Implement CRTP for tag

4 files changed, 72 insertions, 39 deletions

diff --git a/include/crtp_tag.h b/include/crtp_tag.h
new file mode 100644
index 0000000000..f35b9d0c9a
--- /dev/null
+++ b/include/crtp_tag.h
@@ -0,0 +1,66 @@
+/*
+ * libnbt++ - A library for the Minecraft Named Binary Tag format.
+ * Copyright (C) 2013, 2015  ljfa-ag
+ *
+ * This file is part of libnbt++.
+ *
+ * libnbt++ is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * libnbt++ is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with libnbt++.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef CRTP_TAG_H_INCLUDED
+#define CRTP_TAG_H_INCLUDED
+
+#include "tag.h"
+
+namespace nbt
+{
+
+namespace detail
+{
+
+    template<class Sub>
+    class crtp_tag : public tag
+    {
+    public:
+        std::unique_ptr<tag> move_clone() && override final;
+
+    private:
+        bool equals(const tag& rhs) const override final;
+        tag& assign(tag&& rhs) override final;
+    };
+
+    template<class Sub>
+    std::unique_ptr<tag> crtp_tag<Sub>::move_clone() &&
+    {
+        return std::unique_ptr<tag>(
+            new Sub(static_cast<Sub&&>(*this))
+        );
+    }
+
+    template<class Sub>
+    bool crtp_tag<Sub>::equals(const tag& rhs) const
+    {
+        return *this == static_cast<const Sub&>(rhs);
+    }
+
+    template<class Sub>
+    tag& crtp_tag<Sub>::assign(tag&& rhs)
+    {
+        return *this = dynamic_cast<Sub&&>(rhs);
+    }
+
+}
+
+}
+
+#endif // CRTP_TAG_H_INCLUDED
diff --git a/include/tag_compound.h b/include/tag_compound.h
index 1b6e214b10..265479c8af 100644
--- a/include/tag_compound.h
+++ b/include/tag_compound.h
@@ -20,7 +20,7 @@
 #ifndef TAG_COMPOUND_H_INCLUDED
 #define TAG_COMPOUND_H_INCLUDED
 
-#include "tag.h"
+#include "crtp_tag.h"
 #include "value.h"
 #include <map>
 #include <string>
@@ -29,7 +29,7 @@ namespace nbt
 {
 
 ///Tag that contains multiple unordered named tags of arbitrary types
-class tag_compound final : public tag
+class tag_compound final : public detail::crtp_tag<tag_compound>
 {
 public:
     //Iterator types
@@ -108,17 +108,12 @@ public:
     const_iterator cend() const;
 
     tag_type get_type() const noexcept override;
-    std::unique_ptr<tag> move_clone() && override;
 
     friend bool operator==(const tag_compound& lhs, const tag_compound& rhs);
     friend bool operator!=(const tag_compound& lhs, const tag_compound& rhs);
 
 private:
     std::map<std::string, value> tags;
-
-    bool equals(const tag& rhs) const override;
-
-    tag_compound& assign(tag&& rhs) override;
 };
 
 template<class T, class... Args>
diff --git a/include/tag_primitive.h b/include/tag_primitive.h
index c58cb891ff..6087495048 100644
--- a/include/tag_primitive.h
+++ b/include/tag_primitive.h
@@ -20,7 +20,7 @@
 #ifndef TAG_PRIMITIVE_H_INCLUDED
 #define TAG_PRIMITIVE_H_INCLUDED
 
-#include "tag.h"
+#include "crtp_tag.h"
 #include "primitive_detail.h"
 #include <type_traits>
 
@@ -33,7 +33,7 @@ namespace nbt
  * Common class for tag_byte, tag_short, tag_int, tag_long, tag_float and tag_double.
  */
 template<class T>
-class tag_primitive final : public tag
+class tag_primitive final : public detail::crtp_tag<tag_primitive<T>>
 {
 public:
     ///The type of the value
@@ -52,14 +52,9 @@ public:
     void set(T value);
 
     tag_type get_type() const noexcept override;
-    std::unique_ptr<tag> move_clone() && override;
 
 private:
     T value;
-
-    bool equals(const tag& rhs) const override;
-
-    tag_primitive<T>& assign(tag&& rhs) override;
 };
 
 template<class T> bool operator==(const tag_primitive<T>& lhs, const tag_primitive<T>& rhs);
@@ -116,24 +111,6 @@ tag_type tag_primitive<T>::get_type() const noexcept
 }
 
 template<class T>
-std::unique_ptr<tag> tag_primitive<T>::move_clone() &&
-{
-    return std::unique_ptr<tag>(new tag_primitive<T>(std::move(*this)));
-}
-
-template<class T>
-bool tag_primitive<T>::equals(const tag& rhs) const
-{
-    return *this == static_cast<const tag_primitive<T>&>(rhs);
-}
-
-template<class T>
-tag_primitive<T>& tag_primitive<T>::assign(tag&& rhs)
-{
-    return *this = dynamic_cast<tag_primitive<T>&&>(rhs);
-}
-
-template<class T>
 bool operator==(const tag_primitive<T>& lhs, const tag_primitive<T>& rhs)
 {
     return lhs.get() == rhs.get();
diff --git a/include/tag_string.h b/include/tag_string.h
index b28476da2c..3c514bae96 100644
--- a/include/tag_string.h
+++ b/include/tag_string.h
@@ -20,14 +20,14 @@
 #ifndef TAG_STRING_H_INCLUDED
 #define TAG_STRING_H_INCLUDED
 
-#include "tag.h"
+#include "crtp_tag.h"
 #include <string>
 
 namespace nbt
 {
 
 ///Tag that contains a UTF-8 string
-class tag_string final : public tag
+class tag_string final : public detail::crtp_tag<tag_string>
 {
 public:
     ///The type of the tag
@@ -46,14 +46,9 @@ public:
     void set(std::string&& str);
 
     tag_type get_type() const noexcept override;
-    std::unique_ptr<tag> move_clone() && override;
 
 private:
     std::string value;
-
-    bool equals(const tag& rhs) const override;
-
-    tag_string& assign(tag&& rhs) override;
 };
 
 bool operator==(const tag_string& lhs, const tag_string& rhs);