symfony/src/Symfony/Bundle/TwigBundle/Resources/config/twig.xml

<?xml version="1.0" ?>

<container xmlns="http://www.symfony-project.org/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.symfony-project.org/schema/dic/services http://www.symfony-project.org/schema/dic/services/services-1.0.xsd">

    <parameters>
        <parameter key="twig.class">Twig_Environment</parameter>
        <parameter key="twig.options" type="collection">
            <parameter key="charset">%kernel.charset%</parameter>
            <parameter key="debug">%kernel.debug%</parameter>
            <parameter key="cache">%kernel.cache_dir%/twig</parameter>
        </parameter>
        <parameter key="twig.loader.class">Symfony\Bundle\TwigBundle\Loader\Loader</parameter>
        <parameter key="twig.renderer.class">Symfony\Bundle\TwigBundle\Renderer\Renderer</parameter>
        <parameter key="twig.form.resources" type="collection">
            <parameter>TwigBundle::form.twig</parameter>
        </parameter>
    </parameters>

    <services>
        <service id="twig" class="%twig.class%">
            <argument type="service" id="twig.loader" />
            <argument>%twig.options%</argument>
        </service>

        <service id="twig.loader" class="%twig.loader.class%">
            <argument type="service" id="templating.name_converter" />
            <argument type="service" id="templating.loader" />
        </service>

        <service id="twig.renderer" class="%twig.renderer.class%">
            <tag name="templating.renderer" alias="twig" />
            <argument type="service" id="twig" />
        </service>

        <service id="twig.extension.trans" class="Symfony\Bundle\TwigBundle\Extension\TransExtension" public="false">
            <tag name="twig.extension" />
            <argument type="service" id="translator" />
        </service>

        <service id="twig.extension.helpers" class="Symfony\Bundle\TwigBundle\Extension\TemplatingExtension" public="false">
            <tag name="twig.extension" />
            <argument type="service" id="service_container" />
        </service>

        <service id="twig.extension.form" class="Symfony\Bundle\TwigBundle\Extension\FormExtension" public="false">
            <tag name="twig.extension" />
            <argument>%twig.form.resources%</argument>
        </service>

        <service id="twig.security.form" class="Symfony\Bundle\TwigBundle\Extension\SecurityExtension" public="false">
            <tag name="twig.extension" />
            <argument type="service" id="security.context" on-invalid="ignore" />
        </service>
    </services>
</container>