Implement integer power method base on suggestions from #46

README.md

@@ -127,6 +127,12 @@ API
 * Long#**divide**/**div**(divisor: `Long | number | string`): `Long`<br />
   Returns this Long divided by the specified.
 
+* Long#**clone**(): `Long`<br />
+  Returns a deep copy of this Long.
+
+* Long#**power**/**pow**(exp: `Long | number | string`): `Long`<br />
+  Returns this Long to given integer power.
+
 * Long#**equals**/**eq**(other: `Long | number | string`): `boolean`<br />
   Tests if this Long's value equals the specified's.
 

externs/long.js

@@ -356,6 +356,23 @@ Long.prototype.divide = function(other) {};
  */
 Long.prototype.div = function(other) {};
 
+/**
+ * @return {!Long}
+ */
+Long.prototype.clone = function() {};
+
+/**
+ * @param {!Long|number|string} other
+ * @return {!Long}
+ */
+Long.prototype.power = function(other) {};
+
+/**
+ * @param {!Long|number|string} other
+ * @return {!Long}
+ */
+Long.prototype.pow = function(other) {};
+
 /**
  * @param {!Long|number|string} other
  * @return {!Long}

index.d.ts

@@ -136,6 +136,21 @@ declare class Long {
      */
     div(divisor: Long | number | string): Long;
 
+    /**
+     * Returns a deep copy of this Long.
+     */
+    clone(): Long;
+
+    /**
+     * Returns this Long to given integer power.
+     */
+    power(exp: Long | number | string): Long;
+
+    /**
+     * Returns this Long to given integer power.
+     */
+    pow(exp: Long | number | string): Long;
+
     /**
      * Tests if this Long's value equals the specified's.
      */

src/long.js

@@ -1086,6 +1086,42 @@ LongPrototype.modulo = function modulo(divisor) {
     return this.sub(this.div(divisor).mul(divisor));
 };
 
+/**
+ * Returns a deep copy of this Long.
+ * @this {!Long}
+ * @returns {!Long} Deep copy of this Long
+ */
+LongPrototype.clone = function clone() {
+    return new Long(this.low, this.high, this.unsigned);
+};
+
+/**
+ * Returns this Long to given integer power.
+ * @this {!Long}
+ * @param {!Long|number|string} exp Integer power
+ * @returns {!Long} This Long to given integer power
+ */
+LongPrototype.power = function power(exp) {
+    var a = this;
+    var b = Long.fromValue(exp);
+    if (b.isZero()) return Long.ONE.clone();
+    if (a.eq(Long.ONE) || b.eq(Long.ONE)) return a.clone();
+    if (b.isNegative()) return Long.ONE.div(a.pow(b.neg())); // being only integers, this will probably always be zero?
+    while (b.isEven()) {
+      b = b.shru(1);
+      a = a.mul(a);
+    }
+    return a.pow(b.sub(1)).mul(a);
+};
+
+/**
+ * Returns this Long to given integer power. This is an alias of {@link Long#power}.
+ * @function
+ * @param {!Long|number|string} exp Power
+ * @returns {!Long} This Long to given integer power
+ */
+LongPrototype.pow = LongPrototype.power;
+
 /**
  * Returns this Long modulo the specified. This is an alias of {@link Long#modulo}.
  * @function

tests/index.js

@@ -152,6 +152,19 @@ function testUnsignedMsbUnsigned() {
     assert.strictEqual(Long.fromString("9223372036854775808", true).toString(), "9223372036854775808");
 },
 
+function testPower() {
+    var a = Long.fromNumber(11);
+    var b = a.power(12);
+    var res = Long.fromNumber(3138428376721);
+    assert.deepEqual(b, res);
+    // check negative, which will probably always be zero since we can't store fractional result?
+    b = a.power(-3);
+    assert.deepEqual(b, Long.ZERO);
+    // except perhaps one which has a short circuit condition anyway?
+    b = Long.ONE.power(-1);
+    assert.deepEqual(b, Long.ONE);
+},
+
 function testIssue31() {
     var a = new Long(0, 8, true);
     var b = Long.fromNumber(2656901066, true);