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construct/include/ircd/json/iov.h
2017-11-30 11:23:40 -08:00

128 lines
3.7 KiB
C++

/*
* Copyright (C) 2017 Charybdis Development Team
* Copyright (C) 2017 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_JSON_IOV_H
namespace ircd::json
{
struct iov;
}
/// A forward list to compose JSON efficiently on the stack.
///
/// The IOV gathers members for a JSON object being assembled from various
/// sources and presents an iteration to a generator. This prevents the need
/// for multiple generations and copying to occur before the final JSON is
/// realized, if ever.
///
/// Add and remove items on the IOV by construction and destruction one of
/// the node objects. The IOV has a standard forward list interface, only use
/// that to observe and sort/rearrange the IOV. Do not add or remove things
/// that way.
///
/// Nodes support a single member each. To support initializer_list syntax
/// the iov allocates and internally manages the iov node that should have
/// been on your stack.
///
struct ircd::json::iov
:ircd::iov<ircd::json::member>
{
IRCD_EXCEPTION(json::error, error);
IRCD_EXCEPTION(error, exists);
struct push;
struct add;
struct add_if;
struct set;
struct set_if;
struct defaults;
struct defaults_if;
public:
bool has(const string_view &key) const;
const value &at(const string_view &key) const;
iov() = default;
friend string_view stringify(mutable_buffer &, const iov &);
friend std::ostream &operator<<(std::ostream &, const iov &);
friend size_t serialized(const iov &);
};
/// Unconditionally append a member to the object vector
struct ircd::json::iov::push
:protected ircd::json::iov::node
{
push(iov &iov, json::member m)
:node{iov, std::move(m)}
{}
push() = default;
};
/// Add a new member to the object vector; throws if exists
struct ircd::json::iov::add
:protected ircd::json::iov::node
{
add(iov &, member);
add() = default;
};
/// iov::add only if the bool argument is true for your condition
struct ircd::json::iov::add_if
:protected ircd::json::iov::node
{
add_if(iov &, const bool &, member);
add_if() = default;
};
/// Add or overwrite a member in the object vector.
struct ircd::json::iov::set
:protected ircd::json::iov::node
{
set(iov &, member);
set() = default;
};
/// iov::set only if the bool argument is true for your condition
struct ircd::json::iov::set_if
:protected ircd::json::iov::node
{
set_if(iov &, const bool &, member);
set_if() = default;
};
/// Add member to the object vector if doesn't exist; otherwise ignored
struct ircd::json::iov::defaults
:protected ircd::json::iov::node
{
defaults(iov &, member);
defaults() = default;
};
/// iov::defaults only if the bool argument is true for your condition
struct ircd::json::iov::defaults_if
:protected ircd::json::iov::node
{
defaults_if(iov &, const bool &, member);
defaults_if() = default;
};