Merge pull request #1295 from braydonf/script-asm

Add script methods `fromASM()` and `toASM()`

lib/script/script.js

@@ -131,6 +131,48 @@ Script.prototype.toBuffer = function() {
   return bw.concat();
 };
 
+Script.fromASM = function(str) {
+  var script = new Script();
+  script.chunks = [];
+
+  var tokens = str.split(' ');
+  var i = 0;
+  while (i < tokens.length) {
+    var token = tokens[i];
+    var opcode = Opcode(token);
+    var opcodenum = opcode.toNumber();
+
+    if (_.isUndefined(opcodenum)) {
+      var buf = new Buffer(tokens[i], 'hex');
+      script.chunks.push({
+        buf: buf,
+        len: buf.length,
+        opcodenum: buf.length
+      });
+      i = i + 1;
+    } else if (opcodenum === Opcode.OP_PUSHDATA1 ||
+      opcodenum === Opcode.OP_PUSHDATA2 ||
+      opcodenum === Opcode.OP_PUSHDATA4) {
+      script.chunks.push({
+        buf: new Buffer(tokens[i + 2], 'hex'),
+        len: parseInt(tokens[i + 1]),
+        opcodenum: opcodenum
+      });
+      i = i + 3;
+    } else {
+      script.chunks.push({
+        opcodenum: opcodenum
+      });
+      i = i + 1;
+    }
+  }
+  return script;
+};
+
+Script.fromHex = function(str) {
+  return new Script(new buffer.Buffer(str, 'hex'));
+};
+
 Script.fromString = function(str) {
   if (JSUtil.isHexa(str) || str.length === 0) {
     return new Script(new buffer.Buffer(str, 'hex'));
@@ -179,8 +221,9 @@ Script.fromString = function(str) {
   return script;
 };
 
-Script.prototype._chunkToString = function(chunk) {
+Script.prototype._chunkToString = function(chunk, type) {
   var opcodenum = chunk.opcodenum;
+  var asm = (type === 'asm');
   var str = '';
   if (!chunk.buf) {
     // no data chunk
@@ -191,8 +234,12 @@ Script.prototype._chunkToString = function(chunk) {
       if (numstr.length % 2 !== 0) {
         numstr = '0' + numstr;
       }
+      if (asm) {
+        str = str + ' ' + numstr;
+      } else {
         str = str + ' ' + '0x' + numstr;
       }
+    }
   } else {
     // data chunk
     if (opcodenum === Opcode.OP_PUSHDATA1 ||
@@ -200,14 +247,27 @@ Script.prototype._chunkToString = function(chunk) {
       opcodenum === Opcode.OP_PUSHDATA4) {
       str = str + ' ' + Opcode(opcodenum).toString();
     }
-    str = str + ' ' + chunk.len;
     if (chunk.len > 0) {
-      str = str + ' ' + '0x' + chunk.buf.toString('hex');
+      if (asm) {
+        str = str + ' ' + chunk.buf.toString('hex');
+      } else {
+        str = str + ' ' + chunk.len + ' ' + '0x' + chunk.buf.toString('hex');
+      }
     }
   }
   return str;
 };
 
+Script.prototype.toASM = function() {
+  var str = '';
+  for (var i = 0; i < this.chunks.length; i++) {
+    var chunk = this.chunks[i];
+    str += this._chunkToString(chunk, 'asm');
+  }
+
+  return str.substr(1);
+};
+
 Script.prototype.toString = function() {
   var str = '';
   for (var i = 0; i < this.chunks.length; i++) {

test/script/script.js

@@ -159,6 +159,19 @@ describe('Script', function() {
 
   });
 
+  describe('#fromASM', function() {
+    it('should parse this known script in ASM', function() {
+      var asm = 'OP_DUP OP_HASH160 f4c03610e60ad15100929cc23da2f3a799af1725 OP_EQUALVERIFY OP_CHECKSIG';
+      var script = Script.fromASM(asm);
+      script.chunks[0].opcodenum.should.equal(Opcode.OP_DUP);
+      script.chunks[1].opcodenum.should.equal(Opcode.OP_HASH160);
+      script.chunks[2].opcodenum.should.equal(20);
+      script.chunks[2].buf.toString('hex').should.equal('f4c03610e60ad15100929cc23da2f3a799af1725');
+      script.chunks[3].opcodenum.should.equal(Opcode.OP_EQUALVERIFY);
+      script.chunks[4].opcodenum.should.equal(Opcode.OP_CHECKSIG);
+    });
+  });
+
   describe('#fromString', function() {
 
     it('should parse these known scripts', function() {
@@ -191,6 +204,11 @@ describe('Script', function() {
       script.toString().toString('hex').should.equal('OP_0 OP_PUSHDATA4 3 0x010203 OP_0');
     });
 
+    it('should output this known script as ASM', function() {
+      var script = Script.fromHex('76a914f4c03610e60ad15100929cc23da2f3a799af172588ac');
+      script.toASM().should.equal('OP_DUP OP_HASH160 f4c03610e60ad15100929cc23da2f3a799af1725 OP_EQUALVERIFY OP_CHECKSIG');
+    });
+
   });
 
   describe('toHex', function() {
@@ -463,7 +481,7 @@ describe('Script', function() {
     });
 
     it('should work for no data OP_RETURN', function() {
-      Script().add(Opcode.OP_RETURN).add(new Buffer('')).toString().should.equal('OP_RETURN 0');
+      Script().add(Opcode.OP_RETURN).add(new Buffer('')).toString().should.equal('OP_RETURN');
     });
     it('works with objects', function() {
       Script().add({
@@ -582,7 +600,7 @@ describe('Script', function() {
       var data = new Buffer('');
       var s = Script.buildDataOut(data);
       should.exist(s);
-      s.toString().should.equal('OP_RETURN 0');
+      s.toString().should.equal('OP_RETURN');
       s.isDataOut().should.equal(true);
     });
     it('should create script from some data', function() {