From 1d7ed3b2c3a91ee9f07342fe71f4a28d0748dc18 Mon Sep 17 00:00:00 2001
From: Andrei Maiboroda <andrei@ethereum.org>
Date: Fri, 28 Apr 2017 18:02:07 +0200
Subject: [PATCH] Style polishing & comments improvement

---
 libethereum/Block.h       |  3 ++-
 libethereum/Executive.cpp | 29 ++++++++++++++++++++---------
 libethereum/State.h       |  2 ++
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/libethereum/Block.h b/libethereum/Block.h
index c6d827aadfd..868aa8c45e0 100644
--- a/libethereum/Block.h
+++ b/libethereum/Block.h
@@ -202,9 +202,10 @@ class Block
 	/// Get the bloom filter of a particular transaction that happened in the block.
 	LogBloom const& logBloom(unsigned _i) const { return receipt(_i).bloom(); }
 
-	/// Get the State root hash immediately after the given number of pending transactions have been applied.
+	/// Get the State root hash immediately before after all previous transactions before transaction @a _i have been applied.
 	/// If (_i == 0) returns the initial state of the block.
 	/// If (_i == pending().size()) returns the final state of the block, prior to rewards.
+	/// Returns zero hash if intermediate state root is not available in the receipt (the case after EIP98)
 	h256 stateRootBeforeTx(unsigned _i) const;
 
 	// State-change operations
diff --git a/libethereum/Executive.cpp b/libethereum/Executive.cpp
index 4871d9c95d0..c15078478b0 100644
--- a/libethereum/Executive.cpp
+++ b/libethereum/Executive.cpp
@@ -141,6 +141,25 @@ string StandardTrace::json(bool _styled) const
 	return _styled ? Json::StyledWriter().write(m_trace) : Json::FastWriter().write(m_trace);
 }
 
+namespace
+{
+
+State& initIntermediateState(State& _s, Block const& _block, unsigned _txIndex, BlockChain const& _bc)
+{
+	_s = _block.state();
+	u256 const rootHash = _block.stateRootBeforeTx(_txIndex);
+	if (rootHash)
+		_s.setRoot(rootHash);
+	else
+	{
+		_s.setRoot(_block.stateRootBeforeTx(0));
+		_s.executeBlockTransactions(_block, _txIndex, _bc.lastHashes(_block.info().parentHash()), *_bc.sealEngine());
+	}
+	return _s;
+}
+
+}
+
 Executive::Executive(Block& _s, BlockChain const& _bc, unsigned _level):
 	m_s(_s.mutableState()),
 	m_envInfo(_s.info(), _bc.lastHashes(_s.info().parentHash())),
@@ -158,19 +177,11 @@ Executive::Executive(Block& _s, LastHashes const& _lh, unsigned _level):
 }
 
 Executive::Executive(State& _s, Block const& _block, unsigned _txIndex, BlockChain const& _bc, unsigned _level):
-	m_s(_s = _block.state()),
+	m_s(initIntermediateState(_s, _block, _txIndex, _bc)),
 	m_envInfo(_block.info(), _bc.lastHashes(_block.info().parentHash()), _txIndex ? _block.receipt(_txIndex - 1).gasUsed() : 0),
 	m_depth(_level),
 	m_sealEngine(*_bc.sealEngine())
 {
-	u256 const rootHash = _block.stateRootBeforeTx(_txIndex);
-	if (rootHash)
-		m_s.setRoot(rootHash);
-	else
-	{
-		m_s.setRoot(_block.stateRootBeforeTx(0));
-		m_s.executeBlockTransactions(_block, _txIndex, _bc.lastHashes(_block.info().parentHash()), *_bc.sealEngine());
-	}
 }
 
 u256 Executive::gasUsed() const
diff --git a/libethereum/State.h b/libethereum/State.h
index 2ef4760c878..9a69aa6be6f 100644
--- a/libethereum/State.h
+++ b/libethereum/State.h
@@ -207,6 +207,8 @@ class State
 	/// This will change the state accordingly.
 	std::pair<ExecutionResult, TransactionReceipt> execute(EnvInfo const& _envInfo, SealEngineFace const& _sealEngine, Transaction const& _t, Permanence _p = Permanence::Committed, OnOpFunc const& _onOp = OnOpFunc());
 
+	/// Execute @a _txCount transactions of a given block.
+	/// This will change the state accordingly.
 	void executeBlockTransactions(Block const& _block, unsigned _txCount, LastHashes const& _lastHashes, SealEngineFace const& _sealEngine);
 
 	/// Check if the address is in use.