File: vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Resources/config/validator.xml

<?xml version="1.0" ?>

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

    <parameters>
        <parameter key="validator.class">Symfony\Component\Validator\Validator\ValidatorInterface</parameter>
        <parameter key="validator.builder.class">Symfony\Component\Validator\ValidatorBuilderInterface</parameter>
        <parameter key="validator.builder.factory.class">Symfony\Component\Validator\Validation</parameter>
        <parameter key="validator.mapping.cache.apc.class">Symfony\Component\Validator\Mapping\Cache\ApcCache</parameter>
        <parameter key="validator.mapping.cache.prefix" />
        <parameter key="validator.validator_factory.class">Symfony\Bundle\FrameworkBundle\Validator\ConstraintValidatorFactory</parameter>
        <parameter key="validator.expression.class">Symfony\Component\Validator\Constraints\ExpressionValidator</parameter>
        <parameter key="validator.email.class">Symfony\Component\Validator\Constraints\EmailValidator</parameter>
    </parameters>

    <services>
        <service id="validator" class="%validator.class%">
            <factory service="validator.builder" method="getValidator" />
        </service>

        <service id="validator.builder" class="%validator.builder.class%">
            <factory class="%validator.builder.factory.class%" method="createValidatorBuilder" />
            <call method="setConstraintValidatorFactory">
                <argument type="service" id="validator.validator_factory" />
            </call>
            <call method="setTranslator">
                <argument type="service" id="translator" />
            </call>
            <call method="setTranslationDomain">
                <argument>%validator.translation_domain%</argument>
            </call>
        </service>

        <service id="validator.mapping.class_metadata_factory" alias="validator" public="false" />

        <service id="validator.mapping.cache.apc" class="%validator.mapping.cache.apc.class%" public="false">
            <argument>%validator.mapping.cache.prefix%</argument>
        </service>

        <service id="validator.mapping.cache.doctrine.apc" class="Symfony\Component\Validator\Mapping\Cache\DoctrineCache" public="false">
            <argument type="service">
                <service class="Doctrine\Common\Cache\ApcCache">
                    <call method="setNamespace">
                        <argument>%validator.mapping.cache.prefix%</argument>
                    </call>
                </service>
            </argument>
            <deprecated>The "%service_id%" service is deprecated since Symfony 2.8 and will be removed in 3.0.</deprecated>
        </service>

        <service id="validator.validator_factory" class="%validator.validator_factory.class%" public="false">
            <argument type="service" id="service_container" />
            <argument type="collection" />
        </service>

        <service id="validator.expression" class="%validator.expression.class%">
            <argument type="service" id="property_accessor" />
            <tag name="validator.constraint_validator" alias="validator.expression" />
        </service>

        <service id="validator.email" class="%validator.email.class%">
            <argument></argument>
            <tag name="validator.constraint_validator" alias="Symfony\Component\Validator\Constraints\EmailValidator" />
        </service>
    </services>
</container>