Program Listing for File TypeList.hpp¶
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// Copyright 2018-2023 Xanadu Quantum Technologies Inc.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#pragma once
#include <cstdlib>
#include <tuple>
#include <type_traits>
#include <utility>
namespace Pennylane::Util {
template <typename T, typename... Ts> struct TypeNode {
using Type = T;
using Next = TypeNode<Ts...>;
};
template <typename T> struct TypeNode<T, void> {
using Type = T;
using Next = void;
};
template <typename T> struct TypeNode<T> {
using Type = T;
using Next = void;
};
template <typename... Ts> using TypeList = TypeNode<Ts...>;
template <typename TypeList, size_t n> struct getNth {
using Type = typename getNth<typename TypeList::Next, n - 1>::Type;
};
template <typename TypeList> struct getNth<TypeList, 0> {
static_assert(!std::is_same_v<typename TypeList::Type, void>,
"The given n is larger than the length of the type list.");
using Type = typename TypeList::Type;
};
template <typename TypeList, size_t n>
using getNthType = typename getNth<TypeList, n>::Type;
template <typename TypeList> constexpr size_t length() {
if constexpr (std::is_same_v<TypeList, void>) {
return 0;
} else {
return 1 + length<typename TypeList::Next>();
}
}
template <typename T, typename U> struct PrependToTypeList;
template <typename T, typename... Ts>
struct PrependToTypeList<T, TypeNode<Ts...>> {
using Type = TypeNode<T, Ts...>;
};
template <typename T> struct PrependToTypeList<T, void> {
using Type = TypeNode<T, void>;
};
} // namespace Pennylane::Util
api/program_listing_file_pennylane_lightning_core_src_utils_TypeList.hpp
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