/**
* @param Production $production
* @return array|Production[]
*/
public function transform(Production $production)
{
$expression = $production->getExpression();
$visitor = new Visitor();
$hierarchicVisitDispatcher = new CompleteVisitDispatcher($visitor);
$walker = new DepthFirstStackBasedWalker();
$walker->walk($expression, $hierarchicVisitDispatcher);
$rootExpression = $visitor->getRoot();
$production = new StandardProduction($production->getNonTerminal(), $rootExpression);
return array($production);
}
/**
* @param Production $production
* @return array|Production[]
*/
public function transform(Production $production)
{
$expression = $production->getExpression();
if ($expression instanceof Choice) {
$productions = array();
$expressions = iterator_to_array($expression->getIterator());
foreach ($expressions as $expression) {
$productions[] = new StandardProduction($production->getNonTerminal(), $expression);
}
return $productions;
}
return array($production);
}
/**
* @param Production $initialProduction
* @return array|Production[]
*/
public function transform(Production $initialProduction)
{
$expression = $initialProduction->getExpression();
$visitor = new OptionalsEliminator($this->nonTerminalNamingStrategy);
$hierarchicVisitDispatcher = new CompleteVisitDispatcher($visitor);
$walker = new DepthFirstStackBasedWalker();
$walker->walk($expression, $hierarchicVisitDispatcher);
$visitRoot = $visitor->getRoot();
$cleanedProduction = new StandardProduction($initialProduction->getNonTerminal(), $visitRoot);
$cleanedProductionsList = array($cleanedProduction);
$cleanedProductionsList = array_merge($cleanedProductionsList, $visitor->getEpsilonAlternatives());
return $cleanedProductionsList;
}
/**
* @param \Helstern\Nomsky\Grammar\Production\Production $p
*
* @return \Helstern\Nomsky\GrammarAnalysis\Production\NormalizedProduction
* @throws \Exception
*/
public function normalizeProduction(Production $p)
{
$expression = $p->getExpression();
if ($expression instanceof ExpressionSymbol) {
$lhs = $p->getNonTerminal();
$normalized = $this->processExpressionSymbolProduction($lhs, $expression);
return $normalized;
}
if ($expression instanceof Concatenation) {
$lhs = $p->getNonTerminal();
$normalized = $this->processConcatenationProduction($lhs, $expression);
return $normalized;
}
throw new \Exception('the production has not been simplified enough');
}
