Add asEnumOf and enumOf functions

Author: klimick

composer.json

@@ -45,6 +45,7 @@
             "src/Fp/Functions/Callable/Partial.php",
             "src/Fp/Functions/Callable/PartialLeft.php",
             "src/Fp/Functions/Callable/PartialRight.php",
+            "src/Fp/Functions/Cast/AsEnumOf.php",
             "src/Fp/Functions/Cast/AsArray.php",
             "src/Fp/Functions/Cast/AsBool.php",
             "src/Fp/Functions/Cast/AsFloat.php",

src/Fp/Functions/Cast/AsEnumOf.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace Fp\Cast;
+
+use Closure;
+use BackedEnum;
+use Fp\Functional\Option\Option;
+
+/**
+ * Cast string or int to BackedEnum instance.
+ *
+ * ```php
+ * >>> asEnumOf(1, IntEnum::class)
+ * => Some(IntEnum(1))
+ * >>> asEnumOf(42, IntEnum::class)
+ * => None
+ * ```
+ *
+ * @template TEnum of BackedEnum
+ *
+ * @param class-string<TEnum> $enum
+ * @return Option<TEnum>
+ */
+function asEnumOf(mixed $subject, string $enum): Option
+{
+    if (!is_string($subject) && !is_int($subject)) {
+        return Option::none();
+    }
+
+    return Option::try(fn() => $enum::from($subject));
+}
+
+/**
+ * Curried version of {@see asEnumOf}.
+ *
+ * ```php
+ * >>> asEnumOf(IntEnum::class)(1)
+ * => Some(IntEnum(1))
+ * >>> asEnumOf(IntEnum::class)(42)
+ * => None
+ * ```
+ *
+ * @template TEnum of BackedEnum
+ *
+ * @param class-string<TEnum> $enum
+ * @return Closure(mixed): Option<TEnum>
+ */
+function enumOf(string $enum): Closure
+{
+    return fn(mixed $subject) => asEnumOf($subject, $enum);
+}

tests/Mock/IntEnum.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace Tests\Mock;
+
+enum IntEnum: int
+{
+    case FST = 1;
+    case SND = 2;
+    case THR = 3;
+}

tests/Mock/StringEnum.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace Tests\Mock;
+
+enum StringEnum: string
+{
+    case FST = 'fst';
+    case SND = 'snd';
+    case THR = 'thr';
+}

tests/Runtime/Functions/Cast/CastTest.php

@@ -5,10 +5,14 @@
 namespace Tests\Runtime\Functions\Cast;
 
 use Fp\Functional\Option\None;
+use Fp\Functional\Option\Option;
 use PHPUnit\Framework\TestCase;
 use Tests\Mock\Baz;
 use Tests\Mock\Foo;
 
+use Tests\Mock\IntEnum;
+use Tests\Mock\StringEnum;
+use function Fp\Cast\asEnumOf;
 use function Fp\Cast\asGenerator;
 use function Fp\Cast\asArray;
 use function Fp\Cast\asBool;
@@ -20,6 +24,7 @@
 use function Fp\Cast\asPairs;
 use function Fp\Cast\asPairsGenerator;
 use function Fp\Cast\asString;
+use function Fp\Cast\enumOf;
 use function Fp\Cast\fromPairs;
 
 final class CastTest extends TestCase
@@ -31,6 +36,44 @@ public function testAsArray(): void
         $this->assertEquals($c, asArray($c));
     }
 
+    public function testAsEnumOf(): void
+    {
+        $this->assertEquals(Option::none(), asEnumOf(0, IntEnum::class));
+        $this->assertEquals(Option::none(), asEnumOf('fst', IntEnum::class));
+        $this->assertEquals(Option::none(), asEnumOf(0.42, IntEnum::class));
+        $this->assertEquals(Option::none(), asEnumOf([], IntEnum::class));
+        $this->assertEquals(Option::some(IntEnum::FST), asEnumOf(1, IntEnum::class));
+        $this->assertEquals(Option::some(IntEnum::SND), asEnumOf(2, IntEnum::class));
+        $this->assertEquals(Option::some(IntEnum::THR), asEnumOf(3, IntEnum::class));
+
+        $this->assertEquals(Option::none(), asEnumOf(0, StringEnum::class));
+        $this->assertEquals(Option::none(), asEnumOf(0.42, StringEnum::class));
+        $this->assertEquals(Option::none(), asEnumOf([], StringEnum::class));
+        $this->assertEquals(Option::none(), asEnumOf('fth', StringEnum::class));
+        $this->assertEquals(Option::some(StringEnum::FST), asEnumOf('fst', StringEnum::class));
+        $this->assertEquals(Option::some(StringEnum::SND), asEnumOf('snd', StringEnum::class));
+        $this->assertEquals(Option::some(StringEnum::THR), asEnumOf('thr', StringEnum::class));
+    }
+
+    public function testEnumOf(): void
+    {
+        $this->assertEquals(Option::none(), enumOf(IntEnum::class)(0));
+        $this->assertEquals(Option::none(), enumOf(IntEnum::class)('fst'));
+        $this->assertEquals(Option::none(), enumOf(IntEnum::class)(0.42));
+        $this->assertEquals(Option::none(), enumOf(IntEnum::class)([]));
+        $this->assertEquals(Option::some(IntEnum::FST), enumOf(IntEnum::class)(1));
+        $this->assertEquals(Option::some(IntEnum::SND), enumOf(IntEnum::class)(2));
+        $this->assertEquals(Option::some(IntEnum::THR), enumOf(IntEnum::class)(3));
+
+        $this->assertEquals(Option::none(), enumOf(StringEnum::class)(0));
+        $this->assertEquals(Option::none(), enumOf(StringEnum::class)(0.42));
+        $this->assertEquals(Option::none(), enumOf(StringEnum::class)([]));
+        $this->assertEquals(Option::none(), enumOf(StringEnum::class)('fth'));
+        $this->assertEquals(Option::some(StringEnum::FST), enumOf(StringEnum::class)('fst'));
+        $this->assertEquals(Option::some(StringEnum::SND), enumOf(StringEnum::class)('snd'));
+        $this->assertEquals(Option::some(StringEnum::THR), enumOf(StringEnum::class)('thr'));
+    }
+
     public function testAsBool(): void
     {
         $this->assertTrue(asBool('true')->get());