public override void VisitTryStatement(TryStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.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 VisitDoStatement(DoStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.Fix(node));
}
else
{
MaybeCreateNewState();
var nextState = GetNextState(node);
var conditionState = new State(this)
{
BreakState = nextState
};
var iterationState = currentState;
conditionState.Add(Cs.If(YieldThisFixer.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;
}
}
public static T Fix <T>(T method) where T : CSharpSyntaxNode
{
// This idea isn't going to work because it leaves the syntax tree in a bad state.
// We need to fix the this references after we've done all the semanatic analysis.
// Not sure the best timing for that yet.
var fixer = new YieldThisFixer();
method = (T)method.Accept(fixer);
return(method);
}
public override void VisitLocalDeclarationStatement(LocalDeclarationStatementSyntax node)
{
var semanticModel = compilation.GetSemanticModel(node.SyntaxTree);
// Convert the variable declaration to an assignment expression statement
foreach (var variable in node.Declaration.Variables)
{
if (variable.Initializer != null)
{
var assignment = SyntaxFactory.IdentifierName(variable.Identifier.ToString()).Assign(variable.Initializer.Value);
currentState.Add(Cs.Express(YieldThisFixer.Fix(assignment)));
}
// Hoist the variable into a field
var symbol = (ILocalSymbol)ModelExtensions.GetDeclaredSymbol(semanticModel, variable);
node = (LocalDeclarationStatementSyntax)HoistVariable(node, variable.Identifier, symbol.Type.ToTypeSyntax());
}
}
public override void VisitYieldStatement(YieldStatementSyntax node)
{
var nextState = GetNextState(node);
if (node.ReturnOrBreakKeyword.IsKind(SyntaxKind.BreakKeyword))
{
currentState.Add(ChangeState(nextState));
currentState.Add(Cs.Return(Cs.False()));
}
else
{
currentState.Add(ChangeState(nextState));
currentState.Add(Cs.Express(Cs.This().Member("Current").Assign(YieldThisFixer.Fix(node.Expression))));
currentState.Add(Cs.Return(Cs.True()));
}
SetClosed(currentState);
currentState = nextState;
}
public override void VisitWhileStatement(WhileStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.Fix(node));
}
else
{
MaybeCreateNewState();
var nextState = GetNextState(node);
var iterationState = currentState;
iterationState.NextState = nextState;
iterationState.BreakState = nextState;
node = node.WithStatement(SyntaxFactory.Block(CaptureState(node.Statement, iterationState, nextState)));
iterationState.Statements.Add(node);
Close(iterationState);
currentState = nextState;
}
}
public override void VisitGotoStatement(GotoStatementSyntax node)
{
currentState.Add(YieldThisFixer.Fix(node));
currentState.Add(GotoTop());
SetClosed(currentState);
}
public override void VisitThrowStatement(ThrowStatementSyntax node)
{
currentState.Add(YieldThisFixer.Fix(node));
}
public override void VisitExpressionStatement(ExpressionStatementSyntax node)
{
currentState.Add(YieldThisFixer.Fix(node));
}
public override void VisitForEachStatement(ForEachStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.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, YieldThisFixer.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(YieldThisFixer.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(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(YieldThisFixer.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(YieldThisFixer.Fix(incrementor)));
}
Close(postState);
}
else
{
postState = iterationState;
}
iterationState.NextState = nextState;
iterationState.BreakState = nextState;
var forStatement = SyntaxFactory.WhileStatement(node.Condition ?? Cs.True(), SyntaxFactory.Block(CaptureState(node.Statement, postState, nextState)));
iterationState.Statements.Add(forStatement);
Close(iterationState);
currentState = nextState;
}
}