/**
* @param array $nonTerminals
*
* @return LLParseTableBuilder
*/
public function addNonTerminals(array $nonTerminals)
{
$set = new ArraySet();
foreach ($nonTerminals as $symbol) {
$set->add($symbol);
}
$this->nonTerminals = $set;
return $this;
}
/**
* @param Symbol $nonTerminal
* @param SymbolPredicate $acceptPredicate
* @return ArraySet
*/
public function filterTerminalSet(Symbol $nonTerminal, SymbolPredicate $acceptPredicate)
{
$terminalSetIterator = $this->getTerminalSetIterator($nonTerminal);
$filtered = new ArraySet();
while ($terminalSetIterator->valid()) {
$terminal = $terminalSetIterator->current();
$terminalSetIterator->next();
if ($acceptPredicate->matchSymbol($terminal)) {
$filtered->add($terminal);
}
}
return $filtered;
}
/**
* @return LookAheadSets
*/
public static function predictSets()
{
$productions = self::normalizedProductions();
$sets = new LookAheadSets(new SimpleHashKeyFactory());
$set = new ArraySet();
$set->add(StandardSymbol::terminal('a'));
$sets->add($productions[0], $set);
$set = new ArraySet();
$set->add(StandardSymbol::terminal('b'));
$set->add(StandardSymbol::terminal('c'));
$set->add(StandardSymbol::terminal('d'));
$sets->add($productions[1], $set);
$set = new ArraySet();
$set->add(StandardSymbol::terminal('b'));
$sets->add($productions[2], $set);
$set = new ArraySet();
$set->add(StandardSymbol::terminal('c'));
$set->add(StandardSymbol::terminal('d'));
$sets->add($productions[3], $set);
$set = new ArraySet();
$set->add(StandardSymbol::terminal('c'));
$sets->add($productions[4], $set);
$set = new ArraySet();
$set->add(StandardSymbol::terminal('d'));
$sets->add($productions[5], $set);
return $sets;
}
public function testComputeFromListOfNonTerminalsWhichDeriveEpsilon()
{
$nonTerminals = ['A_1' => StandardSymbol::nonTerminal('A_1'), 'A_2' => StandardSymbol::nonTerminal('A_2'), 'A_3' => StandardSymbol::nonTerminal('A_3'), 'A_4' => StandardSymbol::nonTerminal('A_4')];
$terminals = ['b_1' => StandardSymbol::terminal('b_1'), 'b_2' => StandardSymbol::terminal('b_2'), 'b_4' => StandardSymbol::terminal('b_4')];
$parseSets = ['A_1' => [EpsilonSymbol::singletonInstance(), $terminals['b_1']], 'A_2' => [EpsilonSymbol::singletonInstance(), $terminals['b_2']], 'A_3' => [EpsilonSymbol::singletonInstance()], 'A_4' => [EpsilonSymbol::singletonInstance(), $terminals['b_4']]];
$sentence = 'A_2 A_2 A_1 A_3 A_4';
$expectedSet = new ArraySet();
$expectedSet->add($terminals['b_1']);
$expectedSet->add($terminals['b_2']);
$expectedSet->add($terminals['b_4']);
$epsilon = EpsilonSymbol::singletonInstance();
$expectedSet->add($epsilon);
$actualSet = $this->buildFirstSet($sentence, $parseSets, $nonTerminals, $terminals);
$this->assertEquals($expectedSet->count(), $actualSet->count(), 'unexpected number of actual items found');
/** @var Symbol $symbol */
foreach ($actualSet as $symbol) {
$contains = $expectedSet->contains($symbol);
$this->assertTrue($contains, sprintf('Symbol %s not found', $symbol->toString()));
}
}