private void StepForward(ICollection <InterpretTrace> result, ICollection <int> states, InterpretTrace context, int symbol, int symbolPosition, PreventContextType preventContextType)
{
foreach (var transition in context.EndContext.State.OutgoingTransitions)
{
if (transition.IsContext)
{
PopContextTransition popContextTransition = transition as PopContextTransition;
if (popContextTransition != null && context.EndContext.Parent != null)
{
if (popContextTransition.ContextIdentifiers[0] != context.EndContext.Parent.Context)
{
continue;
}
}
switch (preventContextType)
{
case PreventContextType.Pop:
if (!transition.IsRecursive && (transition is PopContextTransition))
{
continue;
}
break;
case PreventContextType.PopRecursive:
if (transition.IsRecursive && (transition is PopContextTransition))
{
continue;
}
break;
case PreventContextType.Push:
if (!transition.IsRecursive && (transition is PushContextTransition))
{
continue;
}
break;
case PreventContextType.PushRecursive:
if (transition.IsRecursive && (transition is PushContextTransition))
{
continue;
}
break;
default:
break;
}
}
InterpretTrace step;
if (context.TryStepForward(transition, symbol, symbolPosition, out step))
{
if (transition.IsMatch)
{
result.Add(step);
continue;
}
bool recursive = transition.TargetState.IsForwardRecursive;
bool addRecursive = false;
if (recursive)
{
addRecursive = !states.Contains(transition.TargetState.Id);
if (!addRecursive && (!(transition is PopContextTransition) || context.EndContext.Parent == null))
{
continue;
}
}
if (addRecursive)
{
states.Add(transition.TargetState.Id);
}
PreventContextType nextPreventContextType = PreventContextType.None;
if (context.EndContext.State.IsOptimized)
{
if (transition is PushContextTransition)
{
nextPreventContextType = transition.IsRecursive ? PreventContextType.PushRecursive : PreventContextType.Push;
}
else if (transition is PopContextTransition)
{
nextPreventContextType = transition.IsRecursive ? PreventContextType.PopRecursive : PreventContextType.Pop;
}
}
StepForward(result, states, step, symbol, symbolPosition, nextPreventContextType);
if (addRecursive)
{
states.Remove(transition.TargetState.Id);
}
}
}
}
private void StepBackward(ICollection <InterpretTrace> result, ICollection <int> states, InterpretTrace context, int symbol, int symbolPosition, PreventContextType preventContextType)
{
foreach (var transition in context.StartContext.State.IncomingTransitions)
{
if (transition.SourceState.IsOptimized)
{
switch (preventContextType)
{
case PreventContextType.Pop:
if (!transition.IsRecursive && (transition is PopContextTransition))
{
continue;
}
break;
case PreventContextType.PopRecursive:
if (transition.IsRecursive && (transition is PopContextTransition))
{
continue;
}
break;
case PreventContextType.Push:
if (!transition.IsRecursive && (transition is PushContextTransition))
{
continue;
}
break;
case PreventContextType.PushRecursive:
if (transition.IsRecursive && (transition is PushContextTransition))
{
continue;
}
break;
default:
break;
}
}
InterpretTrace step;
if (context.TryStepBackward(transition, symbol, symbolPosition, out step))
{
if (transition.IsMatch)
{
result.Add(step);
continue;
}
bool recursive = transition.SourceState.IsBackwardRecursive;
if (recursive && states.Contains(transition.SourceState.Id))
{
// TODO: check postfix rule
continue;
}
if (recursive)
{
states.Add(transition.SourceState.Id);
}
PreventContextType nextPreventContextType = PreventContextType.None;
if (context.StartContext.State.IsOptimized)
{
if (transition is PushContextTransition)
{
nextPreventContextType = transition.IsRecursive ? PreventContextType.PushRecursive : PreventContextType.Push;
}
else if (transition is PopContextTransition)
{
nextPreventContextType = transition.IsRecursive ? PreventContextType.PopRecursive : PreventContextType.Pop;
}
}
StepBackward(result, states, step, symbol, symbolPosition, nextPreventContextType);
if (recursive)
{
states.Remove(transition.SourceState.Id);
}
}
}
}
