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/*
* 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 TAG_H_INCLUDED
#define TAG_H_INCLUDED
#include <cstdint>
#include <iosfwd>
#include <memory>
#include "nbt_export.h"
namespace nbt
{
///Tag type values used in the binary format
enum class tag_type : int8_t
{
End = 0,
Byte = 1,
Short = 2,
Int = 3,
Long = 4,
Float = 5,
Double = 6,
Byte_Array = 7,
String = 8,
List = 9,
Compound = 10,
Int_Array = 11,
Long_Array = 12,
Null = -1 ///< Used to denote empty @ref value s
};
/**
* @brief Returns whether the given number falls within the range of valid tag types
* @param allow_end whether to consider tag_type::End (0) valid
*/
NBT_EXPORT bool is_valid_type(int type, bool allow_end = false);
//Forward declarations
class nbt_visitor;
class const_nbt_visitor;
namespace io
{
class stream_reader;
class stream_writer;
}
///Base class for all NBT tag classes
class NBT_EXPORT tag
{
public:
//Virtual destructor
virtual ~tag() noexcept {}
///Returns the type of the tag
virtual tag_type get_type() const noexcept = 0;
//Polymorphic clone methods
virtual std::unique_ptr<tag> clone() const& = 0;
virtual std::unique_ptr<tag> move_clone() && = 0;
std::unique_ptr<tag> clone() &&;
/**
* @brief Returns a reference to the tag as an instance of T
* @throw std::bad_cast if the tag is not of type T
*/
template<class T>
T& as();
template<class T>
const T& as() const;
/**
* @brief Move-assigns the given tag if the class is the same
* @throw std::bad_cast if @c rhs is not the same type as @c *this
*/
virtual tag& assign(tag&& rhs) = 0;
/**
* @brief Calls the appropriate overload of @c visit() on the visitor with
* @c *this as argument
*
* Implementing the Visitor pattern
*/
virtual void accept(nbt_visitor& visitor) = 0;
virtual void accept(const_nbt_visitor& visitor) const = 0;
/**
* @brief Reads the tag's payload from the stream
* @throw io::stream_reader::input_error on failure
*/
virtual void read_payload(io::stream_reader& reader) = 0;
/**
* @brief Writes the tag's payload into the stream
*/
virtual void write_payload(io::stream_writer& writer) const = 0;
/**
* @brief Default-constructs a new tag of the given type
* @throw std::invalid_argument if the type is not valid (e.g. End or Null)
*/
static std::unique_ptr<tag> create(tag_type type);
friend NBT_EXPORT bool operator==(const tag& lhs, const tag& rhs);
friend NBT_EXPORT bool operator!=(const tag& lhs, const tag& rhs);
private:
/**
* @brief Checks for equality to a tag of the same type
* @param rhs an instance of the same class as @c *this
*/
virtual bool equals(const tag& rhs) const = 0;
};
///Output operator for tag types
NBT_EXPORT std::ostream& operator<<(std::ostream& os, tag_type tt);
/**
* @brief Output operator for tags
*
* Uses @ref text::json_formatter
* @relates tag
*/
NBT_EXPORT std::ostream& operator<<(std::ostream& os, const tag& t);
template<class T>
T& tag::as()
{
static_assert(std::is_base_of<tag, T>::value, "T must be a subclass of tag");
return dynamic_cast<T&>(*this);
}
template<class T>
const T& tag::as() const
{
static_assert(std::is_base_of<tag, T>::value, "T must be a subclass of tag");
return dynamic_cast<const T&>(*this);
}
}
#endif // TAG_H_INCLUDED
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