protected override BoundStatement RewriteDoWhileStatement(BoundDoWhileStatement node)
{
// do
// <body>
// while <condition>
//
// ----->
//
// body:
// <body>
// continue:
// gotoTrue <condition> body
// break:
var bodyLabel = GenerateLabel();
var result = BoundNodeFactory.Block(node.Syntax,
BoundNodeFactory.Label(node.Syntax, bodyLabel),
node.Body,
BoundNodeFactory.Label(node.Syntax, node.ContinueLabel),
BoundNodeFactory.GotoTrue(node.Syntax, bodyLabel, node.Condition),
BoundNodeFactory.Label(node.Syntax, node.BreakLabel)
);
return(RewriteStatement(result));
}
protected override BoundStatement RewriteIfStatement(BoundIfStatement node)
{
if (node.ElseStatement == null)
{
// if <condition>
// <then>
//
// ---->
//
// gotoFalse <condition> end
// <then>
// end:
var endLabel = GenerateLabel();
var result = BoundNodeFactory.Block(node.Syntax,
BoundNodeFactory.GotoFalse(node.Syntax, endLabel, node.Condition),
node.ThenStatement,
BoundNodeFactory.Label(node.Syntax, endLabel)
);
return(RewriteStatement(result));
}
else
{
// if <condition>
// <then>
// else
// <else>
//
// ---->
//
// gotoFalse <condition> else
// <then>
// goto end
// else:
// <else>
// end:
var elseLabel = GenerateLabel();
var endLabel = GenerateLabel();
var result = BoundNodeFactory.Block(node.Syntax,
BoundNodeFactory.GotoFalse(node.Syntax, elseLabel, node.Condition),
node.ThenStatement,
BoundNodeFactory.Goto(node.Syntax, endLabel),
BoundNodeFactory.Label(node.Syntax, elseLabel),
node.ElseStatement,
BoundNodeFactory.Label(node.Syntax, endLabel)
);
return(RewriteStatement(result));
}
}
protected override BoundStatement RewriteForStatement(BoundForStatement node)
{
// for <var> = <lower> to <upper>
// <body>
//
// ---->
//
// {
// var <var> = <lower>
// let upperBound = <upper>
// while (<var> <= upperBound)
// {
// <body>
// continue:
// <var> = <var> + 1
// }
// }
var lowerBound = BoundNodeFactory.VariableDeclaration(node.Syntax, node.Variable, node.LowerBound);
var upperBound = BoundNodeFactory.ConstantDeclaration(node.Syntax, "upperBound", node.UpperBound);
var result = BoundNodeFactory.Block(node.Syntax,
lowerBound,
upperBound,
BoundNodeFactory.While(node.Syntax,
BoundNodeFactory.LessOrEqual(
node.Syntax,
BoundNodeFactory.Variable(node.Syntax, lowerBound),
BoundNodeFactory.Variable(node.Syntax, upperBound)
),
BoundNodeFactory.Block(
node.Syntax,
node.Body,
BoundNodeFactory.Label(node.Syntax, node.ContinueLabel),
BoundNodeFactory.Increment(
node.Syntax,
BoundNodeFactory.Variable(node.Syntax, lowerBound)
)
),
node.BreakLabel,
continueLabel: GenerateLabel()));
return(RewriteStatement(result));
}