141 lines
5.0 KiB
C++
141 lines
5.0 KiB
C++
/* -*- C++ -*-
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* Serene Programming Language
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*
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* Copyright (c) 2019-2022 Sameer Rahmani <lxsameer@gnu.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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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 "serene/export.h"
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#include <llvm/Support/Error.h>
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#include <variant>
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// Sometimes we need this to make both analyzer happy
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// and the fn signature right.
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#define UNUSED(x) (void)(x)
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// We use this value with llvm::SmallString<MAX_PATH_SLOTS>
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#define MAX_PATH_SLOTS 256
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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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///
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/// This class is setup in a way tha you can us a value of type `T` in places
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/// that the compiler expects a `Result<T>`. So for example:
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///
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/// \code
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/// Result<int> fn() {return 2;}
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/// \endcode
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///
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/// works perfectly.
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template <typename T, typename E = llvm::Error>
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class SERENE_EXPORT 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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constexpr Result(const T &v)
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: Result(std::in_place_index_t<0>(), std::move(v)){};
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/// Return a pointer to the success case value of the result. It is
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/// important to check for the success case before calling this function.
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constexpr const T *getPointer() const { return &getValue(); }
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/// Return a pointer to the success case value of the result. It is
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/// important to check for the success case before calling this function.
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T *getPointer() { return &getValue(); }
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/// Return a pointer to the success case value of the result. It is
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/// important to check for the success case before calling this function.
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T *operator->() { return getPointer(); }
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/// Return a pointer to the success case value of the result. It is
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/// important to check for the success case before calling this function.
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constexpr const T *operator->() const { return getPointer(); }
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/// Dereference the success case and returns the value. It is
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/// important to check for the success case before calling this function.
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constexpr const T &operator*() const & { return getValue(); }
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/// Dereference the success case and returns the value. It is
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/// important to check for the success case before calling this function.
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T &operator*() & { return getValue(); }
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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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/// Return the value if it's successful otherwise throw an error
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T &&getValue() && { return std::move(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::move(std::get<1>(contents)); };
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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<T>(contents); };
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operator bool() const { return ok(); }
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};
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inline void makeFQSymbolName(const llvm::StringRef &ns,
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const llvm::StringRef &sym, std::string &result) {
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result = (ns + "/" + sym).str();
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};
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} // namespace serene
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#endif
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