private IEnumerable <Instruction> _ProcessLoopBody(LoopBodyTransformer bodyTransformer, Label continueLabel, Label breakLabel)
{
var oldEnclosing = _enclosingLoop;
_enclosingLoop = new LoopDescriptor(continueLabel, breakLabel);
// ToArray (or any form of materialization) is important to ensure that the body is actually processed at this place.
var result = bodyTransformer().ToArray();
_enclosingLoop = oldEnclosing;
return(result);
}
public override IEnumerable <Instruction> VisitDoStatement(DoStatementSyntax node)
{
LoopBodyTransformer bodyTransformer = () => node.Statement?.Accept(this) ?? Enumerable.Empty <Instruction>();
var loopEntry = new Label();
var loopExit = new Label();
var continueLabel = new Label();
var transformed = new List <Instruction>();
transformed.Add(loopEntry);
transformed.AddRange(_ProcessLoopBody(bodyTransformer, continueLabel, loopExit));
transformed.Add(continueLabel);
transformed.Add(new ConditionalJump(_expressionFactory.Create(node.Condition), loopEntry));
transformed.Add(loopExit);
return(transformed);
}
private IEnumerable <Instruction> _CreateLoop(ExpressionSyntax condition, LoopBodyTransformer bodyTransformer, Label continueLabel)
{
var loopEntry = new Label();
var loopExit = new Label();
var loopBody = new Label();
continueLabel = continueLabel ?? loopEntry;
var transformed = new List <Instruction>();
transformed.Add(loopEntry);
transformed.Add(condition == null ? (Instruction) new Jump(loopBody) : new ConditionalJump(_expressionFactory.Create(condition), loopBody));
transformed.Add(new Jump(loopExit));
transformed.Add(loopBody);
transformed.AddRange(_ProcessLoopBody(bodyTransformer, continueLabel, loopExit));
transformed.Add(new Jump(loopEntry));
transformed.Add(loopExit);
return(transformed);
}
public override IEnumerable <Instruction> VisitForStatement(ForStatementSyntax node)
{
var transformed = new List <Instruction>();
if (node.Declaration != null)
{
transformed.AddRange(node.Declaration.Accept(this));
}
transformed.AddRange(node.Initializers.SelectMany(initializer => initializer.Accept(this)));
var continueLabel = new Label();
LoopBodyTransformer bodyTransformer = () => {
var body = new List <Instruction>();
body.AddRange(node.Statement.Accept(this));
body.Add(continueLabel);
body.AddRange(node.Incrementors.SelectMany(incrementor => incrementor.Accept(this)));
return(body);
};
transformed.AddRange(_CreateLoop(node.Condition, bodyTransformer, continueLabel));
return(transformed);
}
public override IEnumerable <Instruction> VisitWhileStatement(WhileStatementSyntax node)
{
LoopBodyTransformer bodyTransformer = () => node.Statement?.Accept(this) ?? Enumerable.Empty <Instruction>();
return(_CreateLoop(node.Condition, bodyTransformer, null));
}
