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<?php
/*
* This file is part of the Symfony package.
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Symfony\Component\ExpressionLanguage;
use Psr\Cache\CacheItemPoolInterface;
use Symfony\Component\Cache\Adapter\ArrayAdapter;
/**
* Allows to compile and evaluate expressions written in your own DSL.
*
* @author Fabien Potencier <fabien@symfony.com>
*/
class ExpressionLanguage
{
private $cache;
private $lexer;
private $parser;
private $compiler;
protected $functions = [];
/**
* @param ExpressionFunctionProviderInterface[] $providers
*/
public function __construct(CacheItemPoolInterface $cache = null, array $providers = [])
{
$this->cache = $cache ?? new ArrayAdapter();
$this->registerFunctions();
foreach ($providers as $provider) {
$this->registerProvider($provider);
}
}
/**
* Compiles an expression source code.
*
* @param Expression|string $expression The expression to compile
* @param array $names An array of valid names
*
* @return string The compiled PHP source code
*/
public function compile($expression, $names = [])
{
return $this->getCompiler()->compile($this->parse($expression, $names)->getNodes())->getSource();
}
/**
* Evaluate an expression.
*
* @param Expression|string $expression The expression to compile
* @param array $values An array of values
*
* @return mixed The result of the evaluation of the expression
*/
public function evaluate($expression, $values = [])
{
return $this->parse($expression, array_keys($values))->getNodes()->evaluate($this->functions, $values);
}
/**
* Parses an expression.
*
* @param Expression|string $expression The expression to parse
* @param array $names An array of valid names
*
* @return ParsedExpression A ParsedExpression instance
*/
public function parse($expression, $names)
{
if ($expression instanceof ParsedExpression) {
return $expression;
}
asort($names);
$cacheKeyItems = [];
foreach ($names as $nameKey => $name) {
$cacheKeyItems[] = \is_int($nameKey) ? $name : $nameKey.':'.$name;
}
$cacheItem = $this->cache->getItem(rawurlencode($expression.'//'.implode('|', $cacheKeyItems)));
if (null === $parsedExpression = $cacheItem->get()) {
$nodes = $this->getParser()->parse($this->getLexer()->tokenize((string) $expression), $names);
$parsedExpression = new ParsedExpression((string) $expression, $nodes);
$cacheItem->set($parsedExpression);
$this->cache->save($cacheItem);
}
return $parsedExpression;
}
/**
* Registers a function.
*
* @param string $name The function name
* @param callable $compiler A callable able to compile the function
* @param callable $evaluator A callable able to evaluate the function
*
* @throws \LogicException when registering a function after calling evaluate(), compile() or parse()
*
* @see ExpressionFunction
*/
public function register($name, callable $compiler, callable $evaluator)
{
if (null !== $this->parser) {
throw new \LogicException('Registering functions after calling evaluate(), compile() or parse() is not supported.');
}
$this->functions[$name] = ['compiler' => $compiler, 'evaluator' => $evaluator];
}
public function addFunction(ExpressionFunction $function)
{
$this->register($function->getName(), $function->getCompiler(), $function->getEvaluator());
}
public function registerProvider(ExpressionFunctionProviderInterface $provider)
{
foreach ($provider->getFunctions() as $function) {
$this->addFunction($function);
}
}
protected function registerFunctions()
{
$this->addFunction(ExpressionFunction::fromPhp('constant'));
}
private function getLexer(): Lexer
{
if (null === $this->lexer) {
$this->lexer = new Lexer();
}
return $this->lexer;
}
private function getParser(): Parser
{
if (null === $this->parser) {
$this->parser = new Parser($this->functions);
}
return $this->parser;
}
private function getCompiler(): Compiler
{
if (null === $this->compiler) {
$this->compiler = new Compiler($this->functions);
}
return $this->compiler->reset();
}
}