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nicolas-grekasnicolas-grekas
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[String] add LazyString to provide generic stringable objects
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4 files changed

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‎CHANGELOG.md‎

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@@ -4,8 +4,9 @@ CHANGELOG
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5.1.0
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-----
66

7-
* Added the `AbstractString::reverse()` method.
8-
* Made `AbstractString::width()` follow POSIX.1-2001.
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* added the `AbstractString::reverse()` method
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* made `AbstractString::width()` follow POSIX.1-2001
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* added `LazyString` which provides memoizing stringable objects
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5.0.0
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-----

‎LazyString.php‎

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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\String;
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/**
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* A string whose value is computed lazily by a callback.
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*
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* @author Nicolas Grekas <p@tchwork.com>
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*/
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class LazyString implements \JsonSerializable
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{
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private $value;
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/**
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* @param callable|array $callback A callable or a [Closure, method] lazy-callable
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*
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* @return static
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*/
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public static function fromCallable($callback, ...$arguments): self
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{
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if (!\is_callable($callback) && !(\is_array($callback) && isset($callback[0]) && $callback[0] instanceof \Closure && 2 >= \count($callback))) {
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throw new \TypeError(sprintf('Argument 1 passed to %s() must be a callable or a [Closure, method] lazy-callable, %s given.', __METHOD__, \gettype($callback)));
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}
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$lazyString = new static();
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$lazyString->value = static function () use (&$callback, &$arguments, &$value): string {
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if (null !== $arguments) {
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if (!\is_callable($callback)) {
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$callback[0] = $callback[0]();
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$callback[1] = $callback[1] ?? '__invoke';
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}
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$value = $callback(...$arguments);
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$callback = self::getPrettyName($callback);
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$arguments = null;
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}
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return $value ?? '';
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};
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return $lazyString;
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}
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/**
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* @param object|string|int|float|bool $value A scalar or an object that implements the __toString() magic method
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*
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* @return static
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*/
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public static function fromStringable($value): self
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{
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if (!self::isStringable($value)) {
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throw new \TypeError(sprintf('Argument 1 passed to %s() must be a scalar or an object that implements the __toString() magic method, %s given.', __METHOD__, \is_object($value) ? \get_class($value) : \gettype($value)));
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}
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if (\is_object($value)) {
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return static::fromCallable([$value, '__toString']);
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}
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$lazyString = new static();
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$lazyString->value = (string) $value;
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return $lazyString;
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}
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/**
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* Tells whether the provided value can be cast to string.
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*/
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final public static function isStringable($value): bool
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{
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return \is_string($value) || $value instanceof self || (\is_object($value) ? \is_callable([$value, '__toString']) : is_scalar($value));
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}
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/**
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* Casts scalars and stringable objects to strings.
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*
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* @param object|string|int|float|bool $value
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*
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* @throws \TypeError When the provided value is not stringable
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*/
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final public static function resolve($value): string
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{
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return $value;
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}
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public function __toString()
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{
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if (\is_string($this->value)) {
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return $this->value;
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}
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try {
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return $this->value = ($this->value)();
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} catch (\Throwable $e) {
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if (\TypeError::class === \get_class($e) && __FILE__ === $e->getFile()) {
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$type = explode(', ', $e->getMessage());
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$type = substr(array_pop($type), 0, -\strlen(' returned'));
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$r = new \ReflectionFunction($this->value);
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$callback = $r->getStaticVariables()['callback'];
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$e = new \TypeError(sprintf('Return value of %s() passed to %s::fromCallable() must be of the type string, %s returned.', $callback, static::class, $type));
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}
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if (\PHP_VERSION_ID < 70400) {
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// leverage the ErrorHandler component with graceful fallback when it's not available
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return trigger_error($e, E_USER_ERROR);
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}
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throw $e;
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}
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}
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public function __sleep(): array
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{
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$this->__toString();
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return ['value'];
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}
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public function jsonSerialize(): string
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{
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return $this->__toString();
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}
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private function __construct()
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{
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}
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private static function getPrettyName(callable $callback): string
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{
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if (\is_string($callback)) {
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return $callback;
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}
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if (\is_array($callback)) {
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$class = \is_object($callback[0]) ? \get_class($callback[0]) : $callback[0];
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$method = $callback[1];
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} elseif ($callback instanceof \Closure) {
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$r = new \ReflectionFunction($callback);
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if (false !== strpos($r->name, '{closure}') || !$class = $r->getClosureScopeClass()) {
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return $r->name;
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}
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$class = $class->name;
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$method = $r->name;
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} else {
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$class = \get_class($callback);
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$method = '__invoke';
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}
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if (isset($class[15]) && "\0" === $class[15] && 0 === strpos($class, "class@anonymous\x00")) {
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$class = (get_parent_class($class) ?: key(class_implements($class))).'@anonymous';
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}
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return $class.'::'.$method;
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}
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}

‎Tests/LazyStringTest.php‎

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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\String\Tests;
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use PHPUnit\Framework\TestCase;
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use Symfony\Component\ErrorHandler\ErrorHandler;
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use Symfony\Component\String\LazyString;
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class LazyStringTest extends TestCase
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{
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public function testLazyString()
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{
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$count = 0;
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$s = LazyString::fromCallable(function () use (&$count) {
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return ++$count;
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});
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$this->assertSame(0, $count);
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$this->assertSame('1', (string) $s);
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$this->assertSame(1, $count);
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}
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public function testLazyCallable()
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{
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$count = 0;
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$s = LazyString::fromCallable([function () use (&$count) {
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return new class($count) {
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private $count;
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public function __construct(int &$count)
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{
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$this->count = &$count;
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}
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public function __invoke()
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{
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return ++$this->count;
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}
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};
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}]);
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$this->assertSame(0, $count);
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$this->assertSame('1', (string) $s);
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$this->assertSame(1, $count);
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$this->assertSame('1', (string) $s); // ensure the value is memoized
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$this->assertSame(1, $count);
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}
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/**
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* @runInSeparateProcess
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*/
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public function testReturnTypeError()
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{
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ErrorHandler::register();
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$s = LazyString::fromCallable(function () { return []; });
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$this->expectException(\TypeError::class);
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$this->expectExceptionMessage('Return value of '.__NAMESPACE__.'\{closure}() passed to '.LazyString::class.'::fromCallable() must be of the type string, array returned.');
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(string) $s;
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}
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public function testFromStringable()
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{
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$this->assertInstanceOf(LazyString::class, LazyString::fromStringable('abc'));
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$this->assertSame('abc', (string) LazyString::fromStringable('abc'));
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$this->assertSame('1', (string) LazyString::fromStringable(true));
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$this->assertSame('', (string) LazyString::fromStringable(false));
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$this->assertSame('123', (string) LazyString::fromStringable(123));
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$this->assertSame('123.456', (string) LazyString::fromStringable(123.456));
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$this->assertStringContainsString('hello', (string) LazyString::fromStringable(new \Exception('hello')));
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}
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public function testResolve()
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{
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$this->assertSame('abc', LazyString::resolve('abc'));
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$this->assertSame('1', LazyString::resolve(true));
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$this->assertSame('', LazyString::resolve(false));
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$this->assertSame('123', LazyString::resolve(123));
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$this->assertSame('123.456', LazyString::resolve(123.456));
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$this->assertStringContainsString('hello', LazyString::resolve(new \Exception('hello')));
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}
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public function testIsStringable()
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{
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$this->assertTrue(LazyString::isStringable('abc'));
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$this->assertTrue(LazyString::isStringable(true));
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$this->assertTrue(LazyString::isStringable(false));
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$this->assertTrue(LazyString::isStringable(123));
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$this->assertTrue(LazyString::isStringable(123.456));
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$this->assertTrue(LazyString::isStringable(new \Exception('hello')));
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}
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public function testIsNotStringable()
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{
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$this->assertFalse(LazyString::isStringable(null));
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$this->assertFalse(LazyString::isStringable([]));
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$this->assertFalse(LazyString::isStringable(STDIN));
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$this->assertFalse(LazyString::isStringable(new \StdClass()));
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$this->assertFalse(LazyString::isStringable(@eval('return new class() {private function __toString() {}};')));
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}
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}

‎composer.json‎

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"symfony/translation-contracts": "^1.1|^2"
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},
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"require-dev": {
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"symfony/error-handler": "^4.4|^5.0",
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"symfony/http-client": "^4.4|^5.0",
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"symfony/var-exporter": "^4.4|^5.0"
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},

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