Add true and false as PseudoTypes

In this change, I have made more allowance for identifying types as
PseudoTypes and to ensure they are identified as both their underlying
and pseudo-type.

Using instanceof, you can identify whether it is the PseudoType, a
pseudotype, but also as the underlying type.

Author: mvriel

src/PseudoType.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of phpDocumentor.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @link      http://phpdoc.org
+ */
+
+namespace phpDocumentor\Reflection;
+
+interface PseudoType extends Type
+{
+    public function underlyingType(): Type;
+}

src/PseudoTypes/False_.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace phpDocumentor\Reflection\PseudoTypes;
+
+use phpDocumentor\Reflection\PseudoType;
+use phpDocumentor\Reflection\Type;
+use phpDocumentor\Reflection\Types\Boolean;
+
+final class False_ extends Boolean implements PseudoType
+{
+    public function underlyingType(): Type
+    {
+        return new Boolean();
+    }
+
+    public function __toString(): string
+    {
+        return 'false';
+    }
+}

src/PseudoTypes/True_.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace phpDocumentor\Reflection\PseudoTypes;
+
+use phpDocumentor\Reflection\PseudoType;
+use phpDocumentor\Reflection\Type;
+use phpDocumentor\Reflection\Types\Boolean;
+
+final class True_ extends Boolean implements PseudoType
+{
+    public function underlyingType(): Type
+    {
+        return new Boolean();
+    }
+
+    public function __toString(): string
+    {
+        return 'true';
+    }
+}

src/TypeResolver.php

@@ -82,8 +82,8 @@ final class TypeResolver
         'scalar' => Types\Scalar::class,
         'callback' => Types\Callable_::class,
         'callable' => Types\Callable_::class,
-        'false' => Types\Boolean::class,
-        'true' => Types\Boolean::class,
+        'false' => PseudoTypes\False_::class,
+        'true' => PseudoTypes\False_::class,
         'self' => Types\Self_::class,
         '$this' => Types\This::class,
         'static' => Types\Static_::class,

src/Types/Boolean.php

@@ -18,7 +18,7 @@
 /**
  * Value Object representing a Boolean type.
  */
-final class Boolean implements Type
+class Boolean implements Type
 {
     /**
      * Returns a rendered output of the Type as it would be used in a DocBlock.

tests/unit/PseudoTypes/FalseTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of phpDocumentor.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @link      http://phpdoc.org
+ */
+
+namespace phpDocumentor\Reflection\PseudoTypes;
+
+use phpDocumentor\Reflection\Types\Boolean;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @coversDefaultClass \phpDocumentor\Reflection\Types\False_
+ */
+class FalseTest extends TestCase
+{
+    /**
+     * @covers ::underlyingType
+     */
+    public function testExposesUnderlyingType() : void
+    {
+        $false = new False_();
+
+        $this->assertInstanceOf(Boolean::class, $false->underlyingType());
+    }
+
+    /**
+     * @covers ::__toString
+     */
+    public function testFalseStringifyCorrectly() : void
+    {
+        $false = new False_();
+
+        $this->assertSame('false', (string) $false);
+    }
+}

tests/unit/PseudoTypes/TrueTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of phpDocumentor.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @link      http://phpdoc.org
+ */
+
+namespace phpDocumentor\Reflection\PseudoTypes;
+
+use phpDocumentor\Reflection\Types\Boolean;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @coversDefaultClass \phpDocumentor\Reflection\Types\True_
+ */
+class TrueTest extends TestCase
+{
+    /**
+     * @covers ::underlyingType
+     */
+    public function testExposesUnderlyingType() : void
+    {
+        $true = new True_();
+
+        $this->assertInstanceOf(Boolean::class, $true->underlyingType());
+    }
+
+    /**
+     * @covers ::__toString
+     */
+    public function testTrueStringifyCorrectly() : void
+    {
+        $true = new True_();
+
+        $this->assertSame('true', (string) $true);
+    }
+}