Simplify modeling of the extension parts (pre-release and build)

src/Exception/InvalidIdentifierException.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Version\Exception;
+
+use DomainException;
+use Version\Extension\BaseExtension;
+
+/**
+ * @author Nikola Posa <posa.nikola@gmail.com>
+ */
+class InvalidIdentifierException extends DomainException implements ExceptionInterface
+{
+    public static function forExtensionIdentifier(BaseExtension $extension, string $identifier) : self
+    {
+        return new self(sprintf(
+            '%s identifier: %s is not valid; it must comprise only ASCII alphanumerics and hyphen',
+            get_class($extension),
+            $identifier
+        ));
+    }
+}

src/Extension/BaseExtension.php

@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Version\Extension;
+
+use Version\Exception\InvalidIdentifierException;
+
+abstract class BaseExtension
+{
+    protected const IDENTIFIERS_SEPARATOR = '.';
+
+    /**
+     * @var array
+     */
+    private $identifiers;
+
+    protected function __construct(string ...$identifiers)
+    {
+        foreach ($identifiers as $identifier) {
+            $this->validate($identifier);
+        }
+
+        $this->identifiers = $identifiers;
+    }
+
+    /**
+     * @param string $identifier
+     * @throws InvalidIdentifierException
+     * @return void
+     */
+    abstract protected function validate(string $identifier) : void;
+
+    public static function fromIdentifiers(string $firstIdentifier, string ...$identifiers)
+    {
+        return new static(...array_merge([$firstIdentifier], $identifiers));
+    }
+
+    public static function fromIdentifiersString(string $identifiers)
+    {
+        return new static(...explode(self::IDENTIFIERS_SEPARATOR, $identifiers));
+    }
+
+    public function getIdentifiers() : array
+    {
+        return $this->identifiers;
+    }
+
+    public function isEmpty() : bool
+    {
+        return empty($this->identifiers);
+    }
+
+    public function __toString() : string
+    {
+        return implode(self::IDENTIFIERS_SEPARATOR, $this->identifiers);
+    }
+}

src/Extension/Build.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Version\Extension;
+
+use Version\Exception\InvalidIdentifierException;
+
+class Build extends BaseExtension
+{
+    protected function validate(string $identifier) : void
+    {
+        if (! preg_match('/^[0-9A-Za-z\-]+$/', $identifier)) {
+            throw InvalidIdentifierException::forExtensionIdentifier($this, $identifier);
+        }
+    }
+}

src/Extension/NoBuild.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Version\Extension;
+
+class NoBuild extends Build
+{
+    public function __construct()
+    {
+        parent::__construct(...[]);
+    }
+}

src/Extension/NoPreRelease.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Version\Extension;
+
+class NoPreRelease extends PreRelease
+{
+    public function __construct()
+    {
+        parent::__construct(...[]);
+    }
+}

src/Extension/PreRelease.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Version\Extension;
+
+use Version\Exception\InvalidIdentifierException;
+
+class PreRelease extends BaseExtension
+{
+    protected function validate(string $identifier) : void
+    {
+        if (! preg_match('/^[0-9A-Za-z\-]+$/', $identifier)) {
+            throw InvalidIdentifierException::forExtensionIdentifier($this, $identifier);
+        }
+    }
+
+    public function compareTo(PreRelease $preRelease) : int
+    {
+        $firstPreReleaseIdentifiers = array_values($this->getIdentifiers());
+        $secondPreReleaseIdentifiers = array_values($preRelease->getIdentifiers());
+
+        $pr1Count = count($firstPreReleaseIdentifiers);
+        $pr2Count = count($secondPreReleaseIdentifiers);
+
+        $limit = min($pr1Count, $pr2Count);
+
+        for ($i = 0; $i < $limit; $i++) {
+            if ($firstPreReleaseIdentifiers[$i] === $secondPreReleaseIdentifiers[$i]) {
+                continue;
+            }
+
+            return $this->compareIdentifiers($firstPreReleaseIdentifiers[$i], $secondPreReleaseIdentifiers[$i]);
+        }
+
+        return $pr1Count - $pr2Count;
+    }
+
+    private function compareIdentifiers($identifier1, $identifier2) : int
+    {
+        $pr1IsAlpha = ctype_alpha($identifier1);
+        $pr2IsAlpha = ctype_alpha($identifier2);
+
+        if ($pr1IsAlpha xor $pr2IsAlpha) {
+            return $pr1IsAlpha ? 1 : -1;
+        }
+
+        if (ctype_digit($identifier1) && ctype_digit($identifier2)) {
+            return (int) $identifier1 - (int) $identifier2;
+        }
+
+        return strcmp($identifier1, $identifier2);
+    }
+}