1 files changed, 89 insertions, 20 deletions

diff --git a/src/term.c b/src/term.c
index 903ee8a..d52171a 100644
--- a/src/term.c
+++ b/src/term.c
@@ -3,9 +3,11 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <assert.h>
 
 #include <log.h>
 #include <term.h>
+#include <map.h>
 
 struct term *term_new(term_type_t type, hash_t hash, size_t depth)
 {
@@ -19,13 +21,6 @@ struct term *term_new(term_type_t type, hash_t hash, size_t depth)
 	return term;
 }
 
-void term_refer(struct term *term, size_t depth)
-{
-	term->refs++;
-	if (depth < term->depth) // lower depths are more important
-		term->depth = depth;
-}
-
 void term_print(struct term *term)
 {
 	switch (term->type) {
@@ -49,16 +44,90 @@ void term_print(struct term *term)
 	}
 }
 
-/* void deref_term(struct term *term) */
-/* { */
-/* 	if (term->type == ABS) { */
-/* 		deref_term(term->u.abs.term); */
-/* 	} else if (term->type == APP) { */
-/* 		deref_term(term->u.app.lhs); */
-/* 		deref_term(term->u.app.rhs); */
-/* 	} */
-
-/* 	// TODO: remove from hashmap? */
-/* 	if (--term->refs == 0) */
-/* 		free(term); */
-/* } */
+struct term *term_rehash_abs(struct term *head, struct term *term)
+{
+	if (head->u.abs.term->hash == term->hash)
+		return head;
+
+	hash_t res =
+		hash((uint8_t *)&head->type, sizeof(head->type), term->hash);
+
+	assert(res != head->hash);
+
+	struct term *match = map_get(res);
+	if (match) { // already exists
+		term_refer(match, head->depth);
+		term_deref(head);
+		return match;
+	} else { // create new
+		struct term *new = term_new(ABS, res, head->depth);
+		new->u.abs.term = term;
+		term_refer(term, head->depth + 1);
+		term_deref(head);
+		return new;
+	}
+}
+
+struct term *term_rehash_app(struct term *head, struct term *lhs,
+			     struct term *rhs)
+{
+	if (head->u.app.lhs->hash == lhs->hash &&
+	    head->u.app.rhs->hash == rhs->hash)
+		return head;
+
+	hash_t res =
+		hash((uint8_t *)&head->type, sizeof(head->type), lhs->hash);
+	res = hash((uint8_t *)&res, sizeof(res), rhs->hash);
+
+	assert(res != head->hash);
+
+	struct term *match = map_get(res);
+	if (match) { // already exists
+		term_refer(match, head->depth);
+		term_deref(head);
+		return match;
+	} else { // create new
+		struct term *new = term_new(APP, res, head->depth);
+		new->u.app.lhs = lhs;
+		new->u.app.rhs = rhs;
+		if (head->u.app.lhs->hash != lhs->hash)
+			term_refer(lhs, head->depth + 1);
+		if (head->u.app.rhs->hash != rhs->hash)
+			term_refer(rhs, head->depth + 1);
+		term_deref(head);
+		return new;
+	}
+}
+
+void term_refer_head(struct term *term, size_t depth)
+{
+	term->refs++;
+	if (depth < term->depth) // lower depths are more important
+		term->depth = depth;
+}
+
+void term_refer(struct term *term, size_t depth)
+{
+	if (term->type == ABS) {
+		term_refer(term->u.abs.term, depth + 1);
+	} else if (term->type == APP) {
+		term_refer(term->u.app.lhs, depth + 1);
+		term_refer(term->u.app.rhs, depth + 1);
+	}
+
+	term_refer_head(term, depth);
+}
+
+void term_deref(struct term *term)
+{
+	if (term->type == ABS) {
+		term_deref(term->u.abs.term);
+	} else if (term->type == APP) {
+		term_deref(term->u.app.lhs);
+		term_deref(term->u.app.rhs);
+	}
+
+	// TODO: remove from hashmap?
+	if (--term->refs == 0)
+		free(term);
+}