add metod filterdTxsHash to MerkleBlock, that return all the txs hash in the block that match the filter (depth === 0 and flag bit is 1)

lib/block/merkleblock.js

@@ -8,6 +8,7 @@ var BufferWriter = require('../encoding/bufferwriter');
 var Hash = require('../crypto/hash');
 var JSUtil = require('../util/js');
 var Transaction = require('../transaction');
+var errors = require('../errors');
 var $ = require('../util/preconditions');
 
 /**
@@ -63,6 +64,7 @@ function MerkleBlock(arg) {
   _.extend(this,info);
   this._flagBitsUsed = 0;
   this._hashesUsed = 0;
+
   return this;
 }
 
@@ -149,19 +151,48 @@ MerkleBlock.prototype.validMerkleTree = function validMerkleTree() {
   return BufferUtil.equals(root, this.header.merkleRoot);
 };
 
+/**
+ * Return a list of all the txs hash that match the filter
+ * @returns {Array} - txs hash that match the filter
+ */
+MerkleBlock.prototype.filterdTxsHash = function validMerkleTree() {
+  $.checkState(_.isArray(this.flags), 'MerkleBlock flags is not an array');
+  $.checkState(_.isArray(this.hashes), 'MerkleBlock hashes is not an array');
+
+  // Can't have more hashes than numTransactions
+  if(this.hashes.length > this.numTransactions) {
+    throw new errors.MerkleBlock.InvalidMerkleTree();
+  }
+
+  // Can't have more flag bits than num hashes
+  if(this.flags.length * 8 < this.hashes.length) {
+    throw new errors.MerkleBlock.InvalidMerkleTree();
+  }
+
+  var height = this._calcTreeHeight();
+  var opts = { hashesUsed: 0, flagBitsUsed: 0 };
+  var txs = this._traverseMerkleTree(height, 0, opts, true);
+  if(opts.hashesUsed !== this.hashes.length) {
+    throw new errors.MerkleBlock.InvalidMerkleTree();
+  }
+  return txs;
+};
+
 /**
  * Traverse a the tree in this MerkleBlock, validating it along the way
  * Modeled after Bitcoin Core merkleblock.cpp TraverseAndExtract()
  * @param {Number} - depth - Current height
  * @param {Number} - pos - Current position in the tree
  * @param {Object} - opts - Object with values that need to be mutated throughout the traversal
+ * @param {Boolean} - checkForTxs - if true return opts.txs else return the Merkle Hash
  * @param {Number} - opts.flagBitsUsed - Number of flag bits used, should start at 0
  * @param {Number} - opts.hashesUsed - Number of hashes used, should start at 0
- * @param {Array} - opts.txs - Will finish populated by transactions found during traversal
+ * @param {Array} - opts.txs - Will finish populated by transactions found during traversal that match the filter
  * @returns {Buffer|null} - Buffer containing the Merkle Hash for that height
+ * @returns {Array} - transactions found during traversal that match the filter
  * @private
  */
-MerkleBlock.prototype._traverseMerkleTree = function traverseMerkleTree(depth, pos, opts) {
+MerkleBlock.prototype._traverseMerkleTree = function traverseMerkleTree(depth, pos, opts, checkForTxs) {
   /* jshint maxcomplexity:  12*/
   /* jshint maxstatements: 20 */
 
@@ -169,6 +200,7 @@ MerkleBlock.prototype._traverseMerkleTree = function traverseMerkleTree(depth, p
   opts.txs = opts.txs || [];
   opts.flagBitsUsed = opts.flagBitsUsed || 0;
   opts.hashesUsed = opts.hashesUsed || 0;
+  var checkForTxs = checkForTxs || false;
 
   if(opts.flagBitsUsed > this.flags.length * 8) {
     return null;
@@ -189,7 +221,11 @@ MerkleBlock.prototype._traverseMerkleTree = function traverseMerkleTree(depth, p
     if(pos*2+1 < this._calcTreeWidth(depth-1)) {
       right = this._traverseMerkleTree(depth-1, pos*2+1, opts);
     }
+    if (checkForTxs){
+      return opts.txs;
+    } else {
       return Hash.sha256sha256(new Buffer.concat([left, right]));
+    };
   }
 };