From 75fbfea5a6b1b8ea63cbdae65a4e7654a3655152 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Filip=20=C5=81api=C5=84ski?=
 <143662975+f-lapinski@users.noreply.github.com>
Date: Thu, 6 Feb 2025 21:56:36 +0100
Subject: [PATCH] feat: create Folded Scalar function with Test (#1449)

* feat: create Folded Scalar function with Test

* Add Folded ScalarFunction

* Remove from DSL and fix to ScalarFunctionChain
---
 .../Flow/ETL/Function/ScalarFunctionChain.php |  5 +++
 .../etl/src/Flow/ETL/Function/StringFold.php  | 34 +++++++++++++++++++
 .../Tests/Unit/Function/StringFoldTest.php    | 22 ++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 src/core/etl/src/Flow/ETL/Function/StringFold.php
 create mode 100644 src/core/etl/tests/Flow/ETL/Tests/Unit/Function/StringFoldTest.php

diff --git a/src/core/etl/src/Flow/ETL/Function/ScalarFunctionChain.php b/src/core/etl/src/Flow/ETL/Function/ScalarFunctionChain.php
index f54f170ae..7bfa8831f 100644
--- a/src/core/etl/src/Flow/ETL/Function/ScalarFunctionChain.php
+++ b/src/core/etl/src/Flow/ETL/Function/ScalarFunctionChain.php
@@ -471,6 +471,11 @@ public function startsWith(ScalarFunction|string $needle) : self
         return new StartsWith($this, $needle);
     }
 
+    public function stringFold() : self
+    {
+        return new StringFold($this);
+    }
+
     public function strPad(int $length, string $pad_string = ' ', int $type = STR_PAD_RIGHT) : self
     {
         return new StrPad($this, $length, $pad_string, $type);
diff --git a/src/core/etl/src/Flow/ETL/Function/StringFold.php b/src/core/etl/src/Flow/ETL/Function/StringFold.php
new file mode 100644
index 000000000..6be7dcfc5
--- /dev/null
+++ b/src/core/etl/src/Flow/ETL/Function/StringFold.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flow\ETL\Function;
+
+use function Flow\ETL\DSL\type_string;
+use function Symfony\Component\String\u;
+use Flow\ETL\Function\ScalarFunction\TypedScalarFunction;
+use Flow\ETL\PHP\Type\Type;
+use Flow\ETL\Row;
+
+final class StringFold extends ScalarFunctionChain implements TypedScalarFunction
+{
+    public function __construct(private readonly ScalarFunction|string $string)
+    {
+    }
+
+    public function eval(Row $row) : mixed
+    {
+        $string = (new Parameter($this->string))->asString($row);
+
+        if ($string === null) {
+            return null;
+        }
+
+        return u($string)->folded()->toString();
+    }
+
+    public function returns() : Type
+    {
+        return type_string();
+    }
+}
diff --git a/src/core/etl/tests/Flow/ETL/Tests/Unit/Function/StringFoldTest.php b/src/core/etl/tests/Flow/ETL/Tests/Unit/Function/StringFoldTest.php
new file mode 100644
index 000000000..5721d611a
--- /dev/null
+++ b/src/core/etl/tests/Flow/ETL/Tests/Unit/Function/StringFoldTest.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flow\ETL\Tests\Unit\Function;
+
+use function Flow\ETL\DSL\row;
+use function Flow\ETL\DSL\{ref, str_entry};
+use Flow\ETL\Tests\FlowTestCase;
+
+final class StringFoldTest extends FlowTestCase
+{
+    public function test_string_folded() : void
+    {
+        self::assertSame(
+            "die o'brian strasse",
+            ref('str')->stringFold()->eval(
+                row(str_entry('str', "Die O'Brian Straße"))
+            )
+        );
+    }
+}