Script: add fromChunks and without

src/script.js

@@ -1,4 +1,5 @@
 var assert = require('assert')
+var bufferutils = require('./bufferutils')
 var crypto = require('./crypto')
 var opcodes = require('./opcodes')
 
@@ -367,4 +368,50 @@ Script.prototype.clone = function() {
   return new Script(this.buffer)
 }
 
+Script.fromChunks = function(chunks) {
+  assert(Array.isArray(chunks), 'Expected Array, got: ' + chunks)
+
+  var bufferSize = chunks.reduce(function(accum, chunk) {
+    var chunkSize = 1
+
+    // FIXME: transitionary
+    if (Array.isArray(chunk) || Buffer.isBuffer(chunk)) {
+      chunkSize = bufferutils.pushDataSize(chunk.length) + chunk.length
+    }
+
+    return accum + chunkSize
+  }, 0.0)
+
+  var buffer = new Buffer(bufferSize)
+  var offset = 0
+
+  chunks.forEach(function(chunk) {
+    // FIXME: transitionary
+    if (Array.isArray(chunk) || Buffer.isBuffer(chunk)) {
+      offset += bufferutils.writePushDataInt(buffer, chunk.length, offset)
+
+      // FIXME: transitionary
+//      chunk.copy(buffer, offset)
+      for (var i = 0; i < chunk.length; ++i) {
+        buffer[offset + i] = chunk[i]
+      }
+
+      offset += chunk.length
+
+    } else {
+      buffer.writeUInt8(chunk, offset)
+      offset += 1
+    }
+  })
+
+  return Script.fromBuffer(buffer)
+}
+
+// FIXME: doesn't work for data chunks, maybe time to use buffertools.compare...
+Script.prototype.without = function(needle) {
+  return Script.fromChunks(this.chunks.filter(function(op) {
+    return op !== needle
+  }))
+}
+
 module.exports = Script

test/script.js

@@ -1,6 +1,7 @@
 var assert = require('assert')
 var crypto = require('../src/crypto')
 var networks = require('../src/networks')
+var opcodes = require('../src/opcodes')
 
 var Address = require('../src/address')
 var ECPubKey = require('../src/ecpubkey')
@@ -156,4 +157,35 @@ describe('Script', function() {
       }, /Not enough signatures provided/)
     })
   })
+
+  describe('fromChunks', function() {
+    it('should match expected behaviour', function() {
+      var hash = new Buffer(32)
+      var script = Script.fromChunks([
+        opcodes.OP_HASH160,
+        hash,
+        opcodes.OP_EQUAL
+      ])
+
+      assert.deepEqual(script, Script.createP2SHScriptPubKey(hash))
+    })
+  })
+
+  describe('without', function() {
+    var hex = 'a914e8c300c87986efa94c37c0519929019ef86eb5b487'
+    var script = Script.fromHex(hex)
+
+    it('should return a script without the given value', function() {
+      var subScript = script.without(opcodes.OP_HASH160)
+
+      assert.equal(subScript.toHex(), '14e8c300c87986efa94c37c0519929019ef86eb5b487')
+    })
+
+    it('shouldnt mutate the original script', function() {
+      var subScript = script.without(opcodes.OP_EQUAL)
+
+      assert.notEqual(subScript.toHex(), hex)
+      assert.equal(script.toHex(), hex)
+    })
+  })
 })