1 files changed, 74 insertions, 2 deletions

diff --git a/source/tanya/memory/package.d b/source/tanya/memory/package.d
index 3979fe0..9ecb45b 100644
--- a/source/tanya/memory/package.d
+++ b/source/tanya/memory/package.d
@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /**
- * Copyright: Eugene Wissner 2016.
+ * Copyright: Eugene Wissner 2016-2017.
  * 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)
@@ -14,7 +14,69 @@ import core.exception;
 public import std.experimental.allocator : make, makeArray;
 import std.traits;
 public import tanya.memory.allocator;
-public import tanya.memory.types;
+
+/**
+ * The mixin generates common methods for classes and structs using
+ * allocators. It provides a protected member, constructor and a read-only property,
+ * that checks if an allocator was already set and sets it to the default
+ * one, if not (useful for structs which don't have a default constructor).
+ */
+mixin template DefaultAllocator()
+{
+	/// Allocator.
+	protected shared Allocator allocator_;
+
+	/**
+	 * Params:
+	 * 	allocator = The allocator should be used.
+	 */
+	this(shared Allocator allocator)
+	in
+	{
+		assert(allocator !is null);
+	}
+	body
+	{
+		this.allocator_ = allocator;
+	}
+
+	/**
+	 * This property checks if the allocator was set in the constructor
+	 * and sets it to the default one, if not.
+	 *
+	 * Returns: Used allocator.
+	 *
+	 * Postcondition: $(D_INLINECODE allocator_ !is null)
+	 */
+	protected @property shared(Allocator) allocator() nothrow @safe @nogc
+	out (allocator)
+	{
+		assert(allocator !is null);
+	}
+	body
+	{
+		if (allocator_ is null)
+		{
+			allocator_ = defaultAllocator;
+		}
+		return allocator_;
+	}
+
+	/// Ditto.
+	@property shared(Allocator) allocator() const nothrow @trusted @nogc
+	out (allocator)
+	{
+		assert(allocator !is null);
+	}
+	body
+	{
+		if (allocator_ is null)
+		{
+			return defaultAllocator;
+		}
+		return cast(shared Allocator) allocator_;
+	}
+}
 
 // From druntime
 private extern (C) void _d_monitordelete(Object h, bool det) nothrow @nogc;
@@ -28,11 +90,21 @@ shared static this() nothrow @trusted @nogc
 }
 
 @property ref shared(Allocator) defaultAllocator() nothrow @safe @nogc
+out (allocator)
+{
+	assert(allocator !is null);
+}
+body
 {
 	return allocator;
 }
 
 @property void defaultAllocator(shared(Allocator) allocator) nothrow @safe @nogc
+in
+{
+	assert(allocator !is null);
+}
+body
 {
 	.allocator = allocator;
 }