From 7d5cd565593fc0d2802f842a31334dd3ad029ed3 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Sat, 27 Sep 2025 22:44:49 +0200
Subject: [PATCH 1/3] Add `concat()`, returns a concatenation of the sequence
 and the given enumerable

---
 src/main/php/util/data/Sequence.class.php        | 16 ++++++++++++++++
 .../data/unittest/SequenceCreationTest.class.php | 13 +++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/main/php/util/data/Sequence.class.php b/src/main/php/util/data/Sequence.class.php
index e507702..2f57e83 100755
--- a/src/main/php/util/data/Sequence.class.php
+++ b/src/main/php/util/data/Sequence.class.php
@@ -95,6 +95,22 @@ public static function generate($supplier) {
     return new self($f());
   }
 
+  /**
+   * Creates a new stream with an enumeration of elements
+   *
+   * @param  ?iterable|util.XPIterator|function(): iterable $enumerable
+   * @return self
+   * @throws lang.IllegalArgumentException if type of elements argument is incorrect
+   */
+  public function concat($enumerable) {
+    $enumeration= Enumeration::of($enumerable);
+    $f= function() use($enumeration) {
+      yield from $this->elements;
+      yield from $enumeration;
+    };
+    return new self($f());
+  }
+
   /**
    * Returns the first element of this stream, or an empty optional
    *
diff --git a/src/test/php/util/data/unittest/SequenceCreationTest.class.php b/src/test/php/util/data/unittest/SequenceCreationTest.class.php
index a1ff425..76deb69 100755
--- a/src/test/php/util/data/unittest/SequenceCreationTest.class.php
+++ b/src/test/php/util/data/unittest/SequenceCreationTest.class.php
@@ -73,4 +73,17 @@ public function passing_sequence_to_of_yields_itself() {
   public function multiple_arguments_supported_in_of(... $input) {
     $this->assertSequence([1, 2, 3, 4, 5, 6], Sequence::of(...$input));
   }
+
+  #[Test]
+  public function concat() {
+    $this->assertSequence(
+      [1, 2, 3, 4, 5, 6, 7, 8, 9],
+      Sequence::of([1, 2, 3])->concat([4, 5, 6])->concat([7, 8, 9])
+    );
+  }
+
+  #[Test, Expect(IllegalArgumentException::class)]
+  public function cannot_concat_non_enumerable() {
+    Sequence::$EMPTY->concat('test');
+  }
 }
\ No newline at end of file

From eb5a14b522ecdbafa7c1e7b7257b0aded92d8d8a Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Sat, 27 Sep 2025 22:47:51 +0200
Subject: [PATCH 2/3] Add test for concat() after map()

---
 .../php/util/data/unittest/SequenceCreationTest.class.php | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/test/php/util/data/unittest/SequenceCreationTest.class.php b/src/test/php/util/data/unittest/SequenceCreationTest.class.php
index 76deb69..50f3a4e 100755
--- a/src/test/php/util/data/unittest/SequenceCreationTest.class.php
+++ b/src/test/php/util/data/unittest/SequenceCreationTest.class.php
@@ -82,6 +82,14 @@ public function concat() {
     );
   }
 
+  #[Test]
+  public function concat_after_mapping() {
+    $this->assertSequence(
+      [2, 4, 6, 'EOF'],
+      Sequence::of([1, 2, 3])->map(fn($e) => $e * 2)->concat(['EOF'])
+    );
+  }
+
   #[Test, Expect(IllegalArgumentException::class)]
   public function cannot_concat_non_enumerable() {
     Sequence::$EMPTY->concat('test');

From 427b349b9631b86d840aba42603c389154959dd0 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Sat, 27 Sep 2025 22:48:54 +0200
Subject: [PATCH 3/3] Fix PHP < 7.4

---
 src/test/php/util/data/unittest/SequenceCreationTest.class.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/php/util/data/unittest/SequenceCreationTest.class.php b/src/test/php/util/data/unittest/SequenceCreationTest.class.php
index 50f3a4e..35df00d 100755
--- a/src/test/php/util/data/unittest/SequenceCreationTest.class.php
+++ b/src/test/php/util/data/unittest/SequenceCreationTest.class.php
@@ -86,7 +86,7 @@ public function concat() {
   public function concat_after_mapping() {
     $this->assertSequence(
       [2, 4, 6, 'EOF'],
-      Sequence::of([1, 2, 3])->map(fn($e) => $e * 2)->concat(['EOF'])
+      Sequence::of([1, 2, 3])->map(function($e) { return $e * 2; })->concat(['EOF'])
     );
   }