SingleFileSourceLocator is too ineffective about unknown identifiers

[ondrejmirtes]

When asked about an unknown identifier, it always parses the source code again.

Instead, it should parse the file only a single time and remember all the parsed symbols.

I know there's MemoizingSourceLocator but it doesn't help really. It will only remember null when asked about the same identifiers for the second time.

[ondrejmirtes]

My PoC implementation that works well: https://github.com/phpstan/phpstan-src/blob/master/src/Reflection/BetterReflection/SourceLocator/OptimizedSingleFileSourceLocator.php

[Ocramius]

Possibly related to how the AbstractSourceLocator does not cache the created "located source":

BetterReflection/src/SourceLocator/Type/AbstractSourceLocator.php

Lines 39 to 49 in 5b2a0a7

	$locatedSource = $this->createLocatedSource($identifier);
	if (! $locatedSource) {
	return null;
	}
	try {
	return $this->astLocator->findReflection($reflector, $locatedSource, $identifier);
	} catch (IdentifierNotFound) {
	return null;
	}

BetterReflection/src/SourceLocator/Type/AbstractSourceLocator.php

Lines 52 to 59 in 5b2a0a7

	/**
	* {@inheritDoc}
	*
	* @throws ParseToAstFailure
	*/
	final public function locateIdentifiersByType(Reflector $reflector, IdentifierType $identifierType): array
	{
	$locatedSource = $this->createLocatedSource(new Identifier(Identifier::WILDCARD, $identifierType));

Note how the entire source is re-created each time:

BetterReflection/src/SourceLocator/Type/SingleFileSourceLocator.php

Lines 36 to 49 in 5b2a0a7

	/**
	* {@inheritDoc}
	*
	* @throws InvalidArgumentException
	* @throws InvalidFileLocation
	*/
	protected function createLocatedSource(Identifier $identifier): ?LocatedSource
	{
	return new LocatedSource(
	file_get_contents($this->fileName),
	$identifier->getName(),
	$this->fileName,
	);
	}

We can most likely avoid the expensive I/O operations ( file_get_contents() ), at the price of more memory usage.

Still, the AstLocator will then repeat the traversal of the whole tree of symbols:

BetterReflection/src/SourceLocator/Ast/Locator.php

Lines 58 to 69 in 5b2a0a7

	public function findReflectionsOfType(
	Reflector $reflector,
	LocatedSource $locatedSource,
	IdentifierType $identifierType,
	): array {
	try {
	return $this->findReflectionsInTree->__invoke(
	$reflector,
	$this->parser->parse($locatedSource->getSource()),
	$identifierType,
	$locatedSource,
	);