public void GenerateStates()
{
var lastState = new State(this);
lastState.Statements.Add(ReturnOutOfState());
currentState = new State(this) { NextState = lastState };
node.Accept(this);
// Post-process goto statements
if (labelStates.Any())
{
var gotoSubstituter = new GotoSubstituter(compilation, labelStates);
foreach (var state in states)
{
state.Statements = state.Statements.Select(x => (StatementSyntax)x.Accept(gotoSubstituter)).ToList();
}
}
var lastStatement = states.Last().Statements.LastOrDefault();
if (lastStatement == null || (!(lastStatement is BreakStatementSyntax) && !(lastStatement is ReturnStatementSyntax)))
states.Last().Statements.Add(Cs.Break());
}
protected void MaybeCreateNewState()
{
if (currentState.Statements.Any())
{
var thisState = new State(this);
var oldNextState = currentState.NextState;
thisState.NextState = oldNextState;
currentState.NextState = thisState;
Close(currentState);
currentState = thisState;
}
}
protected StatementSyntax[] CaptureState(CSharpSyntaxNode node, State nextState, State breakState)
{
var catchBatch = new State(this, true) { NextState = nextState };
var oldState = currentState;
currentState = catchBatch;
node.Accept(this);
// If after walking the node, it might leave the current state in an unclosed state. We want to make sure it's closed.
if (currentState != breakState && currentState != catchBatch && currentState != nextState && currentState != oldState)
{
Close(currentState);
}
return catchBatch.Statements.ToArray();
}
public void CloseTo(State fromState, State toState)
{
if (fromState.IsClosed)
return;
if (toState == null)
{
// fromState.Add(ChangeState(toState));
fromState.Add(GotoTop());
SetClosed(fromState);
// SetClosed(Go);
return;
}
// throw new ArgumentNullException("toState");
fromState.Add(ChangeState(toState));
fromState.Add(GotoTop());
SetClosed(fromState);
}
public static StatementSyntax ChangeState(State newState)
{
return Cs.Express(Cs.This().Member(state).Assign(Cs.Integer(newState.Index)));
}
protected void SetClosed(State state)
{
state.IsClosed = true;
if (state.Germ != null)
state.Germ(state);
}
public void Close(State state)
{
CloseTo(state, state.NextState);
}
protected State GetNextState(StatementSyntax node)
{
var nextState = currentState.NextState;
var next = node.GetNextStatement();
if (next != null && !(next is EmptyStatementSyntax))
{
nextState = new State(this) { NextState = currentState.NextState, Germ = currentState.Germ };
}
return nextState;
}
public override void VisitTryStatement(TryStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(StateMachineThisFixer.Fix(node));
}
else
{
if (node.Catches.Any())
throw new Exception("Yield statements cannot be contained inside try/catch blocks.");
var nextState = GetNextState(node);
MaybeCreateNewState();
var tryState = currentState;
tryState.NextState = nextState;
var exceptionName = SyntaxFactory.Identifier("_ex" + exceptionNameCounter++);
var finallyState = new State(this) { NextState = nextState, BreakState = nextState };
foreach (var finallyStatement in node.Finally.Block.Statements)
finallyState.Add(finallyStatement);
finallyState.Add(Cs.If(Cs.This().Member(exceptionName).NotEqualTo(Cs.Null()), Cs.Throw(Cs.This().Member(exceptionName))));
Close(finallyState);
node = (TryStatementSyntax)HoistVariable(node, exceptionName, SyntaxFactory.ParseTypeName("System.Exception"));
tryState.NextState = finallyState;
tryState.Germ = yieldState =>
{
var gotoFinally = SyntaxFactory.Block(
Cs.Express(Cs.This().Member(exceptionName).Assign(SyntaxFactory.IdentifierName(exceptionName))),
ChangeState(finallyState),
GotoTop()
);
var statements = yieldState.Statements.ToArray();
yieldState.Statements.Clear();
yieldState.Statements.Add(Cs.Try().WithBlock(Cs.Block(statements)).WithCatches(SyntaxFactory.List(new[] {
SyntaxFactory.CatchClause(SyntaxFactory.CatchDeclaration(SyntaxFactory.ParseTypeName("System.Exception"), exceptionName), null, gotoFinally) })));
};
node.Block.Accept(this);
if (!tryState.IsClosed)
{
CloseTo(tryState, finallyState);
}
currentState = nextState;
}
}
public override void VisitForEachStatement(ForEachStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(StateMachineThisFixer.Fix(node));
}
else
{
// Convert the variable declaration in the for loop
var semanticModel = compilation.GetSemanticModel(node.SyntaxTree);
var symbol = (ILocalSymbol)ModelExtensions.GetDeclaredSymbol(semanticModel, node);
var targetType = ModelExtensions.GetTypeInfo(semanticModel, node.Expression);
// Hoist the variable into a field
node = (ForEachStatementSyntax)HoistVariable(node, node.Identifier, symbol.Type.ToTypeSyntax());
// Hoist the enumerator into a field
var enumerator = SyntaxFactory.Identifier(node.Identifier + "_enumerator");
var genericEnumeratorType = compilation.FindType("System.Collections.Generic.IEnumerable`1");
var elementType = targetType.ConvertedType.GetGenericArgument(genericEnumeratorType, 0);
var enumeratorType = elementType == null ?
SyntaxFactory.ParseTypeName("System.Collections.IEnumerator") :
SyntaxFactory.ParseTypeName("System.Collections.Generic.IEnumerator<" + elementType.ToDisplayString() + ">");
node = (ForEachStatementSyntax)HoistVariable(node, enumerator, enumeratorType);
currentState.Add(Cs.Express(SyntaxFactory.IdentifierName(enumerator).Assign(SyntaxFactory.InvocationExpression(SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, StateMachineThisFixer.Fix(node.Expression), SyntaxFactory.IdentifierName("GetEnumerator"))))));
// Mostly the same as while loop from here (key word, "mostly"; hence the lack of factoring here)
MaybeCreateNewState();
var nextState = GetNextState(node);
var iterationState = currentState;
iterationState.NextState = iterationState;
iterationState.BreakState = nextState;
var bodyBatch = new State(this, true) { NextState = iterationState.NextState };
// Assign current item
bodyBatch.Add(Cs.Express(SyntaxFactory.IdentifierName(node.Identifier).Assign(SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
SyntaxFactory.IdentifierName(enumerator), SyntaxFactory.IdentifierName("Current")))));
currentState = bodyBatch;
node.Statement.Accept(this);
var moveNext = SyntaxFactory.InvocationExpression(SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, SyntaxFactory.IdentifierName(enumerator), SyntaxFactory.IdentifierName("MoveNext")));
var forStatement = SyntaxFactory.WhileStatement(moveNext, SyntaxFactory.Block(bodyBatch.Statements));
iterationState.Statements.Add(forStatement);
CloseTo(iterationState, nextState);
if (currentState != nextState)
{
Close(currentState);
}
currentState = nextState;
}
}
public override void VisitForStatement(ForStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(StateMachineThisFixer.Fix(node));
}
else
{
var semanticModel = compilation.GetSemanticModel(node.SyntaxTree);
// Convert the variable declarations in the for loop
if (node.Declaration != null)
{
foreach (var variable in node.Declaration.Variables.Where(x => x.Initializer != null))
{
var assignment = SyntaxFactory.IdentifierName(variable.Identifier.ToString()).Assign(StateMachineThisFixer.Fix(variable.Initializer.Value));
currentState.Add(Cs.Express(assignment));
var symbol = (ILocalSymbol)ModelExtensions.GetDeclaredSymbol(semanticModel, variable);
// Hoist the variable into a field
node = (ForStatementSyntax)HoistVariable(node, variable.Identifier, SyntaxFactory.ParseTypeName(symbol.Type.GetFullName()));
}
}
foreach (var initializer in node.Initializers)
{
currentState.Add(Cs.Express(StateMachineThisFixer.Fix(initializer)));
}
MaybeCreateNewState();
var nextState = GetNextState(node);
var iterationState = currentState;
// postState determines where the flow goes after each iteration. If there are incrementors, it goes
// to a state that handles the incrementing, then goes back to the iteration state. Otherwise, the
// iteration state just points back to itself like the while loop.
State postState;
if (node.Incrementors.Any())
{
postState = new State(this);
postState.NextState = iterationState;
foreach (var incrementor in node.Incrementors)
{
postState.Add(Cs.Express(StateMachineThisFixer.Fix(incrementor)));
}
Close(postState);
}
else
{
postState = iterationState;
}
iterationState.NextState = nextState;
iterationState.BreakState = nextState;
var forStatement = SyntaxFactory.WhileStatement(StateMachineThisFixer.Fix(node.Condition) ?? Cs.True(), SyntaxFactory.Block(CaptureState(node.Statement, postState, nextState)));
iterationState.Statements.Add(StateMachineThisFixer.Fix(forStatement));
Close(iterationState);
currentState = nextState;
}
}
public override void VisitDoStatement(DoStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(StateMachineThisFixer.Fix(node));
}
else
{
MaybeCreateNewState();
var nextState = GetNextState(node);
var conditionState = new State(this) { BreakState = nextState };
var iterationState = currentState;
conditionState.Add(Cs.If(StateMachineThisFixer.Fix(node.Condition), ChangeState(iterationState), ChangeState(nextState)));
conditionState.Add(GotoTop());
SetClosed(conditionState);
iterationState.NextState = conditionState;
node.Statement.Accept(this);
if (currentState != nextState)
{
Close(currentState);
}
currentState = nextState;
}
}
