public void ShouldTranslateALoopWithABreakStatement()
{
var intVariable = Expression.Variable(typeof(int), "i");
var intGreaterThanTwo = Expression.GreaterThan(intVariable, Expression.Constant(2));
var breakLoop = Expression.Break(Expression.Label());
var ifGreaterThanTwoBreak = Expression.IfThen(intGreaterThanTwo, breakLoop);
var writeLine = CreateLambda(() => Console.WriteLine());
var incrementVariable = Expression.Increment(intVariable);
var loopBody = Expression.Block(ifGreaterThanTwoBreak, writeLine.Body, incrementVariable);
var loop = Expression.Loop(loopBody, breakLoop.Target);
var translated = ToReadableString(loop);
const string EXPECTED = @"
while (true)
{
if (i > 2)
{
break;
}
Console.WriteLine();
++i;
}";
translated.ShouldBe(EXPECTED.TrimStart());
}
private static Expression GetReturnStatementBlock(out ParameterExpression existingInts)
{
existingInts = Expression.Variable(typeof(List <int>), "ints");
var existingIntsEnumerator = Expression.Variable(typeof(List <int> .Enumerator), "enumerator");
var getEnumeratorMethod = existingInts.Type.GetPublicInstanceMethod("GetEnumerator");
var getEnumeratorCall = Expression.Call(existingInts, getEnumeratorMethod);
var enumeratorAssignment = Expression.Assign(existingIntsEnumerator, getEnumeratorCall);
var enumeratorMoveNextMethod = existingIntsEnumerator.Type.GetPublicInstanceMethod("MoveNext");
var enumeratorMoveNextCall = Expression.Call(existingIntsEnumerator, enumeratorMoveNextMethod);
var enumeratorItem = Expression.Variable(typeof(int), "item");
var enumeratorCurrent = Expression.Property(existingIntsEnumerator, "Current");
var itemAssignment = Expression.Assign(enumeratorItem, enumeratorCurrent);
var intsAddMethod = existingInts.Type.GetPublicInstanceMethod("Add");
var intsAddCall = Expression.Call(existingInts, intsAddMethod, enumeratorItem);
var addItemBlock = Expression.Block(
new[] { enumeratorItem },
itemAssignment,
intsAddCall);
var loopBreakTarget = Expression.Label(typeof(void), "LoopBreak");
var conditionallyAddItems = Expression.Condition(
Expression.IsTrue(enumeratorMoveNextCall),
addItemBlock,
Expression.Break(loopBreakTarget));
var addItemsLoop = Expression.Loop(conditionallyAddItems, loopBreakTarget);
var populateExistingInts = Expression.Block(
new[] { existingIntsEnumerator },
enumeratorAssignment,
addItemsLoop);
var conditionFalseBlock = Expression.Block(
populateExistingInts,
existingInts);
var valueConditional = Expression.Condition(
Expression.Equal(existingInts, Expression.Default(existingInts.Type)),
Expression.New(conditionFalseBlock.Type),
conditionFalseBlock);
return(valueConditional);
}
