chain: refactor coins.

lib/blockchain/coins.js

@@ -317,8 +317,9 @@ Coins.prototype.toRaw = function toRaw(writer) {
 
 Coins.prototype.fromRaw = function fromRaw(data, hash, index) {
   var p = new BufferReader(data);
-  var i = 0;
-  var bits, coin, offset, size, fstart, flen, bit, oct, spent;
+  var pos = 0;
+  var fstart, flen, bit, oct;
+  var bits, coin, spent;
 
   this.version = p.readVarint();
 
@@ -339,72 +340,25 @@ Coins.prototype.fromRaw = function fromRaw(data, hash, index) {
 
   while (p.left()) {
     // Read a single bit out of the spent field.
-    bit = i % 8;
-    oct = (i - bit) / 8;
+    bit = pos % 8;
+    oct = (pos - bit) / 8;
     spent = (p.data[fstart + oct] >>> (7 - bit)) & 1;
 
     // Already spent.
     if (spent) {
-      // Don't bother pushing outputs on if
-      // we're seeking to a specific index.
-      if (index != null) {
-        if (i === index)
-          return;
-        i++;
-        continue;
-      }
-
       this.outputs.push(null);
-      i++;
-      continue;
-    }
-
-    offset = p.offset;
-
-    // Skip past the compressed scripts.
-    switch (p.readU8()) {
-      case 0:
-        p.seek(p.readVarint());
-        break;
-      case 1:
-      case 2:
-        p.seek(20);
-        break;
-      case 3:
-        p.seek(33);
-        break;
-      default:
-        throw new Error('Bad prefix.');
-    }
-
-    // Skip past the value.
-    p.readVarint();
-
-    size = p.offset - offset;
-
-    // Keep going if we're seeking
-    // to a specific index.
-    if (index != null && i !== index) {
-      i++;
+      pos++;
       continue;
     }
 
     // Store the offset and size
     // in the compressed coin object.
-    coin = new CompressedCoin(offset, size, data);
-
-    // We found our coin.
-    if (index != null)
-      return coin.toCoin(this, i);
+    coin = CompressedCoin.fromRaw(p);
 
     this.outputs.push(coin);
-    i++;
+    pos++;
   }
 
-  // We couldn't find our coin.
-  if (index != null)
-    return;
-
   return this;
 };
 
@@ -417,8 +371,56 @@ Coins.prototype.fromRaw = function fromRaw(data, hash, index) {
  */
 
 Coins.parseCoin = function parseCoin(data, hash, index) {
-  assert(index != null, 'Bad coin index.');
-  return new Coins().fromRaw(data, hash, index);
+  var p = new BufferReader(data);
+  var coin = new Coin();
+  var pos = 0;
+  var fstart, flen, bit, oct;
+  var spent, bits;
+
+  coin.version = p.readVarint();
+
+  bits = p.readU32();
+
+  coin.hash = hash;
+  coin.index = index;
+  coin.height = bits >>> 1;
+  coin.hash = hash;
+  coin.coinbase = (bits & 1) !== 0;
+
+  if (coin.height === 0x7fffffff)
+    coin.height = -1;
+
+  // Mark the start of the spent field and
+  // seek past it to avoid reading a buffer.
+  flen = p.readVarint();
+  fstart = p.offset;
+  p.seek(flen);
+
+  while (p.left()) {
+    // Read a single bit out of the spent field.
+    bit = pos % 8;
+    oct = (pos - bit) / 8;
+    spent = (p.data[fstart + oct] >>> (7 - bit)) & 1;
+
+    // We found our coin.
+    if (pos === index) {
+      if (spent)
+        return;
+      decompress.script(p, coin.script);
+      coin.value = p.readVarint();
+      return coin;
+    }
+
+    // Already spent.
+    if (spent) {
+      pos++;
+      continue;
+    }
+
+    // Skip passed the compressed coin.
+    skipCoin(p);
+    pos++;
+  }
 };
 
 /**
@@ -439,7 +441,7 @@ Coins.fromRaw = function fromRaw(data, hash) {
  */
 
 Coins.prototype.fromTX = function fromTX(tx) {
-  var i;
+  var i, output;
 
   this.version = tx.version;
   this.hash = tx.hash('hex');
@@ -447,10 +449,13 @@ Coins.prototype.fromTX = function fromTX(tx) {
   this.coinbase = tx.isCoinbase();
 
   for (i = 0; i < tx.outputs.length; i++) {
-    if (tx.outputs[i].script.isUnspendable()) {
+    output = tx.outputs[i];
+
+    if (output.script.isUnspendable()) {
       this.outputs.push(null);
       continue;
     }
+
     this.outputs.push(Coin.fromTX(tx, i));
   }
 
@@ -487,9 +492,6 @@ Coins.fromTX = function fromTX(tx) {
  */
 
 function CompressedCoin(offset, size, raw) {
-  if (!(this instanceof CompressedCoin))
-    return new CompressedCoin(offset, size, raw);
-
   this.offset = offset;
   this.size = size;
   this.raw = raw;
@@ -534,6 +536,47 @@ CompressedCoin.prototype.toRaw = function toRaw() {
   return this.raw.slice(this.offset, this.offset + this.size);
 };
 
+/**
+ * Instantiate compressed coin from reader.
+ * @param {BufferReader} p
+ * @returns {CompressedCoin}
+ */
+
+CompressedCoin.fromRaw = function fromRaw(p) {
+  var offset = p.offset;
+  var size = skipCoin(p);
+  return new CompressedCoin(offset, size, p.data);
+};
+
+/*
+ * Helpers
+ */
+
+function skipCoin(p) {
+  var start = p.offset;
+
+  // Skip past the compressed scripts.
+  switch (p.readU8()) {
+    case 0:
+      p.seek(p.readVarint());
+      break;
+    case 1:
+    case 2:
+      p.seek(20);
+      break;
+    case 3:
+      p.seek(33);
+      break;
+    default:
+      throw new Error('Bad prefix.');
+  }
+
+  // Skip past the value.
+  p.readVarint();
+
+  return p.offset - start;
+}
+
 /*
  * Expose
  */