opcode refactor: isSmallIntOp

lib/opcode.js

@@ -1,8 +1,9 @@
 'use strict';
 
 function Opcode(num) {
-  if (!(this instanceof Opcode))
+  if (!(this instanceof Opcode)) {
     return new Opcode(num);
+  }
 
   if (typeof num === 'number') {
     this.num = num;
@@ -39,8 +40,9 @@ Opcode.prototype.fromString = function(str) {
 
 Opcode.prototype.toString = function() {
   var str = Opcode.reverseMap[this.num];
-  if (typeof str === 'undefined')
+  if (typeof str === 'undefined') {
     throw new Error('Opcode does not have a string representation');
+  }
   return str;
 };
 
@@ -191,4 +193,15 @@ for (var k in Opcode.map) {
   }
 }
 
+/**
+ * @returns true if opcode is one of OP_0, OP_1, ..., OP_16
+ */
+Opcode.isSmallIntOp = function(opcode) {
+  if (opcode instanceof Opcode) {
+    opcode = opcode.toNumber();
+  }
+  return ((opcode === Opcode.map.OP_0) ||
+    ((opcode >= Opcode.map.OP_1) && (opcode <= Opcode.map.OP_16)));
+};
+
 module.exports = Opcode;

test/opcode.js

@@ -72,5 +72,43 @@ describe('Opcode', function() {
     });
 
   });
+  var smallints = [
+    Opcode('OP_0'),
+    Opcode('OP_1'),
+    Opcode('OP_2'),
+    Opcode('OP_3'),
+    Opcode('OP_4'),
+    Opcode('OP_5'),
+    Opcode('OP_6'),
+    Opcode('OP_7'),
+    Opcode('OP_8'),
+    Opcode('OP_9'),
+    Opcode('OP_10'),
+    Opcode('OP_11'),
+    Opcode('OP_12'),
+    Opcode('OP_13'),
+    Opcode('OP_14'),
+    Opcode('OP_15'),
+    Opcode('OP_16')
+  ];
+
+  describe('@isSmallIntOp', function() {
+    var testSmallInt = function() {
+      Opcode.isSmallIntOp(this).should.equal(true);
+    };
+    for (var i = 0; i < smallints.length; i++) {
+      var op = smallints[i];
+      it('should work for small int ' + op, testSmallInt.bind(op));
+    }
+
+    it('should work for non-small ints', function() {
+      Opcode.isSmallIntOp(Opcode('OP_RETURN')).should.equal(false);
+      Opcode.isSmallIntOp(Opcode('OP_CHECKSIG')).should.equal(false);
+      Opcode.isSmallIntOp(Opcode('OP_IF')).should.equal(false);
+      Opcode.isSmallIntOp(Opcode('OP_NOP')).should.equal(false);
+    });
+
+  });
+
 
 });