Change interfaces of tag_compound and value once again

2 files changed, 43 insertions, 17 deletions

diff --git a/include/tag_compound.h b/include/tag_compound.h
index 3750e8a557..8d627fca67 100644
--- a/include/tag_compound.h
+++ b/include/tag_compound.h
@@ -58,12 +58,33 @@ public:
     /**
      * @brief Accesses a tag by key
      *
-     * If the key exists, returns a value to the corresponding tag.
-     * Else, a new uninitalized entry is created under this key.
+     * Returns a value to the tag with the specified key, or throws an
+     * exception if it does not exist.
+     * @throw std::out_of_range if given key does not exist
+     * @todo Make it create a new entry rather than throwing an exception
      */
     value& operator[](const std::string& key);
 
     /**
+     * @brief Inserts or assigns a tag
+     *
+     * If the given key already exists, assigns the tag to it.
+     * Otherwise, it is inserted under the given key.
+     * @return true if the key did not exist
+     */
+    bool put(const std::string& key, std::unique_ptr<tag>&& t);
+
+    /**
+     * @brief Constructs and assigns or inserts a tag into the compound
+     *
+     * Constructs a new tag of type @c T with the given args and inserts
+     * or assigns it to the given key.
+     * @return true if the key did not exist
+     */
+    template<class T, class... Args>
+    bool emplace(const std::string& key, Args&&... args);
+
+    /**
      * @brief Erases a tag from the compound
      * @return true if a tag was erased
      */
@@ -94,6 +115,12 @@ private:
     bool equals(const tag& rhs) const override;
 };
 
+template<class T, class... Args>
+bool tag_compound::emplace(const std::string& key, Args&&... args)
+{
+    return put(key, new T(std::forward<Args>(args)...));
+}
+
 }
 
 #endif // TAG_COMPOUND_H_INCLUDED
diff --git a/include/value.h b/include/value.h
index d55acf3c80..21e945625a 100644
--- a/include/value.h
+++ b/include/value.h
@@ -34,15 +34,15 @@ class tag_list;
 /**
  * @brief Contains an NBT value of fixed type
  *
- * A wrapper class that can contain a tag of an arbitrary but fixed type.
- * Casting or assigning incompatible types will throw an exception.
- * It can also refer to an uninitialized value (e.g. when using tag_compound::operator[]
- * with a non-existant key).
+ * A wrapper class that contains a dynamically allocated tag of a fixed type.
+ * Casting or assigning incompatible types will throw a exceptions.
  */
 class value
 {
 public:
     explicit value() {}
+    explicit value(std::unique_ptr<tag>&& t);
+    explicit value(tag&& t);
 
     //Movable but not (implicitly) copyable
     value(const value&) = delete;
@@ -50,9 +50,10 @@ public:
     value& operator=(const value&) = delete;
     value& operator=(value&&) = default;
 
-    //value& operator=(std::unique_ptr<tag>&& ptr);
+    value& operator=(std::unique_ptr<tag>&& t);
+    value& operator=(tag&& t);
 
-    //Assignment
+    //Assignment of primitives and string
     /**
      * @brief Assigns the given value to the tag if the type matches
      * @throw std::bad_cast if the value is not convertible to the tag type
@@ -65,8 +66,6 @@ public:
     value& operator=(float val);
     value& operator=(double val);
     value& operator=(const std::string& str);
-    value& operator=(tag_compound&& comp);
-    value& operator=(tag_list&& list);
 
     //Conversion to tag
     operator tag&();
@@ -78,13 +77,13 @@ public:
      * @throw std::bad_cast if the tag type is not convertible to the desired
      * type via a widening conversion
      */
-    explicit operator int8_t() const;
-    explicit operator int16_t() const;
-    explicit operator int32_t() const;
-    explicit operator int64_t() const;
-    explicit operator float() const;
-    explicit operator double() const;
-    explicit operator const std::string&() const;
+    operator int8_t() const;
+    operator int16_t() const;
+    operator int32_t() const;
+    operator int64_t() const;
+    operator float() const;
+    operator double() const;
+    operator const std::string&() const;
 
     /**
      * @brief In case of a tag_compound, accesses a tag by key with bounds checking