Add exercise for a singly linked list

exercises/SinglyLinkedList/Complete/NodeComplete.php

@@ -0,0 +1,31 @@
+<?php
+declare(strict_types=1);
+
+namespace Exercises\SinglyLinkedList\Complete;
+
+final class NodeComplete {
+
+  private $data;
+
+  private $link = null;
+
+  public function __construct(string $data)
+  {
+    $this->data = $data;
+  }
+
+  public function setLink(?NodeComplete $link): void
+  {
+    $this->link = $link;
+  }
+
+  public function getLink(): ?NodeComplete
+  {
+    return $this->link;
+  }
+
+  public function getData(): string
+  {
+    return $this->data;
+  }
+}

exercises/SinglyLinkedList/Complete/SinglyLinkedListComplete.php

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+<?php
+declare(strict_types=1);
+
+namespace Exercises\SinglyLinkedList\Complete;
+
+use Exercises\SinglyLinkedList\Complete\NodeComplete;
+
+final class SinglyLinkedListComplete
+{
+    private $head = null;
+    private $last = null;
+
+    public function add(NodeComplete $node): void
+    {
+        if (null === $this->head) {
+            $this->head = $node;
+        }
+        if ($this->last instanceof NodeComplete) {
+            $this->last->setLink($node);
+        }
+
+        $this->last = $node;
+    }
+
+    public function reverse(): void
+    {
+        $current = $this->head;
+        $new = null;
+
+        while (null !== $current) {
+            $temp = $current->getLink();
+            $current->setLink($new);
+            $new = $current;
+            $current = $temp;
+        }
+        $this->head = $new;
+    }
+
+    public function print(): string
+    {
+        $currentNode = $this->head;
+        $output = '';
+
+        while (null !== $currentNode) {
+            $output .= $currentNode->getData();
+            $currentNode = $currentNode->getLink();
+        }
+        return $output;
+    }
+}

exercises/SinglyLinkedList/Node.php

@@ -0,0 +1,27 @@
+<?php
+declare(strict_types=1);
+
+namespace Exercises\SinglyLinkedList;
+
+/**
+ * Create a Node.
+ * The node can have a linked node and a data string.
+ *
+ * @property string $data
+ * @property Node|null $link
+ *
+ * @method void setLink(Node $link)
+ * @method Node|null getLink()
+ * @method string getData()
+
+ * @example $node = new Node('first');
+ * $linkedNode = new Node('second');
+ * $node->setLink($linkedNode);
+ *
+ * $node->getData() -> 'first'
+ * $node->getLink() -> $linkedNode
+*/
+
+final class Node
+{
+}

exercises/SinglyLinkedList/SinglyLinkedList.php

@@ -0,0 +1,31 @@
+<?php
+declare(strict_types=1);
+
+namespace Exercises\SinglyLinkedList;
+
+/**
+ * Implement a singly linked-list
+ * Each element only knows about the next Node, but not the previous.
+ * Implement a print method, that prints all Node's data in their order.
+ * Implement a reverse method that reverses the order of the linked list.
+ *
+ * @property Node|null $head
+ * @property Node|null $last
+ * @method void add(Node $link)
+ * @method void reverse()
+ * @method string print()
+
+ * @example $list = new SinglyLinkedList;
+ * $list->add(new Node('a'));
+ * $list->add(new Node('b'));
+ * $list->add(new Node('c'));
+ *
+ * $list::print() -> abc
+ *
+ * $list->reverse();
+ * $list->print() -> cba
+ *
+*/
+final class SinglyLinkedList
+{
+}

tests/SinglyLinkedList/Complete/SinglyLinkedListCompleteTest.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Tests\SinglyLinkedList;
+
+use Exercises\SinglyLinkedList\Complete\SinglyLinkedListComplete;
+use Exercises\SinglyLinkedList\Complete\NodeComplete;
+use PHPUnit\Framework\TestCase;
+
+final class SinglyLinkedListCompleteTest extends TestCase
+{
+    private $list;
+
+    protected function setUp(): void
+    {
+        $this->list = new SinglyLinkedListComplete();
+    }
+
+    public function testHasMethods(): void
+    {
+        self::markTestSkipped();
+        self::assertTrue(
+            method_exists(SinglyLinkedListComplete::class, 'add'),
+            'Class does not have method add'
+        );
+        self::assertTrue(
+            method_exists(SinglyLinkedListComplete::class, 'reverse'),
+            'Class does not have method reverse'
+        );
+        self::assertTrue(
+            method_exists(SinglyLinkedListComplete::class, 'print'),
+            'Class does not have method print'
+        );
+    }
+
+    public function testPrint(): void
+    {
+        $this->list->add(new NodeComplete("a"));
+        $this->list->add(new NodeComplete("b"));
+        $this->list->add(new NodeComplete("c"));
+
+        self::assertSame('abc', $this->list->print());
+    }
+
+    public function testReverse(): void
+    {
+        $this->list->add(new NodeComplete("a"));
+        $this->list->add(new NodeComplete("b"));
+        $this->list->add(new NodeComplete("c"));
+        $this->list->reverse();
+        self::assertSame('cba', $this->list->print());
+    }
+}

tests/SinglyLinkedList/SinglyLinkedListTest.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Tests\SinglyLinkedList;
+
+use Exercises\SinglyLinkedList\Node;
+use Exercises\SinglyLinkedList\SinglyLinkedList;
+use PHPUnit\Framework\TestCase;
+
+final class SinglyLinkedListTest extends TestCase
+{
+    private $list;
+
+    protected function setUp(): void
+    {
+        $this->list = new SinglyLinkedList();
+    }
+
+    public function testHasMethods(): void
+    {
+        self::markTestSkipped();
+        self::assertTrue(
+            method_exists(SinglyLinkedList::class, 'add'),
+            'Class does not have method add'
+        );
+        self::assertTrue(
+            method_exists(SinglyLinkedList::class, 'reverse'),
+            'Class does not have method reverse'
+        );
+        self::assertTrue(
+            method_exists(SinglyLinkedList::class, 'print'),
+            'Class does not have method print'
+        );
+    }
+
+    public function testPrint(): void
+    {
+        self::markTestSkipped();
+        $this->list->add(new Node("a"));
+        $this->list->add(new Node("b"));
+        $this->list->add(new Node("c"));
+        self::assertSame('abc', $this->list->print());
+    }
+
+    public function testReverse(): void
+    {
+        self::markTestSkipped();
+        $this->list = new SinglyLinkedList;
+        $this->list->add(new Node("a"));
+        $this->list->add(new Node("b"));
+        $this->list->add(new Node("c"));
+
+        $this->list->reverse();
+        self::assertSame('cba', $this->list->print());
+    }
+}