protected override StepResult ExecuteInternal(TContext ctx)
{
StagingCache cache = ctx.BeginStaging();
StepResult result = child.Execute(ctx);
if (result != StepResult.Positive)
{
ctx.EndStaging(cache, false);
return(result);
}
while (child.Execute(ctx) == StepResult.Positive)
{
;
}
ctx.EndStaging(cache, true, false);
ctx.AddSymbol(new Production(Name, cache.Symbols));
return(StepResult.Positive);
}
protected override StepResult ExecuteInternal(TContext ctx)
{
BranchedStagingCache cache = ctx.BeginStagingBranched();
StagingCache posBranch = cache.BeginSingleBranch();
StepResult posResult = a.Execute(ctx);
if (posResult == StepResult.Positive)
{
StagingCache negBranch = cache.BeginSingleBranch();
StepResult negResult = b.Execute(ctx);
switch (negResult)
{
case StepResult.Negative:
cache.EndBranch(negBranch, posBranch);
ctx.EndStaging(cache, true, false);
ctx.AddSymbol(new Production(Name, cache.Symbols));
return(StepResult.Positive);
case StepResult.Positive:
if (negBranch.Consumed < posBranch.Consumed)
{
goto case StepResult.Negative;
}
posResult = StepResult.Negative;
break;
case StepResult.AddRecursion:
posResult = StepResult.AddRecursion;
break;
}
}
ctx.EndStaging(cache, false);
return(posResult);
}
