Some work on derefs

3 files changed, 53 insertions, 18 deletions

diff --git a/src/reduce.c b/src/reduce.c
index 9e7520d..38baf06 100644
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -4,6 +4,7 @@
 #include <stdio.h>
 
 #include <term.h>
+#include <map.h>
 #include <reduce.h>
 #include <log.h>
 #include <assert.h>
@@ -13,26 +14,28 @@ static struct term *substitute(struct term *term, struct term *substitution,
 {
 	if (term->type == VAR) {
 		if (term->u.var.index == level) {
-			// TODO: deref index
+			term_deref_head(term);
 			return substitution;
 		} else {
 			return term;
 		}
 	} else if (term->type == ABS) {
+		hash_t previous = term->u.abs.term->hash;
 		struct term *new =
 			substitute(term->u.abs.term, substitution, level + 1);
-		if (term->u.abs.term->hash == new->hash)
+		if (previous == new->hash)
 			return term; // nothing changed
 		struct term *rehashed = term_rehash_abs(term, new);
 		term_rehash_parents(rehashed);
 		return rehashed;
 	} else if (term->type == APP) {
+		hash_t previous_lhs = term->u.app.lhs->hash;
+		hash_t previous_rhs = term->u.app.rhs->hash;
 		struct term *lhs =
 			substitute(term->u.app.lhs, substitution, level);
 		struct term *rhs =
 			substitute(term->u.app.rhs, substitution, level);
-		if (term->u.app.lhs->hash == lhs->hash &&
-		    term->u.app.rhs->hash == rhs->hash)
+		if (previous_lhs == lhs->hash && previous_rhs == rhs->hash)
 			return term; // nothing changed
 		struct term *rehashed = term_rehash_app(term, lhs, rhs);
 		term_rehash_parents(rehashed);
@@ -45,8 +48,12 @@ static struct term *substitute(struct term *term, struct term *substitution,
 // ([X] Y) -> X/Y
 struct term *reduce(struct term *term)
 {
-	assert(term->type == APP);
-	assert(term->u.app.lhs->type == ABS);
+	if (term->type != APP || term->u.app.lhs->type != ABS)
+		fatal("can't reduce non-beta-redex %d\n", term->type);
 
-	return substitute(term->u.app.lhs, term->u.app.rhs, -1);
+	map_delete(term->u.app.lhs->parents, term);
+	map_delete(term->u.app.rhs->parents, term);
+	struct term *reduced = substitute(term->u.app.lhs, term->u.app.rhs, -1);
+	term_deref_head(term);
+	return reduced;
 }
diff --git a/src/schedule.c b/src/schedule.c
index 93cd700..1362b1e 100644
--- a/src/schedule.c
+++ b/src/schedule.c
@@ -69,6 +69,8 @@ void schedule_add(struct term *term)
 void schedule(void)
 {
 	while (pqueue_size(queue) > 0) {
+		map_dump(map_all_terms());
+
 		// TODO: check finished programs
 		size_t position = choose_position();
 		struct term *term = pqueue_pop_at(queue, position);
diff --git a/src/term.c b/src/term.c
index a2f361b..bd0868c 100644
--- a/src/term.c
+++ b/src/term.c
@@ -9,6 +9,22 @@
 #include <term.h>
 #include <map.h>
 
+// doesn't care about ref count
+static void term_destroy_head(struct term *term)
+{
+	term_print(term);
+	fprintf(stderr, "\n");
+	map_delete(map_all_terms(), term);
+	map_destroy(term->parents);
+	free(term);
+}
+
+static void term_destroy_parent(void *item)
+{
+	struct term *term = *(struct term **)item;
+	term_destroy_head(term);
+}
+
 struct term *term_new(term_type_t type, hash_t hash, size_t depth)
 {
 	struct term *term = malloc(sizeof(*term));
@@ -18,7 +34,8 @@ struct term *term_new(term_type_t type, hash_t hash, size_t depth)
 	term->refs = 1;
 	term->hash = hash;
 	term->depth = depth;
-	term->parents = hashmap_new(sizeof(struct term *), 0, 0);
+	term->parents =
+		hashmap_new(sizeof(struct term *), 0, term_destroy_parent);
 	return term;
 }
 
@@ -55,12 +72,15 @@ struct term *term_rehash_abs(struct term *head, struct term *term)
 
 	struct term *match = map_get(map_all_terms(), res);
 	if (match) { // already exists
+		term_refer_head(match, head->depth);
+		term_deref_head(head);
 		return match;
 	} else { // create new
 		struct term *new = term_new(ABS, res, head->depth);
 		new->u.abs.term = term;
 		map_set(map_all_terms(), new);
 		map_set(term->parents, new);
+		term_deref_head(head);
 		return new;
 	}
 }
@@ -77,6 +97,8 @@ struct term *term_rehash_app(struct term *head, struct term *lhs,
 
 	struct term *match = map_get(map_all_terms(), res);
 	if (match) { // already exists
+		term_refer_head(match, head->depth);
+		term_deref(head);
 		return match;
 	} else { // create new
 		struct term *new = term_new(APP, res, head->depth);
@@ -85,6 +107,7 @@ struct term *term_rehash_app(struct term *head, struct term *lhs,
 		map_set(map_all_terms(), new);
 		map_set(lhs->parents, new);
 		map_set(rhs->parents, new);
+		term_deref_head(head);
 		return new;
 	}
 }
@@ -98,25 +121,30 @@ struct term *term_rehash_var(struct term *head, size_t index)
 
 	struct term *match = map_get(map_all_terms(), res);
 	if (match) { // already exists
+		term_refer_head(match, head->depth);
+		term_deref(head);
 		return match;
 	} else { // create new
 		struct term *new = term_new(APP, res, head->depth);
 		new->u.var.index = index;
 		map_set(map_all_terms(), new);
+		term_deref_head(head);
 		return new;
 	}
 }
 
 struct term *term_rehash(struct term *term)
 {
-	if (term->type == ABS) {
+	if (term->type == ABS)
 		return term_rehash_abs(term, term->u.abs.term);
-	} else if (term->type == APP) {
+
+	if (term->type == APP)
 		return term_rehash_app(term, term->u.app.lhs, term->u.app.rhs);
-	} else if (term->type == VAR) {
+
+	if (term->type == VAR)
 		return term_rehash_var(term, term->u.var.index);
-	}
-	return term;
+
+	fatal("invalid type %d\n", term->type);
 }
 
 // returns the direct parent
@@ -186,12 +214,10 @@ void term_refer(struct term *term, size_t depth)
 
 void term_deref_head(struct term *term)
 {
+	assert(term->refs);
 	term->refs--;
-	if (term->refs == 0) {
-		map_delete(map_all_terms(), term);
-		map_destroy(term->parents);
-		free(term);
-	}
+	if (!term->refs)
+		term_destroy_head(term);
 }
 
 void term_deref(struct term *term)