Make ReadResultSet iterable [API-1315] (hazelcast#1399)

* Make ReadResultSet iterable [API-1315]
* Changes made according to comments on PR.[API-1315]

DOCUMENTATION.md

@@ -1917,6 +1917,13 @@ let value = await rb.readOne(sequence);
 console.log('Value:', value);
 value = await rb.readOne(sequence.add(1));
 console.log('Next value:', value);
+// Add some elements to the Ringbuffer
+await rb.addAll([300, 400, 500]);
+// We want to get 5 items from Ringbuffer and write to console.
+const items = await rb.readMany(0, 1, 5);
+for(const item of items){
+    console.log("Item:" item);
+}
 ```
 
 ### 8.4.8. Using Reliable Topic

src/core/ReadResultSet.ts

@@ -61,6 +61,13 @@ export interface ReadResultSet<T> {
      */
     size(): number;
 
+     /**
+     * Returns an iterator for elements in the list.
+     * 
+     * @returns the iterator for elements in the list.
+     */
+    [Symbol.iterator](): Iterator<T>; 
+
     /**
      * Returns the sequence of the item following the last read item. This
      * sequence can then be used to read items following the ones returned by

src/proxy/ringbuffer/LazyReadResultSet.ts

@@ -21,6 +21,32 @@ import {SerializationService, SerializationServiceV1} from '../../serialization/
 import {ReadResultSet} from '../../core';
 import {HazelcastSerializationError, SchemaNotFoundError} from './../../core/HazelcastError';
 
+
+
+/** @internal */
+class LazyReadResultSetIterator<T> implements Iterator<T> {
+
+    private index = 0;
+    private list: LazyReadResultSet<T>;
+
+    constructor(list: LazyReadResultSet<T>) {
+        this.list = list;
+    }
+
+    /**
+     * Returns the next element in the iteration.
+     * @throws {@link HazelcastSerializationError} if the next item is a compact object whose schema is not known
+     */
+    next(): IteratorResult<T> {
+        if (this.index < this.list.size()) {
+            return {done: false, value: this.list.get(this.index++)};
+        } else {
+            return {done: true, value: undefined};
+        }
+    }
+
+}
+
 /** @internal */
 export class LazyReadResultSet<T> implements ReadResultSet<T> {
 
@@ -80,4 +106,13 @@ export class LazyReadResultSet<T> implements ReadResultSet<T> {
         return this.nextSeq;
     }
 
+    values(): Iterator<T> {
+        return new LazyReadResultSetIterator(this);
+    }
+
+    [Symbol.iterator](): Iterator<T> {
+        return this.values();
+    }
+
+
 }

test/unit/ringbuffer/LazyReadResultSetTest.js

@@ -42,4 +42,14 @@ describe('LazyReadResultSetTest', function () {
         const set = new LazyReadResultSet(mockSerializationService, 4, [1, 2, 3, 4], [11, 12, 13, 14], 15);
         expect(set.get(4)).to.be.undefined;
     });
+
+    it('should be iterable', function () {
+        const set = new LazyReadResultSet(mockSerializationService, 4, [1, 2, 3, 4], [11, 12, 13, 14], 15);
+        let index = 0;
+        const values = [101, 102, 3, 4];
+        for (const item of set) {
+            expect(item).to.equal(values[index]);
+            index++;
+        }
+    });
 });