/*
 * charybdis: 21st Century IRC++d
 * util.h: Miscellaneous utilities
 *
 * Copyright (C) 2016 Charybdis Development Team
 * Copyright (C) 2016 Jason Volk <jason@zemos.net>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice is present in all copies.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#pragma once
#define HAVE_IRCD_BYTE_VIEW_H

namespace ircd
{
	template<class T = string_view> struct byte_view;
	template<> struct byte_view<string_view>;
}

/// string_view -> bytes
template<class T>
struct ircd::byte_view
{
	string_view s;

	operator const T &() const
	{
		if(unlikely(sizeof(T) > s.size()))
			throw std::bad_cast();

		return *reinterpret_cast<const T *>(s.data());
	}

	byte_view(const string_view &s = {})
	:s{s}
	{
		if(unlikely(sizeof(T) > s.size()))
			throw std::bad_cast();
	}

	// bytes -> bytes (completeness)
	byte_view(const T &t)
	:s{byte_view<string_view>{t}}
	{}
};

/// bytes -> string_view. A byte_view<string_view> is raw data of byte_view<T>.
///
/// This is an important specialization to take note of. When you see
/// byte_view<string_view> know that another type's bytes are being represented
/// by the string_view if that type is not string_view family itself.
template<>
struct ircd::byte_view<ircd::string_view>
:string_view
{
	template<class T,
	         typename std::enable_if<!std::is_base_of<std::string_view, T>::value, int *>::type = nullptr>
	byte_view(const T &t)
	:string_view{reinterpret_cast<const char *>(&t), sizeof(T)}
	{}

	/// string_view -> string_view (completeness)
	byte_view(const string_view &t)
	:string_view{t}
	{}
};