89 lines
3.4 KiB
C
89 lines
3.4 KiB
C
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/* -*- C++ -*-
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* Serene programming language.
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*
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* Copyright (c) 2019-2021 Sameer Rahmani <lxsameer@gnu.org>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef SERENE_UTILS_H
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#define SERENE_UTILS_H
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#include "llvm/Support/Error.h"
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#include <variant>
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// C++17 required. We can't go back to 14 any more :))
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namespace serene {
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/// A similar type to Rust's Result data structure. It either holds a value of
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/// type `T` successfully or holds a value of type `E` errorfully. It is
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/// designed to be used in situations which the return value of a function might
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/// contains some errors. The official way to use this type is to use the
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/// factory functions `Success` and `Error`. For example:
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///
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/// \code
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/// auto successfulResult = Result<int>::Success(3);
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/// auto notOkResult = Result<int>::Error(SomeLLVMError());
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// \endcode
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///
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/// In order check for a value being errorful or successful checkout the `ok`
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/// method or simply use the value as a conditiona.
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template <typename T, typename E = llvm::Error> class Result {
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// The actual data container
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std::variant<T, E> contents;
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/// The main constructor which we made private to avoid ambiguousness in
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/// input type. `Success` and `Error` call this ctor.
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template <typename InPlace, typename Content>
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Result(InPlace i, Content &&c) : contents(i, std::forward<Content>(c)){};
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public:
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/// Create a succesfull result with the given value of type `T`.
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static Result Success(T v) {
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return Result(std::in_place_index_t<0>(), std::move(v));
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}
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/// Create an errorful result with the given value of type `E` (default
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/// `llvm::Error`).
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static Result Error(E e) {
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return Result(std::in_place_index_t<1>(), std::move(e));
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}
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// using std::get, it'll throw if contents doesn't contain what you ask for
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/// Return the value if it's successful otherwise throw an error
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T &getValue() { return std::get<0>(contents); };
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/// Return the error value if it's errorful otherwise throw an error
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E &getError() { return std::get<1>(contents); };
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const T &getValue() const { return std::get<0>(contents); }
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const E &getError() const { return std::get<1>(contents); }
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/// Return the a boolean value indicating whether the value is succesful
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/// or errorful.
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bool ok() const { return std::holds_alternative<1>(contents); };
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operator bool() const { return ok(); }
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};
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} // namespace serene
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#endif
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