CLJ-1082 - add generic ranged iterator for use by SubVectors and a fallback for cases where it cannot be applied

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

Author: mikera

src/jvm/clojure/lang/APersistentVector.java

@@ -241,6 +241,24 @@ public void add(Object o){
 	};
 }
 
+Iterator rangedIterator(final int start, final int end){
+	return new Iterator(){
+		int i = start;
+
+		public boolean hasNext(){
+			return i < end;
+		}
+
+		public Object next(){
+			return nth(i++);
+		}
+
+		public void remove(){
+			throw new UnsupportedOperationException();
+		}
+	};
+}
+
 public List subList(int fromIndex, int toIndex){
 	return (List) RT.subvec(this, fromIndex, toIndex);
 }
@@ -524,7 +542,12 @@ public SubVector(IPersistentMap meta, IPersistentVector v, int start, int end){
 		this.end = end;
 	}
 
-	public Iterator iterator(){return ((PersistentVector)v).rangedIterator(start,end);}
+	public Iterator iterator(){
+		if (v instanceof APersistentVector) {
+			return ((APersistentVector)v).rangedIterator(start,end);
+		}
+		return super.iterator();
+	}
 
 	public Object nth(int i){
 		if((start + i >= end) || (i < 0))

src/jvm/clojure/lang/PersistentVector.java

@@ -233,6 +233,7 @@ public ISeq seq(){
 	return chunkedSeq();
 }
 
+@Override
 Iterator rangedIterator(final int start, final int end){
 	return new Iterator(){
 		int i = start;

test/clojure/test_clojure/vectors.clj

@@ -79,6 +79,11 @@
            vs-32 vs
            vs nil))))
 
+(deftest test-primitive-subvector-reduce
+  ;; regression test for CLJ-1082
+  (is (== 60 (let [prim-vec (into (vector-of :long) (range 1000))]
+               (reduce + (subvec prim-vec 10 15))))))
+
 (deftest test-vec-compare
   (let [nums      (range 1 100)
         ; randomly replaces a single item with the given value