From 6e9733afec2600acf71ca3c315b0c270023e8081 Mon Sep 17 00:00:00 2001
From: Danny Yoo <dyoo@cs.wpi.edu>
Date: Fri, 4 Nov 2011 18:05:21 -0400
Subject: [PATCH] cheaply computing equal-hash-table codes.

---
 js-assembler/runtime-src/baselib-hashes.js |  7 ++++---
 tests/more-tests/hash-code.rkt             | 18 +++++++++---------
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/js-assembler/runtime-src/baselib-hashes.js b/js-assembler/runtime-src/baselib-hashes.js
index 4ee70ea..69407a7 100644
--- a/js-assembler/runtime-src/baselib-hashes.js
+++ b/js-assembler/runtime-src/baselib-hashes.js
@@ -178,9 +178,9 @@
     // Returns a JavaScript number.
     var getEqualHashCode = function (x, depth) {
         var i, t, k = 0;
-        if (depth === undefined) { depth = 0; }
+        if (depth === undefined) { depth = [0]; }
 
-        if (depth > MAX_HASH_DEPTH) { return 0; }
+        if (depth[0] > MAX_HASH_DEPTH) { return 0; }
 
         if (baselib.numbers.isNumber(x)) {
             return hashMix(baselib.numbers.toFixnum(x));
@@ -201,7 +201,8 @@
 
         if (typeof(x) === 'object' &&
             typeof(x.hashCode) === 'function') {
-            return x.hashCode(depth + 1);
+            depth[0] = depth[0] + 1;
+            return x.hashCode(depth);
         }
         return 0;
     };
diff --git a/tests/more-tests/hash-code.rkt b/tests/more-tests/hash-code.rkt
index f7842d0..5265c76 100644
--- a/tests/more-tests/hash-code.rkt
+++ b/tests/more-tests/hash-code.rkt
@@ -46,14 +46,14 @@
 "structs"
 (define-struct thing (name age) #:mutable)
 (equal-hash-code (make-thing "danny" 32))
-(void (equal-hash-code (shared ([a (make-thing a a)]) a)))
+(equal-hash-code (shared ([a (make-thing a a)]) a))
 
-;; ;; symbols
-;; "symbols"
-;; (equal-hash-code 'hello)
-;; (equal-hash-code 'world)
+;; symbols
+"symbols"
+(equal-hash-code 'hello)
+(equal-hash-code 'world)
 
-;; ;; vectors
-;; "vectors"
-;; (equal-hash-code #(1 2 3 4 5))
-;; (equal-hash-code (shared ([v (vector 1 2 v 3 v)]) v))
+;; vectors
+"vectors"
+(equal-hash-code #(1 2 3 4 5))
+(equal-hash-code (shared ([v (vector 1 2 v 3 v)]) v))