From eb03993c6d43fe6f8db280fbcd05c61aeb11f713 Mon Sep 17 00:00:00 2001
From: Gav Wood <gav@ethcore.io>
Date: Mon, 11 Jan 2016 13:52:40 +0100
Subject: [PATCH] Transaction struct improvements.

---
 src/transaction.rs | 48 +++++++++++++++++++++-------------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/src/transaction.rs b/src/transaction.rs
index d13a728bb..f162bb2c5 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -1,37 +1,33 @@
 use util::*;
 
+pub enum Action {
+	Create,
+	Call(Address),
+}
+
 /// A set of information describing an externally-originating message call
 /// or contract creation operation.
 pub struct Transaction {
 	nonce: U256,
 	gas_price: U256,
 	gas: U256,
-	to: Option<Address>,
+	action: Action,
 	value: U256,
 	data: Bytes,
 
 	hash: RefCell<Option<H256>>, //TODO: make this private
 }
 
-impl Transaction {
-	/// Is this transaction meant to create a contract?
-	pub fn is_contract_creation(&self) -> bool {
-		self.to.is_none()
-	}
-
-	/// Is this transaction meant to send a message?
-	pub fn is_message_call(&self) -> bool {
-		!self.is_contract_creation()
-	}
-}
-
 impl RlpStandard for Transaction {
 	fn rlp_append(&self, s: &mut RlpStream) {
 		s.append_list(6);
 		s.append(&self.nonce);
 		s.append(&self.gas_price);
 		s.append(&self.gas);
-		s.append(&self.to);
+		match self.action {
+			Action::Create => s.append_empty_data(),
+			Action::Call(ref to) => s.append(to),
+		};
 		s.append(&self.value);
 		s.append(&self.data);
 	}
@@ -54,18 +50,19 @@ impl Transaction {
 	pub fn note_dirty(&self) {
  		*self.hash.borrow_mut() = None;
 	}
+
+	/// Returns transaction type.
+	pub fn action(&self) -> &Action { &self.action }
 }
 
-impl Encodable for Transaction {
-	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
-		encoder.emit_list(| e | {
-			self.nonce.encode(e);
-			self.gas_price.encode(e);
-			self.gas.encode(e);
-			self.to.encode(e);
-			self.value.encode(e);
-			self.data.encode(e);
-		})
+impl Decodable for Action {
+	fn decode<D>(decoder: &D) -> Result<Self, DecoderError> where D: Decoder {
+		let rlp = decoder.as_rlp();
+		if rlp.is_empty() {
+			Ok(Action::Create)
+		} else {
+			Ok(Action::Call(try!(rlp.as_val())))
+		}
 	}
 }
 
@@ -77,7 +74,7 @@ impl Decodable for Transaction {
 			nonce: try!(Decodable::decode(&d[0])),
 			gas_price: try!(Decodable::decode(&d[1])),
 			gas: try!(Decodable::decode(&d[2])),
-			to: try!(Decodable::decode(&d[3])),
+			action: try!(Decodable::decode(&d[3])),
 			value: try!(Decodable::decode(&d[4])),
 			data: try!(Decodable::decode(&d[5])),
 			hash: RefCell::new(None)
@@ -86,4 +83,3 @@ impl Decodable for Transaction {
 		Ok(transaction)
 	}
 }
-