hashCode calculation & caching for LazyTransformer

This uses the hashCode impl from ASeq.
LazyTransformer is its own ISeq, unlike LazySeq which delegates
to the collections realized from its thunks.

This caches hash and hasheq as well.

Signed-off-by: Stuart Halloway <stu@cognitect.com>

src/jvm/clojure/lang/LazyTransformer.java

@@ -15,6 +15,8 @@
 import java.util.*;
 
 public final class LazyTransformer extends Obj implements ISeq, Sequential, List, IPending, IHashEq{
+transient int _hash = -1;
+transient int _hasheq = -1;
 
 IStepper stepper;
 Object first = null;
@@ -210,14 +212,24 @@ public boolean equiv(Object o){
 	return ms == null;}
 
 public int hashCode(){
-	ISeq s = seq();
-	if(s == null)
-		return 1;
-	return Util.hash(seq());
+	if(_hash == -1)
+		{
+		int hash = 1;
+		for(ISeq s = seq(); s != null; s = s.next())
+			{
+			hash = 31 * hash + (s.first() == null ? 0 : s.first().hashCode());
+			}
+		this._hash = hash;
+		}
+	return _hash;
 }
 
 public int hasheq(){
-	return Murmur3.hashOrdered(this);
+	if(_hasheq == -1)
+		{
+		_hasheq  = Murmur3.hashOrdered(this);
+		}
+	return _hasheq;
 }
 
 public boolean equals(Object o){

test/clojure/test_clojure/data_structures.clj

@@ -1084,7 +1084,8 @@
                    (lazy-seq (cons :a
                      (lazy-seq (cons "7th" nil))))))
                  (into clojure.lang.PersistentQueue/EMPTY
-                       [-3 :a "7th"]) ]]
+                       [-3 :a "7th"])
+                 (sequence (map identity) [-3 :a "7th"]) ]]
     (doseq [c1 colls1, c2 colls1]
       (is-same-collection c1 c2)))
   (is-same-collection [-3 1 7] (vector-of :long -3 1 7)))