From e18525f5d6de86773df9d72dd5d5f9e2c6dca581 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 12 Feb 2014 03:01:15 -0800
Subject: * hash.c (struct hash): New member, equal_fun. (hash_equal_op): Short
 circuited logic: whenever we pull identical cells from either hash, we don't
 have to go through the pending lookaside list. (make_hash,
 make_similar_hash): Initialize new structure member.

---
 ChangeLog |  8 ++++++++
 hash.c    | 11 +++++++++++
 2 files changed, 19 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index b04577bc..9e418e8c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2014-02-12  Kaz Kylheku  <kaz@kylheku.com>
+
+	* hash.c (struct hash): New member, equal_fun.
+	(hash_equal_op): Short circuited logic: whenever we pull
+	identical cells from either hash, we don't have to go
+	through the pending lookaside list.
+	(make_hash, make_similar_hash): Initialize new structure member.
+
 2014-02-12  Kaz Kylheku  <kaz@kylheku.com>
 
 	* hash.c (hash_equal_op, hash_hash_op): New static functions.
diff --git a/hash.c b/hash.c
index cd91ad5e..c74a6294 100644
--- a/hash.c
+++ b/hash.c
@@ -55,6 +55,7 @@ struct hash {
   cnum count;
   val userdata;
   cnum (*hash_fun)(val);
+  val (*equal_fun)(val, val);
   val (*assoc_fun)(val key, val list);
   val *(*acons_new_l_fun)(val key, val *new_p, val *list);
 };
@@ -247,6 +248,14 @@ static val hash_equal_op(val left, val right)
     val ncons = or2(pop(&free_conses), cons(nil, nil));
     val found;
 
+    /*
+     * Short circuit the logic if we have two identical cells;
+     * no need to go through the pending list.
+     */
+
+    if (l->equal_fun(car(lcell), car(rcell)) && equal(cdr(lcell), cdr(rcell)))
+      continue;
+
     /*
      * Try to find a cell matching the left cell on the pending list by key.
      * If it is found, and the associated datum is equal, then remove it from
@@ -460,6 +469,7 @@ val make_hash(val weak_keys, val weak_vals, val equal_based)
     h->userdata = nil;
 
     h->hash_fun = equal_based ? equal_hash : eql_hash;
+    h->equal_fun = equal_based ? equal : eql;
     h->assoc_fun = equal_based ? assoc : assql;
     h->acons_new_l_fun = equal_based ? acons_new_l : aconsql_new_l;
 
@@ -482,6 +492,7 @@ val make_similar_hash(val existing)
 
   h->flags = ex->flags;
   h->hash_fun = ex->hash_fun;
+  h->equal_fun = ex->equal_fun;
   h->assoc_fun = ex->assoc_fun;
   h->acons_new_l_fun = ex->acons_new_l_fun;
 
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