class Twig_Node_Expression_Name

Twig_NodeVisitor_Optimizer::optimizeVariables in drupal/core/vendor/twig/twig/lib/Twig/NodeVisitor/Optimizer.php

class Twig_Node_Expression_Name extends Twig_Node_Expression {
  protected $specialVars = array(
    '_self' => '$this',
    '_context' => '$context',
    '_charset' => '$this->env->getCharset()',
  );
  public function __construct($name, $lineno) {
    parent::__construct(array(), array(
      'name' => $name,
      'is_defined_test' => false,
      'ignore_strict_check' => false,
      'always_defined' => false,
    ), $lineno);
  }
  public function compile(Twig_Compiler $compiler) {
    $name = $this
      ->getAttribute('name');
    if ($this
      ->getAttribute('is_defined_test')) {
      if ($this
        ->isSpecial()) {
        $compiler
          ->repr(true);
      }
      else {
        $compiler
          ->raw('array_key_exists(')
          ->repr($name)
          ->raw(', $context)');
      }
    }
    elseif ($this
      ->isSpecial()) {
      $compiler
        ->raw($this->specialVars[$name]);
    }
    elseif ($this
      ->getAttribute('always_defined')) {
      $compiler
        ->raw('$context[')
        ->string($name)
        ->raw(']');
    }
    else {

      // remove the non-PHP 5.4 version when PHP 5.3 support is dropped
      // as the non-optimized version is just a workaround for slow ternary operator
      // when the context has a lot of variables
      if (version_compare(phpversion(), '5.4.0RC1', '>=')) {

        // PHP 5.4 ternary operator performance was optimized
        $compiler
          ->raw('(isset($context[')
          ->string($name)
          ->raw(']) ? $context[')
          ->string($name)
          ->raw('] : ');
        if ($this
          ->getAttribute('ignore_strict_check') || !$compiler
          ->getEnvironment()
          ->isStrictVariables()) {
          $compiler
            ->raw('null)');
        }
        else {
          $compiler
            ->raw('$this->getContext($context, ')
            ->string($name)
            ->raw('))');
        }
      }
      else {
        $compiler
          ->raw('$this->getContext($context, ')
          ->string($name);
        if ($this
          ->getAttribute('ignore_strict_check')) {
          $compiler
            ->raw(', true');
        }
        $compiler
          ->raw(')');
      }
    }
  }
  public function isSpecial() {
    return isset($this->specialVars[$this
      ->getAttribute('name')]);
  }
  public function isSimple() {
    return !$this
      ->isSpecial() && !$this
      ->getAttribute('is_defined_test');
  }

}