Add startsWith method

team-acaisia · Apr 26, 2023 · 9f8f62c · 9f8f62c
1 parent 1dc670c
commit 9f8f62c
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diff --git a/src/ByteArray.php b/src/ByteArray.php
@@ -44,6 +44,36 @@ public static function fromArray(array $array): self
         return $self;
     }
 
+    public function startsWith(int|string|ByteArray $startsWith): bool
+    {
+        // If its an int we just check the first one
+        if (is_int($startsWith)) {
+            if ($this->count() == 0) {
+                return false;
+            }
+            return $this->array[0] == $startsWith;
+        }
+
+        // If its a string, we cast to ByteArray
+        if (is_string($startsWith)) {
+            return $this->startsWith(self::fromString($startsWith));
+        }
+
+        $startsWithLength = $startsWith->count();
+        if ($startsWithLength == 0) {
+            return true; // Well, technically, each array starts with an empty array.. Maybe throw a warning?
+        }
+
+        if ($startsWithLength > $this->count()) {
+            // If the given is longer than our own, we bail out
+            return false;
+        }
+
+        // If not we cut out the same length array
+        $cut = array_slice($this->array, 0, $startsWithLength);
+        return $cut == $startsWith->toArray(); // and return if its the same or not
+    }
+
     public function append(ByteArray $array): self
     {
         foreach ($array->toArray() as $value) {

diff --git a/tests/ByteArrayTest.php b/tests/ByteArrayTest.php
@@ -157,4 +157,33 @@ public function testIterator(): void
         $this->assertSame(240, $array->current()); // First byte
     }
 
+    /**
+     * @dataProvider provideStartsWith
+     */
+    public function testStartsWith(ByteArray $given, $check, bool $expected): void
+    {
+        $this->assertSame($expected, $given->startsWith($check));
+    }
+
+    public static function provideStartsWith(): array
+    {
+        return [
+            [ByteArray::fromArray([]), ByteArray::fromArray([]), true],
+            [ByteArray::fromArray([]), '', true],
+            [ByteArray::fromArray([]), 0, false],
+            [ByteArray::fromArray([0]), 0, true],
+            [ByteArray::fromArray([0, 1, 2, 3]), 0, true],
+
+            [ByteArray::fromString('Testing?'), 'Testing?', true],
+            [ByteArray::fromString('Testing?'), 'Testing????', false],
+            [ByteArray::fromString('Testing?'), 'T', true],
+
+            [ByteArray::fromString('Testing?'), 0x54, true],
+            [ByteArray::fromString('Testing?'), 84, true],
+
+            [ByteArray::fromString('🚀🐸'), ByteArray::fromString('🚀🐸'), true],
+            [ByteArray::fromString('🚀🐸'), ByteArray::fromString('🚀'), true],
+            [ByteArray::fromString('🚀🐸'), '🚀', true],
+        ];
+    }
 }