public function testVisitExpressionTreeOfOneLeaf()
{
$expression = ExpressionSymbol::createAdapterForTerminal('a');
$eliminator = new OptionalsEliminator(new IncrementalNamingStrategy());
$eliminator->visitExpression($expression);
$actual = $eliminator->getRoot();
$this->assertEquals($expression, $actual);
}
/**
* @param Expression $e
* @param \Helstern\Nomsky\Grammar\Transformations\EliminateOptionals\OptionalsEliminator $visitor
*
* @return Expression|null
*/
public function walkAndVisitExpression(Expression $e, OptionalsEliminator $visitor)
{
$hierarchicVisitDispatcher = new CompleteVisitDispatcher($visitor);
$walker = new DepthFirstStackBasedWalker();
$walker->walk($e, $hierarchicVisitDispatcher);
$walkResult = $visitor->getRoot();
return $walkResult;
}
/**
* @param Expression $e
* @param NonTerminalNamingStrategy $namingStrategy
*
*@return Expression|null
*/
public function getDepthFirstWalkResult(Expression $e, NonTerminalNamingStrategy $namingStrategy)
{
$visitor = new OptionalsEliminator($namingStrategy);
$hierarchicVisitDispatcher = new CompleteVisitDispatcher($visitor);
$walker = new DepthFirstStackBasedWalker();
$walker->walk($e, $hierarchicVisitDispatcher);
$walkResult = $visitor->getRoot();
return $walkResult;
}
/**
* @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;
}