add Script#prepend()

lib/address.js

@@ -227,7 +227,7 @@ Address._transformString = function(data, network, type){
  *
  * Instantiate an address from a PublicKey instance
  *
- * @param {String} data - An instance of PublicKey
+ * @param {PublicKey} data - An instance of PublicKey
  * @param {String} network - The network: 'livenet' or 'testnet'
  * @returns {Address} A new valid and frozen instance of an Address
  */

lib/script.js

@@ -208,35 +208,66 @@ Script.prototype.isScriptHashIn = function() {
   });
 };
 
+/**
+ * Adds a script element at the start of the script.
+ * @param {*} obj a string, number, Opcode, Bufer, or object to add
+ * @returns {Script} this script instance
+ */
+Script.prototype.prepend = function(obj) {
+  this._addByType(obj, true);
+  return this;
+};
+
+/**
+ * Adds a script element to the end of the script.
+ *
+ * @param {*} obj a string, number, Opcode, Bufer, or object to add
+ * @returns {Script} this script instance
+ *
+ */
 Script.prototype.add = function(obj) {
+  this._addByType(obj, false);
+  return this;
+};
+
+Script.prototype._addByType = function(obj, prepend) {
   if (typeof obj === 'string') {
-    this._addOpcode(obj);
+    this._addOpcode(obj, prepend);
   } else if (typeof obj === 'number') {
-    this._addOpcode(obj);
+    this._addOpcode(obj, prepend);
   } else if (obj.constructor && obj.constructor.name && obj.constructor.name === 'Opcode') {
-    this._addOpcode(obj);
+    this._addOpcode(obj, prepend);
   } else if (Buffer.isBuffer(obj)) {
-    this._addBuffer(obj);
+    this._addBuffer(obj, prepend);
   } else if (typeof obj === 'object') {
-    this.chunks.push(obj);
+    this._insertAtPosition(obj, prepend);
   } else {
     throw new Error('Invalid script chunk');
   }
-  return this;
 };
 
-Script.prototype._addOpcode = function(opcode) {
+Script.prototype._insertAtPosition = function(op, prepend) {
+  if (prepend) {
+    this.chunks.unshift(op);
+  } else {
+    this.chunks.push(op);
+  }
+};
+
+Script.prototype._addOpcode = function(opcode, prepend) {
+  var op;
   if (typeof opcode === 'number') {
-    this.chunks.push(opcode);
+    op = opcode;
   } else if (opcode.constructor && opcode.constructor.name && opcode.constructor.name === 'Opcode') {
-    this.chunks.push(opcode.toNumber());
+    op = opcode.toNumber();
   } else {
-    this.chunks.push(Opcode(opcode).toNumber());
+    op = Opcode(opcode).toNumber();
   }
+  this._insertAtPosition(op, prepend);
   return this;
 };
 
-Script.prototype._addBuffer = function(buf) {
+Script.prototype._addBuffer = function(buf, prepend) {
   var opcodenum;
   var len = buf.length;
   if (buf.length > 0 && buf.length < Opcode.map.OP_PUSHDATA1) {
@@ -250,11 +281,11 @@ Script.prototype._addBuffer = function(buf) {
   } else {
     throw new Error('You can\'t push that much data');
   }
-  this.chunks.push({
+  this._insertAtPosition({
     buf: buf,
     len: len,
     opcodenum: opcodenum
-  });
+  }, prepend);
   return this;
 };
 

test/mocha.opts

@@ -0,0 +1 @@
+--recursive

test/script.js

@@ -251,37 +251,47 @@ describe('Script', function() {
 
   });
 
-  describe('#add', function() {
+  describe('#add and #prepend', function() {
 
     it('should add these ops', function() {
       Script().add('OP_CHECKMULTISIG').toString().should.equal('OP_CHECKMULTISIG');
+      Script().add('OP_1').add('OP_2').toString().should.equal('OP_1 OP_2');
+      Script().add(new Opcode('OP_CHECKMULTISIG')).toString().should.equal('OP_CHECKMULTISIG');
       Script().add(Opcode.map.OP_CHECKMULTISIG).toString().should.equal('OP_CHECKMULTISIG');
     });
 
-  });
+    it('should prepend these ops', function() {
+      Script().prepend('OP_CHECKMULTISIG').toString().should.equal('OP_CHECKMULTISIG');
+      Script().prepend('OP_1').prepend('OP_2').toString().should.equal('OP_2 OP_1');
+    });
 
-  it('should add these push data', function() {
-    var buf = new Buffer(1);
-    buf.fill(0);
-    Script().add(buf).toString().should.equal('1 0x00');
-    buf = new Buffer(255);
-    buf.fill(0);
-    Script().add(buf).toString().should.equal('OP_PUSHDATA1 255 0x' + buf.toString('hex'));
-    buf = new Buffer(256);
-    buf.fill(0);
-    Script().add(buf).toString().should.equal('OP_PUSHDATA2 256 0x' + buf.toString('hex'));
-    buf = new Buffer(Math.pow(2, 16));
-    buf.fill(0);
-    Script().add(buf).toString().should.equal('OP_PUSHDATA4 ' + Math.pow(2, 16) + ' 0x' + buf.toString('hex'));
-  });
+    it('should add and prepend correctly', function() {
+      Script().add('OP_1').prepend('OP_2').add('OP_3').prepend('OP_4').toString()
+        .should.equal('OP_4 OP_2 OP_1 OP_3');
+    });
 
-  it('should add both pushdata and non-pushdata chunks', function() {
-    Script().add('OP_CHECKMULTISIG').toString().should.equal('OP_CHECKMULTISIG');
-    Script().add(Opcode.map.OP_CHECKMULTISIG).toString().should.equal('OP_CHECKMULTISIG');
-    var buf = new Buffer(1);
-    buf.fill(0);
-    Script().add(buf).toString().should.equal('1 0x00');
-  });
+    it('should add these push data', function() {
+      var buf = new Buffer(1);
+      buf.fill(0);
+      Script().add(buf).toString().should.equal('1 0x00');
+      buf = new Buffer(255);
+      buf.fill(0);
+      Script().add(buf).toString().should.equal('OP_PUSHDATA1 255 0x' + buf.toString('hex'));
+      buf = new Buffer(256);
+      buf.fill(0);
+      Script().add(buf).toString().should.equal('OP_PUSHDATA2 256 0x' + buf.toString('hex'));
+      buf = new Buffer(Math.pow(2, 16));
+      buf.fill(0);
+      Script().add(buf).toString().should.equal('OP_PUSHDATA4 ' + Math.pow(2, 16) + ' 0x' + buf.toString('hex'));
+    });
 
+    it('should add both pushdata and non-pushdata chunks', function() {
+      Script().add('OP_CHECKMULTISIG').toString().should.equal('OP_CHECKMULTISIG');
+      Script().add(Opcode.map.OP_CHECKMULTISIG).toString().should.equal('OP_CHECKMULTISIG');
+      var buf = new Buffer(1);
+      buf.fill(0);
+      Script().add(buf).toString().should.equal('1 0x00');
+    });
+  });
 
 });