Add DataReaderInterface::readOne()

src/Reader/DataReaderInterface.php

@@ -14,4 +14,5 @@ interface DataReaderInterface
      */
     public function withLimit(int $limit);
     public function read(): iterable;
+    public function readOne();
 }

src/Reader/Iterable/IterableDataReader.php

@@ -136,7 +136,7 @@ public function read(): iterable
 
             // skip offset items
             if ($skipped < $this->offset) {
-                $skipped++;
+                ++$skipped;
                 continue;
             }
 
@@ -149,6 +149,13 @@ public function read(): iterable
         return $data;
     }
 
+    public function readOne()
+    {
+        return (static function (iterable $data): \Generator {
+            yield from $data;
+        })($this->withLimit(1)->read())->current();
+    }
+
     public function withOffset(int $offset): self
     {
         $new = clone $this;

tests/Paginator/KeysetPaginatorTest.php

@@ -479,6 +479,11 @@ public function read(): iterable
                 return [];
             }
 
+            public function readOne()
+            {
+                return null;
+            }
+
             public function withFilter(FilterInterface $filter)
             {
                 // do nothing
@@ -504,6 +509,11 @@ public function read(): iterable
                 return [];
             }
 
+            public function readOne()
+            {
+                return null;
+            }
+
             public function withSort(?Sort $sorting)
             {
                 // do nothing

tests/Paginator/OffsetPaginatorTest.php

@@ -52,6 +52,10 @@ public function read(): iterable
             {
                 return [];
             }
+            public function readOne()
+            {
+                return null;
+            }
             public function count(): int
             {
                 return 0;
@@ -80,6 +84,10 @@ public function read(): iterable
             {
                 return [];
             }
+            public function readOne()
+            {
+                return null;
+            }
             public function count(): int
             {
                 return 0;

tests/Reader/IterableDataReaderTest.php

@@ -133,6 +133,26 @@ public function testCounting(): void
         $this->assertCount(5, $reader);
     }
 
+    public function testReadOne(): void
+    {
+        $data = $this->getDataSet();
+        $reader = new IterableDataReader($data);
+
+        $this->assertSame($data[0], $reader->readOne());
+    }
+
+    public function testReadOneWithSortingAndOffset(): void
+    {
+        $sorting = (new Sort(['id', 'name']))->withOrder(['name' => 'asc']);
+
+        $data = $this->getDataSet();
+        $reader = (new IterableDataReader($data))
+            ->withSort($sorting)
+            ->withOffset(2);
+
+        $this->assertSame($this->getDataSetSortedByName()[2], $reader->readOne());
+    }
+
     public function testsWithFilterIsImmutable(): void
     {
         $reader = new IterableDataReader([]);