Paginator: add firstItemOnPage & lastItemOnPage [Closes #262] (#263)

Author: khorsky

src/Utils/Paginator.php

@@ -18,6 +18,8 @@
  * @property   int $page
  * @property-read int $firstPage
  * @property-read int|null $lastPage
+ * @property-read int $firstItemOnPage
+ * @property-read int $lastItemOnPage
  * @property   int $base
  * @property-read bool $first
  * @property-read bool $last
@@ -85,6 +87,26 @@ public function getLastPage(): ?int
 	}
 
 
+	/**
+	 * Returns the sequence number of the first element on the page
+	 */
+	public function getFirstItemOnPage(): int
+	{
+		return $this->itemCount !== 0
+			? $this->offset + 1
+			: 0;
+	}
+
+
+	/**
+	 * Returns the sequence number of the last element on the page
+	 */
+	public function getLastItemOnPage(): int
+	{
+		return $this->offset + $this->length;
+	}
+
+
 	/**
 	 * Sets first page (base) number.
 	 * @return static

tests/Utils/Paginator.phpt

@@ -24,6 +24,8 @@ test('', function () {
 	Assert::same(2, $paginator->pageCount);
 	Assert::same(0, $paginator->firstPage);
 	Assert::same(1, $paginator->lastPage);
+	Assert::same(7, $paginator->firstItemOnPage);
+	Assert::same(7, $paginator->lastItemOnPage);
 	Assert::same(6, $paginator->offset);
 	Assert::same(0, $paginator->countdownOffset);
 	Assert::same(1, $paginator->length);
@@ -38,6 +40,8 @@ test('', function () {
 	$paginator->page = -1;
 
 	Assert::same(0, $paginator->page);
+	Assert::same(1, $paginator->firstItemOnPage);
+	Assert::same(6, $paginator->lastItemOnPage);
 	Assert::same(0, $paginator->offset);
 	Assert::same(1, $paginator->countdownOffset);
 	Assert::same(6, $paginator->length);
@@ -55,6 +59,8 @@ test('', function () {
 	Assert::same(1, $paginator->pageCount);
 	Assert::same(0, $paginator->firstPage);
 	Assert::same(0, $paginator->lastPage);
+	Assert::same(1, $paginator->firstItemOnPage);
+	Assert::same(7, $paginator->lastItemOnPage);
 	Assert::same(0, $paginator->offset);
 	Assert::same(0, $paginator->countdownOffset);
 	Assert::same(7, $paginator->length);
@@ -72,6 +78,8 @@ test('', function () {
 	Assert::same(0, $paginator->pageCount);
 	Assert::same(0, $paginator->firstPage);
 	Assert::same(0, $paginator->lastPage);
+	Assert::same(0, $paginator->firstItemOnPage);
+	Assert::same(0, $paginator->lastItemOnPage);
 	Assert::same(0, $paginator->offset);
 	Assert::same(0, $paginator->countdownOffset);
 	Assert::same(0, $paginator->length);
@@ -89,6 +97,8 @@ test('', function () {
 	Assert::same(2, $paginator->pageCount);
 	Assert::same(1, $paginator->firstPage);
 	Assert::same(2, $paginator->lastPage);
+	Assert::same(7, $paginator->firstItemOnPage);
+	Assert::same(7, $paginator->lastItemOnPage);
 	Assert::same(6, $paginator->offset);
 	Assert::same(0, $paginator->countdownOffset);
 	Assert::same(1, $paginator->length);
@@ -102,23 +112,31 @@ test('', function () {
 	$paginator->setItemCount(0);
 	Assert::true($paginator->isFirst());
 	Assert::true($paginator->isLast());
+	Assert::same(0, $paginator->firstItemOnPage);
+	Assert::same(0, $paginator->lastItemOnPage);
 
 
 	// ItemCount: 1
 	$paginator->setItemCount(1);
 	Assert::true($paginator->isFirst());
 	Assert::true($paginator->isLast());
+	Assert::same(1, $paginator->firstItemOnPage);
+	Assert::same(1, $paginator->lastItemOnPage);
 
 
 	// ItemCount: 2
 	$paginator->setItemCount(2);
 	Assert::true($paginator->isFirst());
 	Assert::false($paginator->isLast());
+	Assert::same(1, $paginator->firstItemOnPage);
+	Assert::same(1, $paginator->lastItemOnPage);
 
 	// Page 2
 	$paginator->setPage(2);
 	Assert::false($paginator->isFirst());
 	Assert::true($paginator->isLast());
+	Assert::same(2, $paginator->firstItemOnPage);
+	Assert::same(2, $paginator->lastItemOnPage);
 });
 
 
@@ -132,6 +150,8 @@ test('', function () {
 	Assert::null($paginator->pageCount);
 	Assert::same(0, $paginator->firstPage);
 	Assert::null($paginator->lastPage);
+	Assert::same(19, $paginator->firstItemOnPage);
+	Assert::same(24, $paginator->lastItemOnPage);
 	Assert::same(18, $paginator->offset);
 	Assert::null($paginator->countdownOffset);
 	Assert::same(6, $paginator->length);