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source/tanya/container/queue.d

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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Copyright: Eugene Wissner 2016.
+ * License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
+ *                  Mozilla Public License, v. 2.0).
+ * Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
+ */  
+module tanya.container.queue;
+
+import tanya.memory;
+
+/**
+ * Queue.
+ *
+ * Params:
+ * 	T = Content type.
+ */
+class Queue(T)
+{
+@nogc:
+	/**
+	 * Creates a new $(D_PSYMBOL Queue).
+	 *
+	 * Params:
+	 * 	allocator = The allocator should be used for the element
+	 * 	            allocations.
+	 */
+	this(Allocator allocator = defaultAllocator)
+	{
+		this.allocator = allocator;
+	}
+
+	/**
+	 * Removes all elements from the queue.
+	 */
+	~this()
+	{
+		foreach (e; this)
+		{
+            static if (isFinalizable!T)
+            {
+                finalize(allocator, e);
+            }
+		}
+	}
+
+	/**
+	 * Returns: First element.
+	 */
+	@property ref T front()
+	in
+	{
+		assert(!empty);
+	}
+	body
+	{
+		return first.next.content;
+	}
+
+	/**
+	 * Inserts a new element.
+	 *
+	 * Params:
+	 * 	x = New element.
+	 *
+	 * Returns: $(D_KEYWORD this).
+	 */
+	typeof(this) insertBack(T x)
+	{
+		Entry* temp = make!Entry(allocator);
+		
+		temp.content = x;
+
+		if (empty)
+		{
+			first.next = rear = temp;
+		}
+		else
+		{
+			rear.next = temp;
+			rear = rear.next;
+		}
+
+		return this;
+	}
+
+	alias insert = insertBack;
+
+	///
+	unittest
+	{
+		auto q = make!(Queue!int)(defaultAllocator);
+		int[2] values = [8, 9];
+
+		q.insertBack(values[0]);
+		assert(q.front is values[0]);
+		q.insertBack(values[1]);
+		assert(q.front is values[0]);
+
+		finalize(defaultAllocator, q);
+	}
+
+	/**
+	 * Inserts a new element.
+	 *
+	 * Params:
+	 * 	x = New element.
+	 *
+	 * Returns: $(D_KEYWORD this).
+	 */
+	typeof(this) opOpAssign(string Op)(ref T x)
+		if (Op == "~")
+	{
+		return insertBack(x);
+	}
+
+	///
+	unittest
+	{
+		auto q = make!(Queue!int)(defaultAllocator);
+		int value = 5;
+
+		assert(q.empty);
+
+		q ~= value;
+
+		assert(q.front == value);
+		assert(!q.empty);
+
+		finalize(defaultAllocator, q);
+	}
+
+	/**
+	 * Returns: $(D_KEYWORD true) if the queue is empty.
+	 */
+	@property bool empty() const @safe pure nothrow
+	{
+		return first.next is null;
+	}
+
+	///
+	unittest
+	{
+		auto q = make!(Queue!int)(defaultAllocator);
+		int value = 7;
+
+		assert(q.empty);
+		q.insertBack(value);
+		assert(!q.empty);
+
+		finalize(defaultAllocator, q);
+	}
+
+	/**
+	 * Move position to the next element.
+	 *
+	 * Returns: $(D_KEYWORD this).
+	 */
+	typeof(this) popFront()
+	in
+	{
+		assert(!empty);
+	}
+	body
+	{
+		auto n = first.next.next;
+
+		finalize(allocator, first.next);
+		first.next = n;
+
+        return this;
+	}
+
+	///
+	unittest
+	{
+		auto q = make!(Queue!int)(defaultAllocator);
+		int[2] values = [8, 9];
+
+		q.insertBack(values[0]);
+		q.insertBack(values[1]);
+		assert(q.front is values[0]);
+		q.popFront();
+		assert(q.front is values[1]);
+
+		finalize(defaultAllocator, q);
+	}
+
+	/**
+	 * Queue entry.
+	 */
+	protected struct Entry
+	{
+		/// Queue item content.
+		T content;
+
+		/// Next list item.
+		Entry* next;
+	}
+
+	/// The first element of the list.
+	protected Entry first;
+
+	/// The last element of the list.
+	protected Entry* rear;
+
+	private Allocator allocator;
+}
+
+///
+unittest
+{
+	auto q = make!(Queue!int)(defaultAllocator);
+
+	finalize(defaultAllocator, q);
+}