public override void VisitUsingStatement(UsingStatementSyntax node)
{
var afterTry = GetNextState();
var newTryStatement = Js.Try();
// Keep track of exception, if any, so we can rethrow
var exceptionIdentifier = HoistVariable(new LiftedVariableKey("$usingex"));
// Identifier for caught exception
var caughtExceptionIdentifier = UniqueName("$caughtex");
// Hoist the variable into a field
var disposables = new List <JsExpression>();
if (node.Declaration != null)
{
foreach (var variable in node.Declaration.Variables)
{
var symbol = (ILocalSymbol)Transformer.Model.GetDeclaredSymbol(variable);
var identifier = HoistVariable(new LiftedVariableKey(variable.Identifier, symbol));
var name = identifier.GetReference();
disposables.Add(name);
CurrentState.Add(name.Assign((JsExpression)variable.Initializer.Value.Accept(Transformer)).Express());
}
}
if (node.Expression != null)
{
var identifier = Js.Reference(UniqueName("$using"));
disposables.Add(identifier);
CurrentState.Add(identifier.Assign((JsExpression)node.Expression.Accept(Transformer)).Express());
}
var tryState = NewSubstate();
GotoState(tryState);
var finallyState = GetNextState();
CurrentState = finallyState;
foreach (var disposable in disposables)
{
CurrentState.Add(disposable.Member("Dispose").Invoke().Express());
}
CurrentState.Add(Js.If(exceptionIdentifier.GetReference().NotEqualTo(Js.Null()), Js.Throw(exceptionIdentifier.GetReference())));
GotoState(afterTry);
newTryStatement.Catch = Js.Catch(Js.Variable(caughtExceptionIdentifier));
newTryStatement.Catch.Body = Js.Block(
new[] { exceptionIdentifier.GetReference().Assign(Js.Reference(caughtExceptionIdentifier)).Express() }
.Concat(GotoStateStatements(finallyState))
.ToArray()
);
tryState.Wrap = switchStatement =>
{
newTryStatement.Body = Js.Block(switchStatement);
return(newTryStatement);
};
StartSubstate(tryState);
AcceptStatement(node.Statement);
GotoState(finallyState);
EndSubstate();
CurrentState = afterTry;
}
public override void VisitTryStatement(TryStatementSyntax node)
{
var afterTry = GetNextState();
var newTryStatement = Js.Try();
var tryState = NewSubstate();
GotoState(tryState);
// Keep track of exception, if any, so we can rethrow
var exceptionIdentifier = HoistVariable(new LiftedVariableKey("$ex"));
var exceptionVariable = UniqueName("$caughtex");
State finallyState = node.Finally == null ? null : GetNextState();
// Declare a block to store all the catch statements the try statement's only catch clause. (No
// type-specific catch clauses in Javascript
var catchBlock = Js.Block();
// Make sure that the exception is stored in a variable accessible to the entire state machine.
catchBlock.Express(exceptionIdentifier.GetReference().Assign(Js.Reference(exceptionVariable)));
foreach (var catchClause in node.Catches)
{
// Get the symbol that represents the exception declaration (identifier and type)
var symbol = Transformer.Model.GetDeclaredSymbol(catchClause.Declaration);
var exceptionType = symbol == null ? null : symbol.Type;
if (exceptionType == null && catchClause.Declaration != null && catchClause.Declaration.Type != null)
{
exceptionType = (ITypeSymbol)Transformer.Model.GetSymbolInfo(catchClause.Declaration.Type).Symbol;
}
// True if it is actually declaring the variable (as opposed to a catch clause that specifies
// merely an exception type
var hasDeclaration = catchClause.Declaration.Identifier.Kind() != SyntaxKind.None;
// A variable to store the new unique identifier to store the exception
IJsDeclaration newIdentifier;
// Hoist the variable into a field
if (hasDeclaration)
{
newIdentifier = HoistVariable(new LiftedVariableKey(catchClause.Declaration.Identifier, symbol));
}
else
{
newIdentifier = HoistVariable(new LiftedVariableKey(SyntaxFactory.Identifier("ex")));
}
// Collect all the catch statements into the catchState by making that state current
var catchState = GetNextState();
CurrentState = catchState;
AcceptStatement(catchClause.Block);
// Add onto the catch state some commands to go to the next state.
if (finallyState != null)
{
GotoState(finallyState);
}
else
{
GotoState(afterTry);
}
// Create the statements that will live in the actual catch handler, which directs the logic
// to the actual catch state and also stores the exception in the correct identifier.
var thisCatchStatements = Js.Block();
thisCatchStatements.Express(newIdentifier.SetReference().Assign(exceptionIdentifier.GetReference()));
// Apply filter if present
if (catchClause.Filter != null)
{
var filter = (JsExpression)catchClause.Filter.FilterExpression.Accept(Transformer);
thisCatchStatements.Add(Js.If(filter, Js.Block(GotoStateStatements(catchState))));
}
else
{
thisCatchStatements.AddRange(GotoStateStatements(catchState));
}
// Only do the above if the current exception is of the type expected by the catch handler.
var condition = Idioms.Is(exceptionIdentifier.GetReference(), exceptionType);
catchBlock.Add(Js.If(condition, thisCatchStatements));
}
if (node.Finally != null)
{
// Collect the statements of the finally block into the finally state
CurrentState = finallyState;
AcceptStatement(node.Finally.Block);
// If the exception object is not null, then rethrow it. In other words, if this is a finally
// clause that has responded to an exception, we need to propagate the exception rather than
// continue after the try statement. Otherwise, go to the code after the try block.
CurrentState.Add(Js.If(exceptionIdentifier.GetReference().NotEqualTo(Js.Null()),
Js.Throw(exceptionIdentifier.GetReference()),
Js.Block(GotoStateStatements(afterTry))));
// Finally, at the very end of the catch clause (and we can only get here if the logic didn't break
// out as it would with the logic in the catch handlers) go to the finally state.
catchBlock.AddRange(GotoStateStatements(finallyState).ToArray());
}
catchBlock.Add(Js.Throw(exceptionIdentifier.GetReference()));
newTryStatement.Catch = Js.Catch(Js.Variable(exceptionVariable));
newTryStatement.Catch.Body = catchBlock;
tryState.Wrap = switchStatement =>
{
newTryStatement.Body = Js.Block(switchStatement);
return(newTryStatement);
};
StartSubstate(tryState);
AcceptStatement(node.Block);
if (node.Finally != null)
{
GotoState(finallyState);
}
else
{
GotoState(afterTry);
}
EndSubstate();
CurrentState = afterTry;
}
