiff_plain;f=item.c;h=657e764990fd045596ceaec98235db55cfeb7d58;hp=c089253eb199342da251173244a7122f8c997c56;hb=25f6db6a70f3d138da9effa3e8c945e57cd83572;hpb=58c67aca3f0c6090ae9fba5d872d041d514c6b8f diff --git a/item.c b/item.c index c089253..657e764 100644 --- a/item.c +++ b/item.c @@ -1,22 +1,18 @@ #include +#include +#include #ifdef DEBUG #include #endif -typedef struct -{ - symbol_t* left; - rule_t* right; - GList* dot; -} item_t; - -item_t* item_new (symbol_t* left, rule_t* right) +item_t* item_new (symbol_t* left, rule_t* right, symbol_t* lookahead) { item_t* item; item = g_malloc (sizeof (item_t)); item->left = left; item->right = right; item->dot = grammar_get_rule (right); + item->lookahead = lookahead; return item; } @@ -24,7 +20,8 @@ item_t* item_copy (item_t* item) { item_t* newitem; int n; - newitem = item_new (symbol_copy (item->left), rule_copy (item->right)); + newitem = item_new (symbol_copy (item->left), rule_copy (item->right), + symbol_copy (item->lookahead)); n = g_list_position (grammar_get_rule (item->right), item->dot); newitem->dot = g_list_nth (grammar_get_rule (newitem->right), n); return newitem; @@ -39,6 +36,8 @@ gint item_cmp (const item_t* a, const item_t* b) return c; if ((c = rule_cmp (a->right, b->right)) != 0) return c; + if ((c = symbol_cmp (a->lookahead, b->lookahead)) != 0) + return c; na = g_list_position (grammar_get_rule (a->right), a->dot); nb = g_list_position (grammar_get_rule (b->right), b->dot); if (na < nb) @@ -59,6 +58,7 @@ guint item_hash (gconstpointer data) guint hash; item = (item_t*) data; hash = rule_hash (item->right) * 37 + symbol_hash (item->left); + hash = hash * 37 + symbol_hash (item->lookahead); return hash; } @@ -66,6 +66,7 @@ void item_delete (item_t* item) { g_free (item->left); rule_delete (item->right); + g_free (item->lookahead); g_free (item); } @@ -90,7 +91,7 @@ void item_print (item_t* item) { fprintf (stdout, "."); } - fprintf (stdout, "\n"); + fprintf (stdout, ", %s\n", g_quark_to_string (item->lookahead->value)); } #endif @@ -173,8 +174,25 @@ void item_set_print (GHashTable* item_set) } #endif +rule_t* rule_new_item (item_t* item) +{ + + rule_t* rule; + GList* l; + rule = rule_new (); + l = g_list_next (item->dot); + while (l != NULL) + { + rule_append (rule, symbol_copy (l->data)); + l = g_list_next (l); + } + rule_append (rule, symbol_copy (item->lookahead)); + return rule; + +} + void item_set_closure_step (GHashTable* item_set, grammar_t* grammar, - item_t* item) + GHashTable* first, item_t* item) { if (item->dot != NULL) { @@ -183,22 +201,36 @@ void item_set_closure_step (GHashTable* item_set, grammar_t* grammar, if (symbol->terminal == FALSE) { GList* rules; + GList* terminals; + rule_t* rule; + rule = rule_new_item (item); + terminals = first_rule (first, rule); + rule_delete (rule); rules = grammar_get_rules (grammar, symbol); while (rules != NULL) { - rule_t* rule; - item_t* newitem; - rule = rule_copy (rules->data); - newitem = item_new (symbol_copy (symbol), rule); - if (!item_set_add (item_set, newitem)) - item_delete (newitem); + GList* lookahead; + lookahead = terminals; + while (lookahead != NULL) + { + rule_t* rule; + item_t* newitem; + rule = rule_copy (rules->data); + newitem = item_new (symbol_copy (symbol), rule, + symbol_copy (lookahead->data)); + if (!item_set_add (item_set, newitem)) + item_delete (newitem); + lookahead = g_list_next (lookahead); + } rules = g_list_next (rules); } + g_list_free (terminals); } } } -GHashTable* item_set_closure (GHashTable* item_set, grammar_t* grammar) +GHashTable* item_set_closure (GHashTable* item_set, grammar_t* grammar, + GHashTable* first) { int size; int last_size; @@ -211,7 +243,7 @@ GHashTable* item_set_closure (GHashTable* item_set, grammar_t* grammar) g_hash_table_foreach (item_set, put_key_on_list, &l); while (l != NULL) { - item_set_closure_step (item_set, grammar, l->data); + item_set_closure_step (item_set, grammar, first, l->data); l = g_list_next (l); } g_list_free (l); @@ -221,7 +253,7 @@ GHashTable* item_set_closure (GHashTable* item_set, grammar_t* grammar) } GHashTable* item_set_goto (GHashTable* item_set, grammar_t* grammar, - symbol_t* symbol) + GHashTable* first, symbol_t* symbol) { GList* l; GHashTable* newitem_set; @@ -244,7 +276,7 @@ GHashTable* item_set_goto (GHashTable* item_set, grammar_t* grammar, } l = g_list_next (l); } - return item_set_closure (newitem_set, grammar); + return item_set_closure (newitem_set, grammar, first); } @@ -315,13 +347,13 @@ GHashTable* item_collection_lookup (GHashTable* collection, return symbols; } -#define HASH_ITEM_SET(item_set) (((GPOINTER_TO_INT(item_set) & 0x3f00) >> 8)) +#define HASH_ITEM_SET(item_set) (item_set) #ifdef DEBUG void item_collection_print_each (gpointer key, gpointer val, gpointer data) { GHashTable* item_set; item_set = (GHashTable*) key; - fprintf (stdout, "Item %x:\n", HASH_ITEM_SET(key)); + fprintf (stdout, "Item %p:\n", HASH_ITEM_SET(key)); item_set_print (item_set); fprintf (stdout, "\n"); } @@ -330,7 +362,7 @@ void item_set_print_goto (gpointer key, gpointer val, gpointer data) { symbol_t* symbol; symbol = (symbol_t*) key; - fprintf (stdout, "GOTO (%x, %s) =\t %x\n", HASH_ITEM_SET(data), + fprintf (stdout, "GOTO (%p, %s) =\t %p\n", HASH_ITEM_SET(data), g_quark_to_string (symbol->value), HASH_ITEM_SET(val)); } @@ -350,23 +382,47 @@ void item_collection_print (GHashTable* collection) #endif GHashTable* item_collection_goto (GHashTable* collection, grammar_t* grammar, - GHashTable* item_set, symbol_t* symbol) + GHashTable* first, GHashTable* item_set, + symbol_t* symbol) { + GHashTable* symbols; GHashTable* newitem_set; GHashTable* goto_item_set; GHashTable* old_item_set; + + /* + * Is it a new item set? Why should we insert a copy of it? Do we + * destroy the original later? + * + * TODO: Check why this code was once here. WTF! Caused some damn + * bug. + */ + /* newitem_set = item_set_copy (item_set); if (!item_collection_add (collection, newitem_set, NULL)) { g_hash_table_destroy (newitem_set); } + */ + + /* + * Is there a computed goto from this item set with this symbol + * already? + */ symbols = item_collection_lookup (collection, item_set); if (g_hash_table_lookup_extended (symbols, symbol, NULL, NULL)) { return NULL; } - goto_item_set = item_set_goto (item_set, grammar, symbol); + + /* + * If the computed goto already exists in the table, retrieve it and + * add the entry in the table pointing to it instead of the newly + * computed item set. Destroy the new copy. We don't need it. Only + * return the computed goto if it's a new item set. + */ + goto_item_set = item_set_goto (item_set, grammar, first, symbol); if (!item_collection_add (collection, goto_item_set, &old_item_set)) { g_hash_table_insert (symbols, symbol, old_item_set); @@ -380,54 +436,101 @@ GHashTable* item_collection_goto (GHashTable* collection, grammar_t* grammar, } } -void item_set_collection (grammar_t* grammar, symbol_t* start) +void get_symbol_at_dot (gpointer key, gpointer val, gpointer data) { + item_t* item; + GHashTable* symbols; + symbol_t* symbol; + item = (item_t*) key; + symbols = (GHashTable*) data; + if (item->dot != NULL) + { + symbol = item->dot->data; + if (!g_hash_table_lookup_extended (symbols, symbol, NULL, NULL)) + { + g_hash_table_insert (symbols, symbol, NULL); + } + } +} + +/* Get the symbols at the dot in this item set */ +GList* item_set_symbols_at_dot (GHashTable* item_set) +{ + GHashTable* symbols; + GList* symbols_list; + symbols_list = NULL; + symbols = g_hash_table_new_full (symbol_hash, symbol_equal, + NULL, NULL); + g_hash_table_foreach (item_set, get_symbol_at_dot, symbols); + g_hash_table_foreach (symbols, put_key_on_list, &symbols_list); + g_hash_table_destroy (symbols); + return symbols_list; +} + +GHashTable* item_set_collection (grammar_t* grammar, GHashTable* first, + symbol_t* start) +{ + GHashTable* collection; GHashTable* item_set; item_t* item; rule_t* rule; GList* new_item_sets; + + /* Augmented grammar has start symbol S' -> S */ rule = rule_new (); rule_append (rule, symbol_copy (start)); - item = item_new (symbol_new (FALSE, -1), rule); + + /* First item set is the closure of the item set with S' -> . S , $ */ + item = item_new (symbol_new (FALSE, -1), rule, symbol_new (TRUE, 0)); item_set = item_set_new (); item_set_add (item_set, item); - item_set_closure (item_set, grammar); + item_set_closure (item_set, grammar, first); + + /* Insert first item set in the collection of item sets and start working */ collection = g_hash_table_new_full (item_set_hash, item_set_equal, g_hash_table_destroy, NULL); item_collection_add (collection, item_set, NULL); + new_item_sets = g_list_append (NULL, item_set); + while (new_item_sets != NULL) { GHashTable* next_item_set; GHashTable* new_item_set; - GList* items; + GList* symbols; + /* + * For each item, compute the goto for the symbol at its + * dot. Should be done only for each symbol at a dot in the + * whole item set. Only new item sets are put in the new item + * sets list. Check item_collection_goto. + * + * TODO: Only do this for each symbol at a dot in the item set. + */ next_item_set = (GHashTable*) new_item_sets->data; - items = NULL; - g_hash_table_foreach (next_item_set, put_key_on_list, &items); - while (items != NULL) + symbols = item_set_symbols_at_dot (next_item_set); + while (symbols != NULL) { - item_t* item; symbol_t* symbol; - item = (item_t*) items->data; - if (item->dot != NULL) + symbol = (symbol_t*) symbols->data; + if ((new_item_set = + item_collection_goto (collection, grammar, first, + next_item_set, symbol)) != NULL) { - symbol = (symbol_t*) item->dot->data; - if ((new_item_set = - item_collection_goto (collection, grammar, - next_item_set, symbol)) != NULL) - { - g_list_append (new_item_sets, new_item_set); - } + g_list_append (new_item_sets, new_item_set); } - items = g_list_next (items); + symbols = g_list_next (symbols); } - g_list_free (items); + g_list_free (symbols); new_item_sets = g_list_next (new_item_sets); } + g_list_free (new_item_sets); + #ifdef DEBUG item_collection_print (collection); #endif - g_hash_table_destroy (collection); + + return collection; + }