Add WriteOnceArray

Author: Sevavietl

README.md

@@ -17,6 +17,7 @@ Table of Contents
 * [XPath Key Array](#xpath-key-array)
 * [Dotted Key Array](#dotted-key-array)
 * [One-off Array](#one-off-array)
+* [Write-once Array](#write-once-array)
 
 <a name="composite-key-array"></a>
 
@@ -191,4 +192,27 @@ Compared to `CompositeKeyArray`, `DottedKeyArray` has some limitations:
 Sometimes you want to get value from an array by key and `unset` this key after that. The `OneOffArray` class helps you with this.
 
 Again this class can be used in combination with `CompositeKeyArray` or its descendents: `XPathKeyArray` or `DottedKeyArray`.
-Actually, it can be used in combination with any object that implemets `ArrayAccess`.
+Actually, it can be used in combination with any object that implemets `ArrayAccess`.
+
+<a name="write-once-array"></a>
+
+## Write-once Array
+
+If you want to be sure that each offset in your array would be written only once you can use `WriteOnceArray`. If you try to set one particular offset more than one time `IllegalOffsetException` will be thrown:
+
+```php
+$array = new WriteOnceArray();
+
+$array['foo'] = 'bar'; // => OK
+$array['foo'] = 'baz'; // => throws `IllegalOffsetException`
+```
+
+Because `offsetExists` method is used in order to ensure write-once behaviour, `offsetUnset` method call is illegal:
+
+```php
+$array = new WriteOnceArray([
+    'foo' => 'bar',
+]);
+
+unset($array['foo']); // => throws `IllegalOffsetUnsetMethodCallException`
+```

phpunit.xml.dist

@@ -7,8 +7,7 @@
          convertNoticesToExceptions="true"
          convertWarningsToExceptions="true"
          processIsolation="false"
-         stopOnFailure="false"
-         syntaxCheck="false">
+         stopOnFailure="false">
     <filter>
         <whitelist processUncoveredFilesFromWhitelist="true">
             <directory suffix=".php">./src</directory>

src/IllegalOffsetException.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace ThoroughPHP\Arrays;
+
+final class IllegalOffsetException extends \InvalidArgumentException
+{
+
+}

src/IllegalOffsetUnsetMethodCallException.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace ThoroughPHP\Arrays;
+
+final class IllegalOffsetUnsetMethodCallException extends \BadMethodCallException
+{
+
+}

src/WriteOnceArray.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace ThoroughPHP\Arrays;
+
+final class WriteOnceArray extends BaseArray
+{
+    public function offsetSet($offset, $value): void
+    {
+        if ($this->offsetExists($offset)) {
+            throw new IllegalOffsetException("Offset {$offset} was already written");
+        }
+
+        parent::offsetSet($offset, $value);
+    }
+
+    public function offsetUnset($offset): void
+    {
+        throw new IllegalOffsetUnsetMethodCallException("Cannot unset offset {$offset}. Array is write-once");
+    }
+}

tests/unit/WriteOnceArrayTest.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace ThoroughPHP\Arrays\Tests\Unit;
+
+use PHPUnit\Framework\TestCase;
+use ThoroughPHP\Arrays\IllegalOffsetException;
+use ThoroughPHP\Arrays\IllegalOffsetUnsetMethodCallException;
+use ThoroughPHP\Arrays\WriteOnceArray;
+
+final class WriteOnceArrayTest extends TestCase
+{
+    public function testOffsetSet(): void
+    {
+        $this->expectException(IllegalOffsetException::class);
+
+        $array = new WriteOnceArray();
+
+        $array['foo'] = 'bar';
+        $array['foo'] = 'baz';
+    }
+
+    public function testOffsetUnset(): void
+    {
+        $this->expectException(IllegalOffsetUnsetMethodCallException::class);
+
+        $array = new WriteOnceArray([
+            'foo' => 'bar',
+        ]);
+
+        unset($array['foo']);
+    }
+}