91 lines
2.4 KiB
C++
91 lines
2.4 KiB
C++
/*
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* Copyright 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <functional>
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#include <string_view>
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#include <ftl/details/type_traits.h>
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#include <ftl/string.h>
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namespace android::ftl::details {
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template <typename T, typename = void>
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struct StaticString;
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// Booleans.
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template <typename T>
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struct StaticString<T, std::enable_if_t<is_bool_v<T>>> {
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static constexpr std::size_t N = 5; // Length of "false".
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explicit constexpr StaticString(bool b) : view(b ? "true" : "false") {}
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const std::string_view view;
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};
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// Characters.
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template <typename T>
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struct StaticString<T, std::enable_if_t<is_char_v<T>>> {
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static constexpr std::size_t N = 1;
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explicit constexpr StaticString(char c) : character(c) {}
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const char character;
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const std::string_view view{&character, 1u};
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};
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// Integers, including the integer value of other character types like char32_t.
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template <typename T>
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struct StaticString<
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T, std::enable_if_t<std::is_integral_v<remove_cvref_t<T>> && !is_bool_v<T> && !is_char_v<T>>> {
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using U = remove_cvref_t<T>;
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static constexpr std::size_t N = to_chars_length_v<U>;
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// TODO: Mark this and to_chars as `constexpr` in C++23.
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explicit StaticString(U v) : view(to_chars(buffer, v)) {}
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to_chars_buffer_t<U> buffer;
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const std::string_view view;
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};
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// Character arrays.
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template <std::size_t M>
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struct StaticString<const char (&)[M], void> {
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static constexpr std::size_t N = M - 1;
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explicit constexpr StaticString(const char (&str)[M]) : view(str, N) {}
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const std::string_view view;
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};
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template <std::size_t N>
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struct Truncated {
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std::string_view view;
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};
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// Strings with constrained length.
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template <std::size_t M>
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struct StaticString<Truncated<M>, void> {
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static constexpr std::size_t N = M;
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explicit constexpr StaticString(Truncated<M> str) : view(str.view.substr(0, N)) {}
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const std::string_view view;
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};
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} // namespace android::ftl::details
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