private void CFGReductionPhase1(CFG cfg)
{
//phase 1
HashSet <CFGVariable> allNeededTransitions = new HashSet <CFGVariable>();
//create first list containing terminal symbols
foreach (KeyValuePair <string, CFGVariable> valuePair in cfg.AllTransitions)
{
if (valuePair.Value.ContainsTerminals())
{
allNeededTransitions.Add(valuePair.Value);
}
}
//create hashset of variables that can reach a terminal
int transitionLength = 0;
while (transitionLength != allNeededTransitions.Count())
{
transitionLength = allNeededTransitions.Count();
foreach (KeyValuePair <string, CFGVariable> valuePair in cfg.AllTransitions)
{
foreach (List <ILetterOrVariable> transition in valuePair.Value.ToVariablesOrLetters)
{
int counter = 0;
foreach (ILetterOrVariable letOrVar in transition)
{
if (allNeededTransitions.Contains(letOrVar))
{
counter++;
}
}
if (counter == transition.Count)
{
allNeededTransitions.Add(valuePair.Value);
}
}
}
}
cfg.PruneNotIncludedVariables(allNeededTransitions);
}