Psuedo ActionEvaluator

ActionEvaluator.cs

IEnumerable<ActionEvaluation> EvaluateBlock(IPreEvaluationBlock block, IAccountStateDelta prevState)
{
	UInt256 remainingGasPerBlock = block.GasLimit();
	IEnumerable<ActionEvaluation> evaluations 
		= ExecuteActions(_beginBlockActions, prevState, remainingGasPerBlock, 0);
  	foreach(ActionEvaluation eval in evaluations)
	{
		yield return eval;
		prevState = eval.OutputState.UseGas(0);
	}

	foreach(ITransaction tx in block.Transactions)
	{
		evaluations = ExecuteTx(tx, prevState, remainingGasPerBlock);
		foreach(ActionEvaluation eval in evaluations)
		{
			yield return eval;
			prevState = eval.OutputState;
		}
		UInt256 usedGas = evaluations.Select(x => x.OutputStates.GasUsed).Sum();
		remainingGasPerBlock -= usedGas;
	}

	evaluations = ExecuteActions(_endBlockActions, prevState, remainingGasPerBlock, 0);
	foreach(ActionEvaluation eval in evaluations)
	{
		yield return eval;
		prevState = eval.OutputState;
	}
} 

IEnumerable<ActionEvaluation> EvaluateTx(ITransaction tx, IAccountStateDelta prevState, UInt256 gasLimit, FungibleAssetValue baseGasPrice)
{
	UInt256 gasLimitPerTransaction = tx.GasLimit();
	if(gasLimit < gasLimitPerTransaction) throw InvalidTransaction();
	
	FungibleAssetValue commissionGasPrice = Min(tx.CommissionGasPrice(), tx.MaxGasPrice() - baseGasPrice);
	FungibleAssetValue gasPrice = commissionGasPrice + baseGasPrice;
	
	return EvaluateActions(tx.Actions, prevState, gasLimitPerTransaction, gasPrice);
}

IEnumerable<ActionEvaluation> EvaluateActions(IImmutableList<IAction> actions, IAccountStateDelta prevState, UInt256 gasLimit, FungibleAssetValue commissionGasPrice, FungibleAssetValue gasPrice)
{
	foreach(IAction action in actions)
	{
		// Burn reserve fee first for prevent collect minus fee
		FungibleAssetValue reserveFee = gasPrice * gasLimit;
		IAccountStateDelta nextState = prevState.BurnAsset(signer, reserveFee);

		// Execute Action
		// If gasLimit is less then used gas in action, it throw OutOfGasException
		ActionContext context = CreateContext(state, seed, gasLimit);
		nextState = action.Execute(nextState);

		// Refund unused gas
		UInt256 unusedGas = gasLimit - nextState.GasUsed();
		nextState = nextState.MintAsset(signer, gasPrice * unusedGas);
		
		// Calculate gas fee for collect
		FungibleAssetValue commissionFee = commissionGasPrice * nextState.GasUsed();
		FungibleAssetValue totalFee = gasPrice * nextState.GasUsed();
		
		// Collect gas fee
		// It distribute on next `BeginBlock` timing
		nextState = nextState.MintAsset(feeCollectPool, commissionFee)
		
		// Burn or transfer to community pool
		// If burn, do nothing
		// If transfer to community pool, mint to community pool
		nextState = nextState.MintAsset(communityPool, totalFee - commissionFee)
		
		yield return new ActionEvaluation(nextState);
		
		// calculate next action gas limit
		gasLimit = gasLimit - nextState.GasUsed();
		
		// initialize useGas state to 0
		prevState = nextState.UseGas(0);
	}
}

UInt256 EstimateGas(ITransaction tx, IAccountStateDelta prevState, UInt256 gasLimit, FungibleAssetValue baseGasPrice)
{
	evaluations = ExecuteTx(tx, prevState, remainingGasPerBlock);
	foreach(ActionEvaluation eval in evaluations)
	{
		yield return eval;
		prevState = eval.OutputState;
	}
	return evaluations.Select(x => x.OutputStates.GasUsed).Sum();
}