}

    /**
     * Registers a Function.
     *
     * @param string|TwigFunction                  $name     The function name or a \Twig_SimpleFunction instance
     * @param \Twig_FunctionInterface|TwigFunction $function
     */
    public function addFunction($name, $function = null)
    {
        if (!$name instanceof TwigFunction && !($function instanceof TwigFunction || $function instanceof \Twig_FunctionInterface)) {
            throw new \LogicException('A function must be an instance of \Twig_FunctionInterface or \Twig_SimpleFunction.');
        }

        if ($name instanceof TwigFunction) {
            $function = $name;
            $name = $function->getName();
        } else {
            @trigger_error(sprintf('Passing a name as a first argument to the %s method is deprecated since version 1.21. Pass an instance of "Twig_SimpleFunction" instead when defining function "%s".', __METHOD__, $name), \E_USER_DEPRECATED);
        }

        if ($this->extensionInitialized) {
            throw new \LogicException(sprintf('Unable to add function "%s" as extensions have already been initialized.', $name));
        }

        $this->staging->addFunction($name, $function);
    }

    /**
     * Get a function by name.
     *
     * Subclasses may override this method and load functions differently;
     * so no list of functions is available.
     *
     * @param string $name function name
     *
     * @return \Twig_Function|false
     *
     * @internal
     */
    public function getFunction($name)
    {
        if (!$this->extensionInitialized) {
            $this->initExtensions();
        }

        if (isset($this->functions[$name])) {
            return $this->functions[$name];
        }

        foreach ($this->functions as $pattern => $function) {
            $pattern = str_replace('\\*', '(.*?)', preg_quote($pattern, '#'), $count);

            if ($count) {
                if (preg_match('#^'.$pattern.'$#', $name, $matches)) {
                    array_shift($matches);
                    $function->setArguments($matches);

                    return $function;
                }
            }
        }

        foreach ($this->functionCallbacks as $callback) {
            if (false !== $function = \call_user_func($callback, $name)) {
                return $function;
            }
        }

        return false;
    }

    public function registerUndefinedFunctionCallback($callable)
    {
        $this->functionCallbacks[] = $callable;
    }

    /**
     * Gets registered functions.
     *
     * Be warned that this method cannot return functions defined with registerUndefinedFunctionCallback.
     *
     * @return \Twig_FunctionInterface[]
     *
     * @see registerUndefinedFunctionCallback
     *
     * @internal
     */
    public function getFunctions()
    {
        if (!$this->extensionInitialized) {
            $this->initExtensions();
        }

        return $this->functions;
    }

    /**
     * Registers a Global.
     *
     * New globals can be added before compiling or rendering a template;
     * but after, you can only update existing globals.
     *
     * @param string $name  The global name
     * @param mixed  $value The global value
     */
    public function addGlobal($name, $value)
    {
        if ($this->extensionInitialized || $this->runtimeInitialized) {
            if (null === $this->globals) {
                $this->globals = $this->initGlobals();
            }

            if (!\array_key_exists($name, $this->globals)) {
                // The deprecation notice must be turned into the following exception in Twig 2.0
                @trigger_error(sprintf('Registering global variable "%s" at runtime or when the extensions have already been initialized is deprecated since version 1.21.', $name), \E_USER_DEPRECATED);
                //throw new \LogicException(sprintf('Unable to add global "%s" as the runtime or the extensions have already been initialized.', $name));
            }
        }

        if ($this->extensionInitialized || $this->runtimeInitialized) {
            // update the value
            $this->globals[$name] = $value;
        } else {
            $this->staging->addGlobal($name, $value);
        }
    }

    /**
     * Gets the registered Globals.
     *
     * @return array An array of globals
     *
     * @internal
     */
    public function getGlobals()
    {
        if (!$this->runtimeInitialized && !$this->extensionInitialized) {
            return $this->initGlobals();
        }

        if (null === $this->globals) {
            $this->globals = $this->initGlobals();
        }

        return $this->globals;
    }

    /**
     * Merges a context with the defined globals.
     *
     * @param array $context An array representing the context
     *
     * @return array The context merged with the globals
     */
    public function mergeGlobals(array $context)
    {
        // we don't use array_merge as the context being generally
        // bigger than globals, this code is faster.
        foreach ($this->getGlobals() as $key => $value) {
            if (!\array_key_exists($key, $context)) {
                $context[$key] = $value;
            }
        }

        return $context;
    }

    /**
     * Gets the registered unary Operators.
     *
     * @return array An array of unary operators
     *
     * @internal
     */
    public function getUnaryOperators()
    {
        if (!$this->extensionInitialized) {
            $this->initExtensions();
        }

        return $this->unaryOperators;
    }

    /**
     * Gets the registered binary Operators.
     *
     * @return array An array of binary operators
     *
     * @internal
     */
    public function getBinaryOperators()
    {
        if (!$this->extensionInitialized) {
            $this->initExtensions();
        }

        return $this->binaryOperators;
    }

    /**
     * @deprecated since 1.23 (to be removed in 2.0)
     */
    public function computeAlternatives($name, $items)
    {
        @trigger_error(sprintf('The %s method is deprecated since version 1.23 and will be removed in Twig 2.0.', __METHOD__), \E_USER_DEPRECATED);

        return SyntaxError::computeAlternatives($name, $items);
    }

    /**
     * @internal
     */
    protected function initGlobals()
    {
        $globals = [];
        foreach ($this->extensions as $name => $extension) {
            if (!$extension instanceof GlobalsInterface) {
                $m = new \ReflectionMethod($extension, 'getGlobals');

                $parentClass = $m->getDeclaringClass()->getName();
                if ('Twig_Extension' !== $parentClass && 'Twig\Extension\AbstractExtension' !== $parentClass) {
                    @trigger_error(sprintf('Defining the getGlobals() method in the "%s" extension without explicitly implementing Twig\Extension\GlobalsInterface is deprecated since version 1.23.', $name), \E_USER_DEPRECATED);
                }
            }

            $extGlob = $extension->getGlobals();
            if (!\is_array($extGlob)) {
                throw new \UnexpectedValueException(sprintf('"%s::getGlobals()" must return an array of globals.', \get_class($extension)));
            }

            $globals[] = $extGlob;
        }

        $globals[] = $this->staging->getGlobals();

        return \call_user_func_array('array_merge', $globals);
    }

    /**
     * @internal
     */
    protected function initExtensions()
    {
        if ($this->extensionInitialized) {
            return;
        }

        $this->parsers = new \Twig_TokenParserBroker([], [], false);
        $this->filters = [];
        $this->functions = [];
        $this->tests = [];
        $this->visitors = [];
        $this->unaryOperators = [];
        $this->binaryOperators = [];

        foreach ($this->extensions as $extension) {
            $this->initExtension($extension);
        }
        $this->initExtension($this->staging);
        // Done at the end only, so that an exception during initialization does not mark the environment as initialized when catching the exception
        $this->extensionInitialized = true;
    }

    /**
     * @internal
     */
    protected function initExtension(ExtensionInterface $extension)
    {
        // filters
        foreach ($extension->getFilters() as $name => $filter) {
            if ($filter instanceof TwigFilter) {
                $name = $filter->getName();
            } else {
                @trigger_error(sprintf('Using an instance of "%s" for filter "%s" is deprecated since version 1.21. Use \Twig_SimpleFilter instead.', \get_class($filter), $name), \E_USER_DEPRECATED);
            }

            $this->filters[$name] = $filter;
        }

        // functions
        foreach ($extension->getFunctions() as $name => $function) {
            if ($function instanceof TwigFunction) {
                $name = $function->getName();
            } else {
                @trigger_error(sprintf('Using an instance of "%s" for function "%s" is deprecated since version 1.21. Use \Twig_SimpleFunction instead.', \get_class($function), $name), \E_USER_DEPRECATED);
            }

            $this->functions[$name] = $function;
        }

        // tests
        foreach ($extension->getTests() as $name => $test) {
            if ($test instanceof TwigTest) {
                $name = $test->getName();
            } else {
                @trigger_error(sprintf('Using an instance of "%s" for test "%s" is deprecated since version 1.21. Use \Twig_SimpleTest instead.', \get_class($test), $name), \E_USER_DEPRECATED);
            }

            $this->tests[$name] = $test;
        }

        // token parsers
        foreach ($extension->getTokenParsers() as $parser) {
            if ($parser instanceof TokenParserInterface) {
                $this->parsers->addTokenParser($parser);
            } elseif ($parser instanceof \Twig_TokenParserBrokerInterface) {
                @trigger_error('Registering a \Twig_TokenParserBrokerInterface instance is deprecated since version 1.21.', \E_USER_DEPRECATED);

                $this->parsers->addTokenParserBroker($parser);
            } else {
                throw new \LogicException('getTokenParsers() must return an array of \Twig_TokenParserInterface or \Twig_TokenParserBrokerInterface instances.');
            }
        }

        // node visitors
        foreach ($extension->getNodeVisitors() as $visitor) {
            $this->visitors[] = $visitor;
        }

        // operators
        if ($operators = $extension->getOperators()) {
            if (!\is_array($operators)) {
                throw new \InvalidArgumentException(sprintf('"%s::getOperators()" must return an array with operators, got "%s".', \get_class($extension), \is_object($operators) ? \get_class($operators) : \gettype($operators).(\is_resource($operators) ? '' : '#'.$operators)));
            }

            if (2 !== \count($operators)) {
                throw new \InvalidArgumentException(sprintf('"%s::getOperators()" must return an array of 2 elements, got %d.', \get_class($extension), \count($operators)));
            }

            $this->unaryOperators = array_merge($this->unaryOperators, $operators[0]);
            $this->binaryOperators = array_merge($this->binaryOperators, $operators[1]);
        }
    }

    /**
     * @deprecated since 1.22 (to be removed in 2.0)
     */
    protected function writeCacheFile($file, $content)
    {
        $this->cache->write($file, $content);
    }

    private function updateOptionsHash()
    {
        $hashParts = array_merge(
            array_keys($this->extensions),
            [
                (int) \function_exists('twig_template_get_attributes'),
                \PHP_MAJOR_VERSION,
                \PHP_MINOR_VERSION,
                self::VERSION,
                (int) $this->debug,
                $this->baseTemplateClass,
                (int) $this->strictVariables,
            ]
        );
        $this->optionsHash = implode(':', $hashParts);
    }
}

class_alias('Twig\Environment', 'Twig_Environment');