<?php
namespace JmesPath;

/**
* Uses an external tree visitor to interpret an AST.
*/
class AstRuntime
{
private $parser;
private $interpreter;
private $cache = [];
private $cachedCount = 0;

public function __construct(
?Parser $parser = null,
?callable $fnDispatcher = null
) {
$fnDispatcher = $fnDispatcher ?: FnDispatcher::getInstance();
$this->interpreter = new TreeInterpreter($fnDispatcher);
$this->parser = $parser ?: new Parser();
}

/**
* Returns data from the provided input that matches a given JMESPath
* expression.
*
* @param string $expression JMESPath expression to evaluate
* @param mixed $data Data to search. This data should be data that
* is similar to data returned from json_decode
* using associative arrays rather than objects.
*
* @return mixed Returns the matching data or null
*/
public function __invoke($expression, $data)
{
if (!isset($this->cache[$expression])) {
// Clear the AST cache when it hits 1024 entries
if (++$this->cachedCount > 1024) {
$this->cache = [];
$this->cachedCount = 0;
}
$this->cache[$expression] = $this->parser->parse($expression);
}

return $this->interpreter->visit($this->cache[$expression], $data);
}
}