From 17b3adb61f2218901e1dce7d377fcadf822ae652 Mon Sep 17 00:00:00 2001
From: Oskar Stark <oskarstark@googlemail.com>
Date: Mon, 8 Sep 2025 10:49:24 +0200
Subject: [PATCH] Add constructor with configurable chunk size and overlap to
 TextSplitTransformer

- Add constructor to TextSplitTransformer with default values (chunkSize=1000, overlap=200)
- Add validation that overlap must be non-negative and less than chunk size
- Use constructor parameters as defaults when no options are provided in transform method
- Add comprehensive tests for constructor parameter validation
- Fix code style with PHP CS Fixer
---
 .../Transformer/TextSplitTransformer.php      | 13 ++++-
 .../Transformer/TextSplitTransformerTest.php  | 57 +++++++++++++++++++
 2 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/src/store/src/Document/Transformer/TextSplitTransformer.php b/src/store/src/Document/Transformer/TextSplitTransformer.php
index 772de9bf8..2f24b976a 100644
--- a/src/store/src/Document/Transformer/TextSplitTransformer.php
+++ b/src/store/src/Document/Transformer/TextSplitTransformer.php
@@ -29,13 +29,22 @@
     public const OPTION_CHUNK_SIZE = 'chunk_size';
     public const OPTION_OVERLAP = 'overlap';
 
+    public function __construct(
+        private int $chunkSize = 1000,
+        private int $overlap = 200,
+    ) {
+        if ($this->overlap < 0 || $this->overlap >= $this->chunkSize) {
+            throw new InvalidArgumentException(\sprintf('Overlap must be non-negative and less than chunk size. Got chunk size: %d, overlap: %d', $this->chunkSize, $this->overlap));
+        }
+    }
+
     /**
      * @param array{chunk_size?: int, overlap?: int} $options
      */
     public function transform(iterable $documents, array $options = []): iterable
     {
-        $chunkSize = $options[self::OPTION_CHUNK_SIZE] ?? 1000;
-        $overlap = $options[self::OPTION_OVERLAP] ?? 200;
+        $chunkSize = $options[self::OPTION_CHUNK_SIZE] ?? $this->chunkSize;
+        $overlap = $options[self::OPTION_OVERLAP] ?? $this->overlap;
 
         if ($overlap < 0 || $overlap >= $chunkSize) {
             throw new InvalidArgumentException('Overlap must be non-negative and less than chunk size.');
diff --git a/src/store/tests/Document/Transformer/TextSplitTransformerTest.php b/src/store/tests/Document/Transformer/TextSplitTransformerTest.php
index 98d092caa..a13cfb71d 100644
--- a/src/store/tests/Document/Transformer/TextSplitTransformerTest.php
+++ b/src/store/tests/Document/Transformer/TextSplitTransformerTest.php
@@ -184,6 +184,63 @@ public function testSplitWithNegativeOverlap()
         ]));
     }
 
+    public function testConstructorWithValidParameters()
+    {
+        $transformer = new TextSplitTransformer(500, 100);
+        $document = new TextDocument(Uuid::v4(), 'short text');
+
+        $chunks = iterator_to_array($transformer->transform([$document]));
+
+        $this->assertCount(1, $chunks);
+        $this->assertSame('short text', $chunks[0]->content);
+    }
+
+    public function testConstructorWithDefaultParameters()
+    {
+        $transformer = new TextSplitTransformer();
+        $document = new TextDocument(Uuid::v4(), 'short text');
+
+        $chunks = iterator_to_array($transformer->transform([$document]));
+
+        $this->assertCount(1, $chunks);
+        $this->assertSame('short text', $chunks[0]->content);
+    }
+
+    public function testConstructorWithNegativeOverlap()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Overlap must be non-negative and less than chunk size. Got chunk size: 1000, overlap: -1');
+
+        new TextSplitTransformer(1000, -1);
+    }
+
+    public function testConstructorWithOverlapEqualToChunkSize()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Overlap must be non-negative and less than chunk size. Got chunk size: 500, overlap: 500');
+
+        new TextSplitTransformer(500, 500);
+    }
+
+    public function testConstructorWithOverlapGreaterThanChunkSize()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Overlap must be non-negative and less than chunk size. Got chunk size: 100, overlap: 200');
+
+        new TextSplitTransformer(100, 200);
+    }
+
+    public function testConstructorParametersAreUsedAsDefaults()
+    {
+        $transformer = new TextSplitTransformer(150, 25);
+        $document = new TextDocument(Uuid::v4(), $this->getLongText());
+
+        $chunks = iterator_to_array($transformer->transform([$document]));
+
+        $this->assertCount(12, $chunks);
+        $this->assertSame(150, mb_strlen($chunks[0]->content));
+    }
+
     private function getLongText(): string
     {
         return trim(file_get_contents(\dirname(__DIR__, 5).'/fixtures/lorem.txt'));