[Validator] Extracted message interpolation logic of ConstraintViolation and used the Translation component for that
[Form] Adapted Form component to translator integration in the validator
[TwigBridge] Adapted TwigBridge to translator integration in the validator
[FrameworkBundle] Adapted FrameworkBundle to translator integration in the validator
[DoctrineBridge] Adapted DoctrineBridge to translator integration in the validator
[Form] Added upgrade instructions to the UPGRADE file
[Form][Validator] Added BC breaks in unstable code to the CHANGELOG
[Validator] Changed validator to support pluralized messages by default

This was implemented in order to satisfy Drupal's requirements for a
singular and a plural message whenever a message is passed to their
implementation of transChoice().
[Validator] Fixed failing test
[Validator] Added ExceptionInterface, BadMethodCallException and InvalidArgumentException
[Validator] Improved the inline documentation of DefaultTranslator
[Validator] Changed DefaultTranslator::getLocale() to always return 'en'
merged branch bschussek/issue5844 (PR #6137)

This PR was merged into the master branch.

Commits
-------

586a16e [Validator] Changed DefaultTranslator::getLocale() to always return 'en'
58bfd60 [Validator] Improved the inline documentation of DefaultTranslator
cd662cc [Validator] Added ExceptionInterface, BadMethodCallException and InvalidArgumentException
e00e5ec [Validator] Fixed failing test
cc0df0a [Validator] Changed validator to support pluralized messages by default
56d61eb [Form][Validator] Added BC breaks in unstable code to the CHANGELOG
1e34e91 [Form] Added upgrade instructions to the UPGRADE file
b94a256 [DoctrineBridge] Adapted DoctrineBridge to translator integration in the validator
c96a051 [FrameworkBundle] Adapted FrameworkBundle to translator integration in the validator
92a3b27 [TwigBridge] Adapted TwigBridge to translator integration in the validator
e7eb5b0 [Form] Adapted Form component to translator integration in the validator
46f751c [Validator] Extracted message interpolation logic of ConstraintViolation and used the Translation component for that

Discussion
----------

[Validator] Integrated the Translator in the Validator component

Bug fix: no
Feature addition: no
Backwards compatibility break: yes
Symfony2 tests pass: yes
Fixes the following tickets: #5844, #6117
Todo: -
License of the code: MIT
Documentation PR: -

This PR allows to replace the default message substitution strategy in the validator (`strtr()`) by passing an implementation of `Symfony\Component\Translation\TranslatorInterface`. The motivation for this are both #5844 and the need to replace the translation strategy in Drupal's integration of the Validator.

In the stand-alone usage of the validator, both the translator and the default translation domain can now be passed to `ValidatorBuilderInterface`:

```php
$validator = Validation::createValidatorBuilder()
    ->setTranslator(new MyTranslator())
    ->setTranslationDomain('validators')
    ->getValidator();
```

References:

* #5844
* #6117
* #6129
* [Add a validation framework to Drupal 8](http://drupal.org/node/1845546)
* [Add the symfony validator component to core despite Symfony potentially releasing BC-breaking updates after 2.3.](http://drupal.org/node/1849564)

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by Tobion at 2012-11-28T08:53:25Z

no BC break? Looking at ValidatorBuilderInterface there is definitely one.

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by bschussek at 2012-11-28T08:55:01Z

ValidatorBuilderInterface is not part of the stable API. You are not supposed to implement this interface.

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by Tobion at 2012-11-28T09:01:07Z

We're not only documenting bc breaks for stable API, otherwise we could remove 90% of the upgrade file since few methods are tagged with API.
An interface that nobody should implement?

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by bschussek at 2012-11-28T09:30:02Z

The question is what to consider a BC break. Something will always break for someone. Should we consequently mark everything as BC break? I don't think so.

For example, since 2.1, you are supposed to use `Validation::createValidator*()` for creating a validator. Because of that, I won't consider changing the constructor signature of `Validator` a BC break anymore from 2.1 on.

The same for the unstable interfaces. These are currently meant to be used only, that is, type hint against them and call their methods. But we don't guarantee that we won't add methods to them.

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by Tobion at 2012-11-28T09:38:19Z

I agree that almost any change could be considered a BC break. So we probably need to better define what a BC break is and what not. Otherwise Symfony will stop evolving after 2.3 because from then on Fabien wanted to prevent BC breaks which is almost impossible in a strict definition of bc break.

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by fabpot at 2012-11-28T11:37:22Z

BC breaks should always be documented, and we guarantee BC only for things tagged with @api. I'm going to update the docs to make things clearer.

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by bschussek at 2012-11-28T13:09:57Z

@fabpot I documented these changes now in the CHANGELOG: af99ebb1206ac92889b7193ba1ecc12bf2617e85

Are we sure we want to document *all* BC breaks from now on, even in non-@api code? This could rather scare people looking at our changelogs (lots of BC BREAKS there).

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by fago at 2012-11-28T17:29:58Z

Unfortunately, it turns out the symfony translator interface does not mach the Drupal translation system as well as we initally thought, see http://drupal.org/node/1852106. Given that, this would integrating the validator component into Drupal even harder, because it introduces the dependency on the (unwanted) translation component. :(

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by stof at 2012-11-28T18:19:36Z

If this does not help Drupal anyway, maybe #5844 is a better way to manage translations for people using the validator outside forms ?
and the Drupal guys would simply follow a similar approach, but based on their own translator instead of the symfony one.

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by fago at 2012-11-28T18:50:12Z

Yeah. The only problem I see with the approach of #5844 is that *after* validation only the translated messages are available. We'd need to have access to the untranslated messages also.

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by fago at 2012-11-29T09:49:47Z

As our translation system handles translating pluralized messages differently, the current ExecutionContextInterface::addViolation() method poses a problem also. We need to pass on - both the single and plural - message, as the message gets chosen during translation, see http://api.drupal.org/api/drupal/core!includes!common.inc/function/format_plural/8
So maybe, we could allow adding an already created ConstraintViolation object also? Then, we could implement a "PluralConstraintViolation" class that takes both message templates.

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by bschussek at 2012-12-03T15:52:36Z

I updated this PR to support pluralized messages by default in the validator. This should solve the problem of the Drupal guys, because their implementation of `TranslatorInterface::transChoice($id, $number, ...)` can now simply split the $id by pipes (`|`) and pass the parts to their own `format_plural($count, $singular, $plural, ...)` function.

For us, it breaks BC because translation catalog sources had to be adapted.

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by fabpot at 2012-12-03T16:25:52Z

Most of the XLF files are broken (the end is missing now).

IIUC, we now have a hard dependency on the Translation component, which is something we wanted to avoid.

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by fabpot at 2012-12-03T16:27:56Z

Oops, clicked on the "comment" button too fast.

So, the dependency is hard (you need to install the dep) but light as we only rely on the translation interface from the component (when using the default translator). It looks acceptable to me, especially because we now use Composer to manage dependencies.

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by bschussek at 2012-12-03T16:54:10Z

@fabpot Thanks for the hint. Going to fix this.

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by bschussek at 2012-12-04T11:34:43Z

@fabpot Fixed.

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by bschussek at 2012-12-07T12:40:24Z

Is there anything missing for this PR to be merged?