public override void VisitWhile(BoundWhile node)
{
// Rules for while:
// * When IsFalse(Test), we don't have any work;
// * When IsTrue(Test), _branch stays the default;
// * Otherwise, _branch becomes a fork;
// * Target for break/continue.
var result = ToBoolean(node.Test);
// If Test evaluates to a constant expression false, the while
// loop is never taken.
if (result == false)
return;
// The Test is executed on the default branch.
Visit(node.Test);
var block = new Block(_branch, FindLabel(node), true, true, null);
PushBlock(block);
_branch = block.Branch.Fork();
Visit(node.Body);
block.JoinBranch(_branch);
// Create an empty fork to tell the Join algorithm that the
// Body was an optional branch.
if (result != true)
block.JoinBranch(block.Branch.Fork());
PopBlock(block);
}
public virtual void VisitWhile(BoundWhile node)
{
DefaultVisit(node);
}
private void EmitWhile(BoundWhile node)
{
// Create the break and continue targets and push them onto the stack.
var breakTarget = IL.DefineLabel(GetLabel(node));
_scope.BreakTargets.Push(breakTarget);
var continueTarget = IL.DefineLabel(GetLabel(node));
_scope.ContinueTargets.Push(continueTarget);
// At the beginning of every iteration, perform the test.
IL.MarkLabel(continueTarget);
EmitTest(node.Test, breakTarget.Label, true);
// Emit the body.
EmitStatement(node.Body);
// Go back to the start to perform the test again.
IL.Emit(OpCodes.Br, continueTarget.Label);
// After the loop.
IL.MarkLabel(breakTarget);
// Pop the break and continue targets to make the previous ones
// available.
_scope.BreakTargets.Pop();
_scope.ContinueTargets.Pop();
}
