clean up comments & extract methods

[follow-up #125]

src/script.js

@@ -104,72 +104,74 @@ Script.prototype.parse = function() {
  * templates and return a string naming the detected type.
  *
  * Currently supported are:
- * Pubkeyhash
+ * Pubkeyhash (address)
  *   Paying to a Bitcoin address which is the hash of a pubkey.
  *   OP_DUP OP_HASH160 [pubKeyHash] OP_EQUALVERIFY OP_CHECKSIG
- *   Example:
  *
- * Pubkey:
+ * Pubkey
  *   Paying to a public key directly.
  *   [pubKey] OP_CHECKSIG
- *   Example: txid 0e3e2357e806b6cdb1f70b54c3a3a17b6714ee1f0e68bebb44a74b1efd512098
  *
  * Scripthash (P2SH)
  *    Paying to an address which is the hash of a script
  *    OP_HASH160 [Scripthash] OP_EQUAL
- *    Example:
  *
  * Multisig
  *    Paying to multiple pubkeys and require a number of the signatures
  *    m [pubkey] [pubkey] [pubkey] n OP_CHECKMULTISIG
- *    Example:
  *
- * Strange:
+ * Nulldata
+ *    Provably prune-able outputs
+ *    OP_RETURN [data]
+ *
+ * Nonstandard:
  *   Any other script (no template matched).
+ *
+ * https://github.com/bitcoin/bitcoin/blob/19e5b9d2dfcac4efadba636745485d9660fb1abe/src/script.cpp#L75
  */
 
-// Below is the current standard set of out types
-/* const char* GetTxnOutputType(txnouttype t)
-{
-    switch (t)
-    {
-    case TX_NONSTANDARD: return "nonstandard";
-    case TX_PUBKEY: return "pubkey";
-    case TX_PUBKEYHASH: return "pubkeyhash";
-    case TX_SCRIPTHASH: return "scripthash";
-    case TX_MULTISIG: return "multisig";
-    case TX_NULL_DATA: return "nulldata";
-    }
-    return NULL;
-}*/
-
-// https://github.com/bitcoin/bitcoin/blob/19e5b9d2dfcac4efadba636745485d9660fb1abe/src/script.cpp#L75
-
-// supporting tx_null_data https://github.com/bitcoin/bitcoin/pull/3128
-// https://helloblock.io/mainnet/transactions/ebc9fa1196a59e192352d76c0f6e73167046b9d37b8302b6bb6968dfd279b767
 Script.prototype.getOutType = function() {
-  if (this.chunks.length == 5 &&
+  if (isPubkeyhash.call(this)) {
+    return 'pubkeyhash'
+  } else if (isPubkey.call(this)) {
+    return 'pubkey'
+  } else if (isScripthash.call(this)) {
+    return 'scripthash'
+  } else if (isMultisig.call(this)) {
+    return 'multisig'
+  } else if (isNulldata.call(this)) {
+    return 'nulldata'
+  } else {
+    return 'nonstandard'
+  }
+}
+
+function isPubkeyhash() {
+  return this.chunks.length == 5 &&
     this.chunks[0] == Opcode.map.OP_DUP &&
     this.chunks[1] == Opcode.map.OP_HASH160 &&
     Array.isArray(this.chunks[2]) &&
     this.chunks[2].length === 20 &&
     this.chunks[3] == Opcode.map.OP_EQUALVERIFY &&
-    this.chunks[4] == Opcode.map.OP_CHECKSIG) {
-    // Transfer to Bitcoin address
-    return 'pubkeyhash';
-  } else if (this.chunks.length === 2 &&
+    this.chunks[4] == Opcode.map.OP_CHECKSIG
+}
+
+function isPubkey() {
+  return this.chunks.length === 2 &&
     Array.isArray(this.chunks[0]) &&
-    this.chunks[1] === Opcode.map.OP_CHECKSIG) {
-    // [pubkey] OP_CHECKSIG
-    return 'pubkey';
-  } else if (this.chunks[this.chunks.length - 1] == Opcode.map.OP_EQUAL &&
+    this.chunks[1] === Opcode.map.OP_CHECKSIG
+}
+
+function isScripthash() {
+  return this.chunks[this.chunks.length - 1] == Opcode.map.OP_EQUAL &&
     this.chunks[0] == Opcode.map.OP_HASH160 &&
     Array.isArray(this.chunks[1]) &&
     this.chunks[1].length === 20 &&
-    this.chunks.length == 3) {
-    // Transfer to M-OF-N
-    return 'scripthash';
-  } else if (this.chunks.length > 3 &&
+    this.chunks.length == 3
+}
+
+function isMultisig() {
+  return this.chunks.length > 3 &&
     // m is a smallint
     isSmallIntOp(this.chunks[0]) &&
     // n is a smallint
@@ -181,32 +183,28 @@ Script.prototype.getOutType = function() {
     // n is the size of chunk length minus 3 (m, n, OP_CHECKMULTISIG)
     this.chunks.length - 3 === this.chunks[this.chunks.length - 2] - Opcode.map.OP_RESERVED &&
     // last chunk is OP_CHECKMULTISIG
-    this.chunks[this.chunks.length - 1] == Opcode.map.OP_CHECKMULTISIG) {
-    return 'multisig'
-  } else if (this.chunks[0] === Opcode.map.OP_RETURN) {
-    return 'nulldata'
-  } else {
-    return 'nonstandard';
-  }
+    this.chunks[this.chunks.length - 1] == Opcode.map.OP_CHECKMULTISIG
+}
+
+function isNulldata() {
+  return this.chunks[0] === Opcode.map.OP_RETURN
 }
 
 function isSmallIntOp(opcode) {
   return ((opcode == Opcode.map.OP_0) ||
-    ((opcode >= Opcode.map.OP_1) && (opcode <= Opcode.map.OP_16)));
-};
+    ((opcode >= Opcode.map.OP_1) && (opcode <= Opcode.map.OP_16)))
+}
 
 /**
  * Returns the address corresponding to this output in hash160 form.
  * Assumes strange scripts are P2SH
  */
 Script.prototype.toScriptHash = function() {
-  var outType = this.getOutType()
-
-  if (outType == 'pubkeyhash') {
+  if(isPubkeyhash.call(this)) {
     return this.chunks[2]
   }
 
-  if (outType == 'scripthash') {
+  if(isScripthash.call(this)) {
     return crypto.hash160(this.buffer)
   }
 
@@ -215,13 +213,11 @@ Script.prototype.toScriptHash = function() {
 
 //TODO: support testnet
 Script.prototype.getToAddress = function() {
-  var outType = this.getOutType()
-
-  if (outType == 'pubkeyhash') {
+  if(isPubkeyhash.call(this)) {
     return new Address(this.chunks[2])
   }
 
-  if (outType == 'scripthash') {
+  if(isScripthash.call(this)) {
     return new Address(this.chunks[1], 5)
   }
 
@@ -255,7 +251,7 @@ Script.prototype.getFromAddress = function(){
  * Multisig:
  *   Paying to M-of-N public keys.
  *
- * Strange:
+ * Nonstandard:
  *   Any other script (no template matched).
  */
 Script.prototype.getInType = function() {
@@ -263,20 +259,20 @@ Script.prototype.getInType = function() {
     Array.isArray(this.chunks[0])) {
     // Direct IP to IP transactions only have the signature in their scriptSig.
     // TODO: We could also check that the length of the data is correct.
-    return 'pubkey';
+    return 'pubkey'
   } else if (this.chunks.length == 2 &&
     Array.isArray(this.chunks[0]) &&
     Array.isArray(this.chunks[1])) {
-    return 'pubkeyhash';
+    return 'pubkeyhash'
   } else if (this.chunks[0] == Opcode.map.OP_0 &&
     this.chunks.slice(1).reduce(function(t, chunk, i) {
-      return t && Array.isArray(chunk) && (chunk[0] == 48 || i == this.chunks.length - 1);
+      return t && Array.isArray(chunk) && (chunk[0] == 48 || i == this.chunks.length - 1)
     }, true)) {
-    return 'multisig';
+    return 'multisig'
   } else {
-    return 'nonstandard';
+    return 'nonstandard'
   }
-};
+}
 
 /**
  * Returns the affected public key for this input.