<?php
/**
 * An abstract visitor class that includes a mapping between functions and classes,
 * simulating overloading.
 *
 * @license http://www.opensource.org/licenses/mit-license.php The MIT License
 * @copyright Copyright 2010-2014 PhpCss Team
 */

namespace PhpCss\Ast\Visitor {

  use PhpCss\Ast;

  /**
   * An abstract visitor class that includes a mapping between functions and classes,
   * simulating overloading.
   */
  abstract class Overload implements Ast\Visitor {

    /**
     * Map the class name of the PhpCss\Ast\Node instance to a method name, validate if it exists and return
     * it as callback.
     *
     * @param Ast\Node $object
     * @param string $prefix
     * @return callable|null
     */
    protected function getMethodByClass(Ast\Node $object, string $prefix = 'visit'): ?callable {
      $method = $prefix.substr(str_replace('\\', '', get_class($object)), 9);
      if (method_exists($this, $method)) {
        return [$this, $method];
      }
      return NULL;
    }

    /**
     * Entering an node in the ast, called before visiting children
     *
     * @param Ast\Node $astNode
     * @return boolean
     */
    public function visitEnter(Ast\Node $astNode): bool {
      if ($method = $this->getMethodByClass($astNode, 'visitEnter')) {
        return $method($astNode);
      }
      return TRUE;
    }

    /**
     * Visiting the $node element
     *
     * @param Ast\Node $astNode
     */
    public function visit(Ast\Node $astNode): void {
      if ($method = $this->getMethodByClass($astNode)) {
        $method($astNode);
      }
    }

    /**
     * Entering an element in the ast, called after visiting children
     *
     * @param Ast\Node $astNode
     * @return void
     */
    public function visitLeave(Ast\Node $astNode): void {
      if ($method = $this->getMethodByClass($astNode, 'visitLeave')) {
        $method($astNode);
      }
    }
  }
}