protected override StepResult ExecuteInternal(TContext ctx)
{
BranchedStagingCache cache = ctx.BeginStagingBranched();
StagingCache longest = null;
bool addRecursion = false;
foreach (ProducerStep <TContext> choice in GetValidChoices(ctx))
{
StagingCache branch = cache.BeginSingleBranch();
StepResult result = choice.Execute(ctx);
if (result == StepResult.AddRecursion)
{
addRecursion = true;
}
else if (result == StepResult.Positive)
{
if (longest == null)
{
goto keepBranch;
}
if (longest.Consumed < branch.Consumed)
{
cache.EndBranch(longest);
goto keepBranch;
}
}
cache.EndBranch(branch);
goto @continue;
keepBranch:
longest = branch;
@continue:
if (longest != null)
{
cache.CurrentBranch = longest;
}
}
if (longest == null)
{
ctx.EndStaging(cache, false);
return(addRecursion ? StepResult.AddRecursion : StepResult.Negative);
}
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);
}