feat: implemented Byter

README.md

@@ -1,7 +1,7 @@
 # Library for work with binary data and objects
 
 Simple library for work with binary data and objects in PHP.
-See the examples below for more information, or check out [`Encoder`](./src/Encoder.php), [`Decoder`](./src/Decoder.php) and [`Serializer`](./src/Serializer.php).
+See the examples below for more information, or check out [`Encoder`](./src/Encoder.php), [`Decoder`](./src/Decoder.php), [`Serializer`](./src/Serializer.php) and [`Byter`](./src/Byter.php).
 
 ```php
 use PetrKnap\Binary\Binary;
@@ -26,6 +26,22 @@ $unserialized = Binary::unserialize($serialized);
 printf('Data was serialized into `%s` %s.', base64_encode($serialized), $unserialized === $data ? 'successfully' : 'unsuccessfully');
 ```
 
+```php
+use PetrKnap\Binary\Binary;
+
+$data = base64_decode('hmlpFnFwbchsoQARSibVpfbWVfuwAHLbGxjFl9eC8fiGaWkWcXBtyGyhABFKJtWl9tZV+7AActsbGMWX14Lx+A==');
+$sha1 = sha1($data, binary: true);
+$md5 = md5($data, binary: true);
+$unbitten = Binary::unbite($sha1, $md5, $data);
+[$sha1Bite, $md5Bite, $dataBite] = Binary::bite($unbitten, 20, 16);
+
+printf(
+    'Hashes and data was unbitten into `%s` %s.',
+    base64_encode($unbitten),
+    $sha1Bite === $sha1 && $md5Bite === $md5 && $dataBite === $data ? 'successfully' : 'unsuccessfully',
+);
+```
+
 ---
 
 Run `composer require petrknap/binary` to install it.

composer.json

@@ -65,7 +65,7 @@
   },
   "suggest": {
     "ext-igbinary": "Required to serialize data via igbinary",
-    "ext-mbstring": "Required to check checksum",
+    "ext-mbstring": "Required to bite bytes",
     "ext-zlib": "Required to compress data"
   }
 }

src/Binary.php

@@ -25,4 +25,22 @@ public static function unserialize(string $data): mixed
     {
         return (new Serializer())->unserialize(serialized: $data);
     }
+
+    /**
+     * @see Byter::bite()
+     *
+     * @return array<string>
+     */
+    public static function bite(string $data, int $size1, int ...$sizeN): array
+    {
+        return (new Byter())->bite($data, $size1, ...$sizeN);
+    }
+
+    /**
+     * @see Byter::unbite()
+     */
+    public static function unbite(string $bite1, string ...$biteN): string
+    {
+        return (new Byter())->unbite($bite1, ...$biteN);
+    }
 }

src/Byter.php

@@ -0,0 +1,75 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PetrKnap\Binary;
+
+use PetrKnap\Shorts\HasRequirements;
+use RuntimeException;
+
+class Byter
+{
+    use HasRequirements;
+
+    private const ENCODING = '8bit';
+
+    public function __construct()
+    {
+        self::checkRequirements(
+            functions: [
+                'mb_strcut',
+                'mb_strlen',
+            ],
+        );
+    }
+
+    /**
+     * @param int $size1 size of bite in bytes; if negative, bites from the end
+     *
+     * @return array<string> bites of specified sizes; and remains, if any
+     *
+     * @throws Exception\CouldNotBiteData
+     */
+    public function bite(string $data, int $size1, int ...$sizeN): array
+    {
+        $remains = $data;
+        $bites = [];
+        foreach ([$size1, ...$sizeN] as $size) {
+            if (abs($size) > $this->size($remains)) {
+                throw new Exception\CouldNotBiteData(__METHOD__, $data, new RuntimeException(
+                    'Remains are smaller than bite',
+                ));
+            }
+            $bite = mb_strcut($remains, 0, $size, encoding: self::ENCODING);
+            $remains = mb_strcut($remains, $size, encoding: self::ENCODING);
+            if ($size < 0) {
+                $bites[] = $remains;
+                $remains = $bite;
+            } else {
+                $bites[] = $bite;
+            }
+        }
+        if ($remains !== '') {
+            $bites[] = $remains;
+        }
+        return $bites;
+    }
+
+    /**
+     * Backward version of {@see self::bite()}
+     *
+     * @link https://en.wikipedia.org/wiki/Backwards_(Red_Dwarf)
+     */
+    public function unbite(string $bite1, string ...$biteN): string
+    {
+        return implode([$bite1, ...$biteN]);
+    }
+
+    /**
+     * @return int size in bytes
+     */
+    public function size(string $data): int
+    {
+        return mb_strlen($data, encoding: self::ENCODING);
+    }
+}

src/Coder/Checksum.php

@@ -4,7 +4,7 @@
 
 namespace PetrKnap\Binary\Coder;
 
-use PetrKnap\Shorts\HasRequirements;
+use PetrKnap\Binary\Byter;
 
 /**
  * @see hash()
@@ -13,20 +13,14 @@
  */
 final class Checksum extends Coder
 {
-    use HasRequirements;
-
     public const ALGORITHM = 'crc32';
 
     private string $algorithm;
+    private readonly Byter $byter;
 
     public function __construct()
     {
-        self::checkRequirements(
-            functions: [
-                'mb_strlen',
-                'mb_strcut',
-            ],
-        );
+        $this->byter = new Byter();
     }
 
     public function encode(string $decoded, ?string $algorithm = null): string
@@ -44,14 +38,13 @@ public function decode(string $encoded, ?string $algorithm = null): string
     protected function doEncode(string $decoded): string
     {
         $checksum = hash($this->algorithm, $decoded, binary: true);
-        return $decoded . $checksum;
+        return $this->byter->unbite($decoded, $checksum);
     }
 
     protected function doDecode(string $encoded): string
     {
-        $checksumLength = mb_strlen(hash($this->algorithm, '', binary: true), encoding: '8bit');
-        $dataLength = mb_strlen($encoded, encoding: '8bit') - $checksumLength;
-        $decoded = mb_strcut($encoded, 0, $dataLength, encoding: '8bit');
+        $checksumLength = $this->byter->size(hash($this->algorithm, '', binary: true));
+        [,$decoded] = $this->byter->bite($encoded, -$checksumLength);
         if ($this->doEncode($decoded) !== $encoded) {
             throw new Exception\CouldNotDecodeData(__METHOD__, $encoded);
         }

src/Exception/ByterException.php

@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PetrKnap\Binary\Exception;
+
+interface ByterException extends BinaryException
+{
+}

src/Exception/CouldNotBiteData.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PetrKnap\Binary\Exception;
+
+use PetrKnap\Shorts\Exception\CouldNotProcessData;
+
+/**
+ * @extends CouldNotProcessData<string>
+ */
+final class CouldNotBiteData extends CouldNotProcessData implements ByterException
+{
+}

tests/ByterTest.php

@@ -0,0 +1,62 @@
+<?php declare(strict_types=1);
+
+namespace PetrKnap\Binary;
+
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+final class ByterTest extends TestCase
+{
+    #[DataProvider('dataBitesData')]
+    public function testBitesData(array $expected, array $sizes): void
+    {
+        self::assertSame(
+            $expected,
+            (new Byter())->bite(self::getData(), ...$sizes),
+        );
+    }
+
+    public static function dataBitesData(): array
+    {
+        return [
+            'one left bite' => [[hex2bin('0102'), hex2bin('030405')], [2]],
+            'one right bite' => [[hex2bin('0405'), hex2bin('010203')], [-2]],
+            'empty bite' => [['', hex2bin('0102030405')], [0]],
+            'full bite' => [[hex2bin('0102030405')], [5]],
+            'many bites' => [[hex2bin('0102'), hex2bin('0405'), '', hex2bin('03')], [2, -2, 0, 1]],
+        ];
+    }
+
+    public function testBiteThrowsWhenThereIsNotEnoughData(): void
+    {
+        self::expectException(Exception\CouldNotBiteData::class);
+
+        $data = self::getData();
+        $byter = new Byter();
+        $byter->bite(
+            $data,
+            $byter->size($data) + 1,
+        );
+    }
+
+    public function testUnbitesBites(): void
+    {
+        self::assertSame(
+            self::getData(),
+            (new Byter())->unbite(hex2bin('0102'), hex2bin('030405')),
+        );
+    }
+
+    public function testReturnsSizeOfData(): void
+    {
+        self::assertSame(
+            5,
+            (new Byter())->size(self::getData()),
+        );
+    }
+
+    private static function getData(): string
+    {
+        return hex2bin('0102030405');
+    }
+}

tests/ReadmeTest.php

@@ -20,6 +20,7 @@ public static function getExpectedOutputsOfPhpExamples(): iterable
         return [
             'coder' => 'Data was coded into `a8vMFCssyD2Rs5BB0Evt6tJv10J_b2Aoui0tcXT69aaPP9oIyB-fLeAHAA` successfully.',
             'serializer' => 'Data was serialized into `S7QysqoutjKxUiqpLEhVsi62srRSysxNTE/VL8hLB/GBUimJJYkgpoWxlVJngJ87L5cUFwMDA6+nh0sQkGYEYQ42ICkveqQTxCkOcndiWHdO5iVYlYtjiER48o/9Ux7aM7C9Z1qixnnFBCjB4Onq57LOKaFJyboWAA==` successfully.',
+            'byter' => 'Hashes and data was unbitten into `IoPwxcGHZQM0gfF966vHI3kleehoRKHtC32Xh30RDlg5E026hmlpFnFwbchsoQARSibVpfbWVfuwAHLbGxjFl9eC8fiGaWkWcXBtyGyhABFKJtWl9tZV+7AActsbGMWX14Lx+A==` successfully.',
         ];
     }
 }