respect-validation/library/Rules/Sf.php

<?php
namespace Respect\Validation\Rules;

use ReflectionClass;
use ReflectionException;
use Respect\Validation\Exceptions\ComponentException;
use Symfony\Component\Validator\Validation;
use Symfony\Component\Validator\Constraint;

class Sf extends AbstractRule
{
    const SYMFONY_CONSTRAINT_NAMESPACE = 'Symfony\Component\Validator\Constraints\%s';
    public $name;
    private $constraint;

    public function __construct($name, $params = array())
    {
        $this->name = ucfirst($name);
        $this->constraint = $this->createSymfonyConstraint($this->name, $params);
    }

    private function createSymfonyConstraint($constraintName, $constraintConstructorParameters = array())
    {
        $fullClassName = sprintf(self::SYMFONY_CONSTRAINT_NAMESPACE, $constraintName);
        try {
            $constraintReflection = new ReflectionClass($fullClassName);
        } catch (ReflectionException $previousException) {
            $baseExceptionMessage = 'Symfony/Validator constraint "%s" does not exist.';
            $exceptionMessage = sprintf($baseExceptionMessage, $constraintName);
            throw new ComponentException($exceptionMessage, 0, $previousException);
        }
        if ($constraintReflection->hasMethod('__construct')) {
            return $constraintReflection->newInstanceArgs($constraintConstructorParameters);
        }

        return $constraintReflection->newInstance();
    }

    private function returnViolationsForConstraint($valueToValidate, Constraint $symfonyConstraint)
    {
        $validator = Validation::createValidator(); // You gotta love those Symfony namings
        return $validator->validateValue($valueToValidate, $symfonyConstraint);
    }

    public function assert($input)
    {
        $violations = $this->returnViolationsForConstraint($input, $this->constraint);
        if (count($violations) == 0) {
            return true;
        }

        throw $this->reportError((string) $violations);
    }

    public function validate($input)
    {
        $violations = $this->returnViolationsForConstraint($input, $this->constraint);
        if (count($violations)) {
            return false;
        }

        return true;
    }
}