vector/utility.hpp

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//---------------------------------------------------------------------------//
// Copyright (c) 2020-2021 Mikhail Komarov <nemo@nil.foundation>
// Copyright (c) 2020-2021 Nikita Kaskov <nbering@nil.foundation>
// Copyright (c) 2020-2021 Ilias Khairullin <ilias@nil.foundation>
//
// MIT License
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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//---------------------------------------------------------------------------//
 
#ifndef CRYPTO3_ALGEBRA_VECTOR_UTILITY_HPP
#define CRYPTO3_ALGEBRA_VECTOR_UTILITY_HPP
 
#include <nil/crypto3/algebra/vector/vector.hpp>
 
#include <tuple>
 
namespace nil {
    namespace crypto3 {
        namespace algebra {
 
            template<typename F, typename T, typename... Vectors,
                     typename U = std::invoke_result_t<F, T, typename Vectors::value_type...>,
                     std::size_t N = detail::all_same_value<std::size_t, Vectors::size...>::value>
            constexpr vector<U, N> elementwise(F f, const vector<T, N> &v, const Vectors &...vectors) {
                vector<U, N> op_applied = {};
                for (std::size_t i = 0; i < N; ++i)
                    op_applied[i] = std::apply(f, std::forward_as_tuple(v[i], vectors[i]...));
                return op_applied;
            }
 
            template<typename T, std::size_t N, typename F, typename U>
            constexpr U accumulate(const vector<T, N> &v, U init, F &&f) {
                U r = init;
                for (std::size_t i = 0; i < vector<T, N>::size; ++i)
                    r = std::apply(std::forward<F>(f), std::forward_as_tuple(r, v[i]));
                return r;
            }
 
            template<typename T, typename U, std::size_t N>
            constexpr vector<T, N> cast(const vector<U, N> &v) {
                return elementwise([](const U u) { return static_cast<T>(u); }, v);
            }
 
            template<std::size_t N, typename T>
            constexpr vector<T, N> iota(T value = T()) {
                vector<T, N> seq = {};
                for (auto &x : seq) {
                    x = value;
                    value += 1;    // equivalent to value++, see GCC Bug 91705
                }
                return seq;
            }
 
            template<std::size_t N, typename T>
            constexpr vector<T, N> linspace(T min, T max) {
                return ((max - min) / (N - 1)) * iota<N, T>() + min;
            }
 
            template<std::size_t N, typename T>
            constexpr vector<T, N> fill(T value) {
                vector<T, N> filled = {};
                for (auto &x : filled)
                    x = value;
                return filled;
            }
 
            template<std::size_t N, typename F>
            constexpr decltype(auto) generate(F &&f) {
                return elementwise(f, iota<N, std::size_t>());
            }
 
            template<std::size_t N, typename T>
            constexpr vector<T, N> rotate(vector<T, N> v, int n) {
                vector<T, N> rotated = {};
                // add N (the modulus) to n until it is positive
                while (n < 0)
                    n += N;
                for (std::size_t i = 0; i < N; ++i)
                    rotated[i] = v[(i + n) % N];
                return rotated;
            }
 
            template<std::size_t M, typename T, std::size_t N>
            constexpr vector<T, M> slice(vector<T, N> v, std::size_t start = 0) {
 
                vector<T, M> sliced = {};
                for (std::size_t i = 0; i < M; ++i)
                    sliced[i] = v[i + start];
 
                return sliced;
            }
 
            template<typename T, std::size_t N, std::size_t M>
            constexpr vector<T, N + M> concat(vector<T, N> a, vector<T, M> b) {
                vector<T, N + M> concatted = {};
                for (std::size_t i = 0; i < N; ++i)
                    concatted[i] = a[i];
                for (std::size_t i = 0; i < M; ++i)
                    concatted[i + N] = b[i];
                return concatted;
            }
 
        }    // namespace algebra
    }        // namespace crypto3
}    // namespace nil
#endif    // CRYPTO3_ALGEBRA_VECTOR_UTILITY_HPP