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//===-- Holds an expected or unexpected value -------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_SUPPORT_CPP_EXPECTED_H
#define LLVM_LIBC_SUPPORT_CPP_EXPECTED_H
namespace __llvm_libc::cpp {
// This is used to hold an unexpected value so that a different constructor is
// selected.
template <class T> class unexpected {
T value;
public:
constexpr explicit unexpected(T value) : value(value) {}
constexpr T error() { return value; }
};
template <class T, class E> class expected {
union {
T exp;
E unexp;
};
bool is_expected;
public:
constexpr expected(T exp) : exp(exp), is_expected(true) {}
constexpr expected(unexpected<E> unexp)
: unexp(unexp.error()), is_expected(false) {}
constexpr bool has_value() { return is_expected; }
constexpr T value() { return exp; }
constexpr E error() { return unexp; }
constexpr operator T() { return exp; }
constexpr operator bool() { return is_expected; }
constexpr T &operator*() { return exp; }
constexpr const T &operator*() const { return exp; }
constexpr T *operator->() { return &exp; }
constexpr const T *operator->() const { return &exp; }
};
} // namespace __llvm_libc::cpp
#endif // LLVM_LIBC_SUPPORT_CPP_EXPECTED_H
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