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<?php |
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declare(strict_types=1); |
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namespace Antlr\Antlr4\Runtime\Atn\SemanticContexts; |
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use Antlr\Antlr4\Runtime\Comparison\Equality; |
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use Antlr\Antlr4\Runtime\Comparison\Hasher; |
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use Antlr\Antlr4\Runtime\Recognizer; |
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use Antlr\Antlr4\Runtime\RuleContext; |
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use Antlr\Antlr4\Runtime\Utils\Set; |
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/** |
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* A semantic context which is true whenever none of the contained contexts |
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* is false. |
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*/ |
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final class AndOperator extends Operator |
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{ |
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/** @var array<SemanticContext> */ |
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public $operands; |
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public function __construct(SemanticContext $a, SemanticContext $b) |
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{ |
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/** @var Set<SemanticContext> $operands */ |
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$operands = new Set(); |
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if ($a instanceof self) { |
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$operands->addAll($a->operands); |
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} else { |
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$operands->add($a); |
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} |
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if ($b instanceof self) { |
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$operands->addAll($b->operands); |
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} else { |
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$operands->add($b); |
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} |
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/** @var array<PrecedencePredicate> $precedencePredicates */ |
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$precedencePredicates = self::filterPrecedencePredicates($operands); |
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if (\count($precedencePredicates) !== 0) { |
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// interested in the transition with the lowest precedence |
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/** @var PrecedencePredicate $reduced */ |
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$reduced = self::minPredicate($precedencePredicates); |
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$operands->add($reduced); |
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} |
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$this->operands = $operands->getValues(); |
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} |
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/** |
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* @return array<SemanticContext> |
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*/ |
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public function getOperands() : array |
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{ |
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return $this->operands; |
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} |
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/** |
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* {@inheritdoc} |
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* |
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* The evaluation of predicates by this context is short-circuiting, but |
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* unordered. |
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*/ |
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public function eval(Recognizer $parser, RuleContext $parserCallStack) : bool |
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{ |
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foreach ($this->operands as $operand) { |
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if (!$operand->eval($parser, $parserCallStack)) { |
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return false; |
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} |
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} |
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return true; |
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} |
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public function evalPrecedence(Recognizer $parser, RuleContext $parserCallStack) : ?SemanticContext |
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{ |
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$differs = false; |
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$operands = []; |
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foreach ($this->operands as $iValue) { |
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$context = $iValue; |
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$evaluated = $context->evalPrecedence($parser, $parserCallStack); |
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$differs |= $evaluated !== $context; |
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// The AND context is false if any element is false |
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if ($evaluated === null) { |
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return null; |
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} |
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if ($evaluated !== SemanticContext::none()) { |
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// Reduce the result by skipping true elements |
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$operands[] = $evaluated; |
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} |
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} |
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if (!$differs) { |
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return $this; |
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} |
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// all elements were true, so the AND context is true |
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if (\count($operands) === 0) { |
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return SemanticContext::none(); |
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} |
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$result = null; |
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foreach ($operands as $operand) { |
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$result = $result === null ? $operand : self::andContext($result, $operand); |
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} |
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return $result; |
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} |
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public function equals(object $other) : bool |
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{ |
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if ($this === $other) { |
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return true; |
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} |
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if (!$other instanceof self) { |
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return false; |
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} |
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return Equality::equals($this->operands, $other->operands); |
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} |
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public function hashCode() : int |
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{ |
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return Hasher::hash(41, $this->operands); |
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} |
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public function __toString() : string |
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{ |
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$s = ''; |
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foreach ($this->operands as $o) { |
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$s .= '&& ' . $o; |
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} |
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return \strlen($s) > 3 ? (string) \substr($s, 3) : $s; |
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} |
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/** |
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* @param array<PrecedencePredicate> $predicates |
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*/ |
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private static function minPredicate(array $predicates) : object |
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{ |
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$iterator = new \ArrayIterator($predicates); |
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$candidate = $iterator->current(); |
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$iterator->next(); |
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while ($iterator->valid()) { |
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$next = $iterator->current(); |
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$iterator->next(); |
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if ($next->compareTo($candidate) < 0) { |
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$candidate = $next; |
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} |
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} |
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return $candidate; |
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} |
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} |
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In PHP, under loose comparison (like
==
, or!=
, orswitch
conditions), values of different types might be equal.For
integer
values, zero is a special case, in particular the following results might be unexpected: