refactor: Introduce a Prefix value object

src/Configuration/Configuration.php

@@ -16,16 +16,10 @@
 
 use Humbug\PhpScoper\Configuration\Throwable\InvalidConfigurationValue;
 use Humbug\PhpScoper\Patcher\Patcher;
-use function Safe\preg_match;
 
 final class Configuration
 {
-    private const PREFIX_PATTERN = '/^[\p{L}\d_\\\\]+$/u';
-
-    /**
-     * @var non-empty-string
-     */
-    private readonly string $prefix;
+    private readonly Prefix $prefix;
 
     /**
      * @param non-empty-string|null                $path                      Absolute canonical path to the configuration file loaded.
@@ -43,15 +37,15 @@ final class Configuration
     public function __construct(
         private ?string $path,
         private ?string $outputDir,
-        string $prefix,
+        string|Prefix $prefix,
         private array $filesWithContents,
         private array $excludedFilesWithContents,
         private Patcher $patcher,
         private SymbolsConfiguration $symbolsConfiguration
     ) {
-        self::validatePrefix($prefix);
-
-        $this->prefix = $prefix;
+        $this->prefix = $prefix instanceof Prefix
+            ? $prefix
+            : new Prefix($prefix);
     }
 
     /**
@@ -93,7 +87,7 @@ public function withPrefix(string $prefix): self
      */
     public function getPrefix(): string
     {
-        return $this->prefix;
+        return $this->prefix->toString();
     }
 
     /**
@@ -150,15 +144,4 @@ public function getSymbolsConfiguration(): SymbolsConfiguration
     {
         return $this->symbolsConfiguration;
     }
-
-    private static function validatePrefix(string $prefix): void
-    {
-        if (1 !== preg_match(self::PREFIX_PATTERN, $prefix)) {
-            throw InvalidConfigurationValue::forInvalidPrefixPattern($prefix);
-        }
-
-        if (preg_match('/\\\{2,}/', $prefix)) {
-            throw InvalidConfigurationValue::forInvalidNamespaceSeparator($prefix);
-        }
-    }
 }

src/Configuration/Prefix.php

@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the humbug/php-scoper package.
+ *
+ * Copyright (c) 2017 Théo FIDRY <[email protected]>,
+ *                    Pádraic Brady <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Humbug\PhpScoper\Configuration;
+
+use Stringable;
+
+final readonly class Prefix implements Stringable
+{
+    /**
+     * @var non-empty-string
+     */
+    private string $value;
+
+    public function __construct(string $prefix)
+    {
+        PrefixValidator::validate($prefix);
+
+        $this->value = $prefix;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function __toString(): string
+    {
+        return $this->value;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function toString(): string
+    {
+        return (string) $this;
+    }
+}

src/Configuration/PrefixValidator.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the humbug/php-scoper package.
+ *
+ * Copyright (c) 2017 Théo FIDRY <[email protected]>,
+ *                    Pádraic Brady <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Humbug\PhpScoper\Configuration;
+
+use Humbug\PhpScoper\Configuration\Throwable\InvalidConfigurationValue;
+use function Safe\preg_match;
+
+final class PrefixValidator
+{
+    private const PREFIX_PATTERN = '/^[\p{L}\d_\\\\]+$/u';
+
+    /**
+     * @phpstan-assert non-empty-string $prefix
+     *
+     * @throws InvalidConfigurationValue
+     */
+    public static function validate(string $prefix): void
+    {
+        if (1 !== preg_match(self::PREFIX_PATTERN, $prefix)) {
+            throw InvalidConfigurationValue::forInvalidPrefixPattern($prefix);
+        }
+
+        if (preg_match('/\\\{2,}/', $prefix)) {
+            throw InvalidConfigurationValue::forInvalidNamespaceSeparator($prefix);
+        }
+    }
+}

tests/Configuration/ConfigurationFactoryTest.php

@@ -127,7 +127,7 @@ public function test_it_can_create_a_complete_configuration(): void
         $configuration = $this->createConfigFromStandardFile();
 
         self::assertSame($this->tmp.DIRECTORY_SEPARATOR.'scoper.inc.php', $configuration->getPath());
-        self::assertSame('MyPrefix', $configuration->getPrefix());
+        self::assertEquals(new Prefix('MyPrefix'), $configuration->getPrefix());
         self::assertSame('dist', $configuration->getOutputDir());
         self::assertSame([], $configuration->getFilesWithContents());
         self::assertSame(