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https://codeberg.org/wownero/wownero-lws
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95 lines
3.4 KiB
C++
95 lines
3.4 KiB
C++
// Copyright (c) 2020, The Monero Project
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#pragma once
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#include <type_traits>
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#include <utility>
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namespace wire
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{
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template<bool C>
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using enable_if = typename std::enable_if<C>::type;
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template<typename T>
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struct is_array : std::false_type
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{};
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template<typename T>
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struct is_blob : std::false_type
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{};
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/*! Forces field to be optional when empty. Concept requirements for `T` when
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`is_optional_on_empty<T>::value == true`:
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* must have an `empty()` method that toggles whether the associated
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`wire::field_<...>` is omitted by the `wire::writer`.
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* must have a `clear()` method where `empty() == true` upon completion,
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used by the `wire::reader` when the `wire::field_<...>` is omitted. */
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template<typename T>
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struct is_optional_on_empty
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: is_array<T> // all array types in old output engine were optional when empty
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{};
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// example usage : `wire::sum(std::size_t(wire::available(fields))...)`
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inline constexpr int sum() noexcept
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{
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return 0;
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}
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template<typename T, typename... U>
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inline constexpr T sum(const T head, const U... tail) noexcept
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{
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return head + sum(tail...);
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}
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//! If `T` has no `empty()` function, this function is used
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template<typename... T>
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inline constexpr bool empty(const T&...) noexcept
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{
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static_assert(sum(is_optional_on_empty<T>::value...) == 0, "type needs empty method");
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return false;
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}
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//! `T` has `empty()` function, use it
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template<typename T>
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inline auto empty(const T& container) -> decltype(container.empty())
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{ return container.empty(); }
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//! If `T` has no `clear()` function, this function is used
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template<typename... T>
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inline void clear(const T&...) noexcept
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{
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static_assert(sum(is_optional_on_empty<T>::value...) == 0, "type needs clear method");
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}
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//! `T` has `clear()` function, use it
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template<typename T>
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inline auto clear(T& container) -> decltype(container.clear())
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{ return container.clear(); }
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}
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