[String] add LazyString to provide memoizing stringable objects

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -112,6 +112,7 @@
 use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
 use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
 use Symfony\Component\Stopwatch\Stopwatch;
+use Symfony\Component\String\LazyString;
 use Symfony\Component\String\Slugger\SluggerInterface;
 use Symfony\Component\Translation\Command\XliffLintCommand as BaseXliffLintCommand;
 use Symfony\Component\Translation\Translator;
@@ -1390,9 +1391,15 @@ private function registerSecretsConfiguration(array $config, ContainerBuilder $c
                 throw new InvalidArgumentException(sprintf('Invalid value "%s" set as "decryption_env_var": only "word" characters are allowed.', $config['decryption_env_var']));
             }
 
-            $container->getDefinition('secrets.vault')->replaceArgument(1, "%env({$config['decryption_env_var']})%");
+            if (class_exists(LazyString::class)) {
+                $container->getDefinition('secrets.decryption_key')->replaceArgument(1, $config['decryption_env_var']);
+            } else {
+                $container->getDefinition('secrets.vault')->replaceArgument(1, "%env({$config['decryption_env_var']})%");
+                $container->removeDefinition('secrets.decryption_key');
+            }
         } else {
             $container->getDefinition('secrets.vault')->replaceArgument(1, null);
+            $container->removeDefinition('secrets.decryption_key');
         }
     }
 

src/Symfony/Bundle/FrameworkBundle/Resources/config/secrets.xml

@@ -8,6 +8,10 @@
         <service id="secrets.vault" class="Symfony\Bundle\FrameworkBundle\Secrets\SodiumVault">
             <tag name="container.env_var_loader" />
             <argument />
+            <argument type="service" id="secrets.decryption_key" on-invalid="ignore" />
+        </service>
+
+        <service id="secrets.decryption_key" parent="getenv">
             <argument />
         </service>
 

src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml

@@ -129,5 +129,19 @@
             <tag name="kernel.locale_aware" />
         </service>
         <service id="Symfony\Component\String\Slugger\SluggerInterface" alias="slugger" />
+
+        <!-- inherit from this service to lazily access env vars -->
+        <service id="getenv" class="Symfony\Component\String\LazyString" abstract="true">
+            <factory class="Symfony\Component\String\LazyString" method="fromCallable" />
+            <argument type="service">
+                <service class="Closure">
+                    <factory class="Closure" method="fromCallable" />
+                    <argument type="collection">
+                        <argument type="service" id="service_container" />
+                        <argument>getEnv</argument>
+                    </argument>
+                </service>
+            </argument>
+        </service>
     </services>
 </container>

src/Symfony/Component/String/CHANGELOG.md

@@ -4,8 +4,9 @@ CHANGELOG
 5.1.0
 -----
 
- * Added the `AbstractString::reverse()` method.
- * Made `AbstractString::width()` follow POSIX.1-2001.
+ * added the `AbstractString::reverse()` method
+ * made `AbstractString::width()` follow POSIX.1-2001
+ * added `LazyString` which provides memoizing stringable objects
 
 5.0.0
 -----

src/Symfony/Component/String/LazyString.php

@@ -0,0 +1,165 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\String;
+
+/**
+ * A string whose value is computed lazily by a callback.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class LazyString implements \JsonSerializable
+{
+    private $value;
+
+    /**
+     * @param callable|array $callback A callable or a [Closure, method] lazy-callable
+     *
+     * @return static
+     */
+    public static function fromCallable($callback, ...$arguments): self
+    {
+        if (!\is_callable($callback) && !(\is_array($callback) && isset($callback[0]) && $callback[0] instanceof \Closure && 2 >= \count($callback))) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be a callable or a [Closure, method] lazy-callable, %s given.', __METHOD__, \gettype($callback)));
+        }
+
+        $lazyString = new static();
+        $lazyString->value = static function () use (&$callback, &$arguments, &$value): string {
+            if (null !== $arguments) {
+                if (!\is_callable($callback)) {
+                    $callback[0] = $callback[0]();
+                    $callback[1] = $callback[1] ?? '__invoke';
+                }
+                $value = $callback(...$arguments);
+                $callback = self::getPrettyName($callback);
+                $arguments = null;
+            }
+
+            return $value ?? '';
+        };
+
+        return $lazyString;
+    }
+
+    /**
+     * @param object|string|int|float|bool $value A scalar or an object that implements the __toString() magic method
+     *
+     * @return static
+     */
+    public static function fromStringable($value): self
+    {
+        if (!self::isStringable($value)) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be a scalar or an object that implements the __toString() magic method, %s given.', __METHOD__, \is_object($value) ? \get_class($value) : \gettype($value)));
+        }
+
+        if (\is_object($value)) {
+            return static::fromCallable([$value, '__toString']);
+        }
+
+        $lazyString = new static();
+        $lazyString->value = (string) $value;
+
+        return $lazyString;
+    }
+
+    /**
+     * Tells whether the provided value can be cast to string.
+     */
+    final public static function isStringable($value): bool
+    {
+        return \is_string($value) || $value instanceof self || (\is_object($value) ? \is_callable([$value, '__toString']) : is_scalar($value));
+    }
+
+    /**
+     * Casts scalars and stringable objects to strings.
+     *
+     * @param object|string|int|float|bool $value
+     *
+     * @throws \TypeError When the provided value is not stringable
+     */
+    final public static function resolve($value): string
+    {
+        return $value;
+    }
+
+    public function __toString()
+    {
+        if (\is_string($this->value)) {
+            return $this->value;
+        }
+
+        try {
+            return $this->value = ($this->value)();
+        } catch (\Throwable $e) {
+            if (\TypeError::class === \get_class($e) && __FILE__ === $e->getFile()) {
+                $type = explode(', ', $e->getMessage());
+                $type = substr(array_pop($type), 0, -\strlen(' returned'));
+                $r = new \ReflectionFunction($this->value);
+                $callback = $r->getStaticVariables()['callback'];
+
+                $e = new \TypeError(sprintf('Return value of %s() passed to %s::fromCallable() must be of the type string, %s returned.', $callback, static::class, $type));
+            }
+
+            if (\PHP_VERSION_ID < 70400) {
+                // leverage the ErrorHandler component with graceful fallback when it's not available
+                return trigger_error($e, E_USER_ERROR);
+            }
+
+            throw $e;
+        }
+    }
+
+    public function __sleep(): array
+    {
+        $this->__toString();
+
+        return ['value'];
+    }
+
+    public function jsonSerialize(): string
+    {
+        return $this->__toString();
+    }
+
+    private function __construct()
+    {
+    }
+
+    private static function getPrettyName(callable $callback): string
+    {
+        if (\is_string($callback)) {
+            return $callback;
+        }
+
+        if (\is_array($callback)) {
+            $class = \is_object($callback[0]) ? \get_class($callback[0]) : $callback[0];
+            $method = $callback[1];
+        } elseif ($callback instanceof \Closure) {
+            $r = new \ReflectionFunction($callback);
+
+            if (false !== strpos($r->name, '{closure}') || !$class = $r->getClosureScopeClass()) {
+                return $r->name;
+            }
+
+            $class = $class->name;
+            $method = $r->name;
+        } else {
+            $class = \get_class($callback);
+            $method = '__invoke';
+        }
+
+        if (isset($class[15]) && "\0" === $class[15] && 0 === strpos($class, "class@anonymous\x00")) {
+            $class = (get_parent_class($class) ?: key(class_implements($class))).'@anonymous';
+        }
+
+        return $class.'::'.$method;
+    }
+}

src/Symfony/Component/String/Tests/LazyStringTest.php

@@ -0,0 +1,112 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\String\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\ErrorHandler\ErrorHandler;
+use Symfony\Component\String\LazyString;
+
+class LazyStringTest extends TestCase
+{
+    public function testLazyString()
+    {
+        $count = 0;
+        $s = LazyString::fromCallable(function () use (&$count) {
+            return ++$count;
+        });
+
+        $this->assertSame(0, $count);
+        $this->assertSame('1', (string) $s);
+        $this->assertSame(1, $count);
+    }
+
+    public function testLazyCallable()
+    {
+        $count = 0;
+        $s = LazyString::fromCallable([function () use (&$count) {
+            return new class($count) {
+                private $count;
+
+                public function __construct(int &$count)
+                {
+                    $this->count = &$count;
+                }
+
+                public function __invoke()
+                {
+                    return ++$this->count;
+                }
+            };
+        }]);
+
+        $this->assertSame(0, $count);
+        $this->assertSame('1', (string) $s);
+        $this->assertSame(1, $count);
+        $this->assertSame('1', (string) $s); // ensure the value is memoized
+        $this->assertSame(1, $count);
+    }
+
+    /**
+     * @runInSeparateProcess
+     */
+    public function testReturnTypeError()
+    {
+        ErrorHandler::register();
+
+        $s = LazyString::fromCallable(function () { return []; });
+
+        $this->expectException(\TypeError::class);
+        $this->expectExceptionMessage('Return value of '.__NAMESPACE__.'\{closure}() passed to '.LazyString::class.'::fromCallable() must be of the type string, array returned.');
+
+        (string) $s;
+    }
+
+    public function testFromStringable()
+    {
+        $this->assertInstanceOf(LazyString::class, LazyString::fromStringable('abc'));
+        $this->assertSame('abc', (string) LazyString::fromStringable('abc'));
+        $this->assertSame('1', (string) LazyString::fromStringable(true));
+        $this->assertSame('', (string) LazyString::fromStringable(false));
+        $this->assertSame('123', (string) LazyString::fromStringable(123));
+        $this->assertSame('123.456', (string) LazyString::fromStringable(123.456));
+        $this->assertStringContainsString('hello', (string) LazyString::fromStringable(new \Exception('hello')));
+    }
+
+    public function testResolve()
+    {
+        $this->assertSame('abc', LazyString::resolve('abc'));
+        $this->assertSame('1', LazyString::resolve(true));
+        $this->assertSame('', LazyString::resolve(false));
+        $this->assertSame('123', LazyString::resolve(123));
+        $this->assertSame('123.456', LazyString::resolve(123.456));
+        $this->assertStringContainsString('hello', LazyString::resolve(new \Exception('hello')));
+    }
+
+    public function testIsStringable()
+    {
+        $this->assertTrue(LazyString::isStringable('abc'));
+        $this->assertTrue(LazyString::isStringable(true));
+        $this->assertTrue(LazyString::isStringable(false));
+        $this->assertTrue(LazyString::isStringable(123));
+        $this->assertTrue(LazyString::isStringable(123.456));
+        $this->assertTrue(LazyString::isStringable(new \Exception('hello')));
+    }
+
+    public function testIsNotStringable()
+    {
+        $this->assertFalse(LazyString::isStringable(null));
+        $this->assertFalse(LazyString::isStringable([]));
+        $this->assertFalse(LazyString::isStringable(STDIN));
+        $this->assertFalse(LazyString::isStringable(new \StdClass()));
+        $this->assertFalse(LazyString::isStringable(@eval('return new class() {private function __toString() {}};')));
+    }
+}

src/Symfony/Component/String/composer.json

@@ -23,6 +23,7 @@
         "symfony/translation-contracts": "^1.1|^2"
     },
     "require-dev": {
+        "symfony/error-handler": "^4.4|^5.0",
         "symfony/http-client": "^4.4|^5.0",
         "symfony/var-exporter": "^4.4|^5.0"
     },