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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// -*- Mode: C++ -*-
//
// Copyright (C) 2019-2025 Google, Inc.
/// @file
#ifndef __ABG_CXX_COMPAT_H
#define __ABG_CXX_COMPAT_H
// C++17 support (via custom implementations if compiled with earlier standard)
#if __cplusplus >= 201703L
#include <optional>
#else
#include <stdexcept> // for throwing std::runtime_error("bad_optional_access")
#endif
namespace abg_compat {
#if __cplusplus >= 201703L
using std::optional;
#else
// <optional>
/// Simplified implementation of std::optional just enough to be used as a
/// replacement for our purposes and when compiling with pre C++17.
///
/// The implementation intentionally does not support a whole lot of features
/// to minimize the maintenance effort with this.
template <typename T> class optional
{
bool has_value_;
T value_;
public:
optional() : has_value_(false), value_() {}
optional(const T& value) : has_value_(true), value_(value) {}
bool
has_value() const noexcept
{
return has_value_;
}
const T&
value() const
{
if (!has_value_)
throw std::runtime_error("bad_optional_access");
return value_;
}
const T
value_or(const T& default_value) const
{
if (!has_value_)
return default_value;
return value_;
}
const T&
operator*() const& noexcept
{ return value_; }
T&
operator*() & noexcept
{ return value_; }
const T*
operator->() const noexcept
{ return &value_; }
T*
operator->() noexcept
{ return &value_; }
optional&
operator=(const T& value)
{
has_value_ = true;
value_ = value;
return *this;
}
explicit operator bool() const noexcept { return has_value(); }
};
template <typename T, typename U>
bool
operator==(const optional<T>& lhs, const optional<U>& rhs)
{
if (!lhs.has_value() && !rhs.has_value())
return true;
if (!lhs.has_value() || !rhs.has_value())
return false;
return lhs.value() == rhs.value();
}
template <typename T, typename U>
bool
operator!=(const optional<T>& lhs, const optional<U>& rhs)
{
return !(lhs == rhs);
}
#endif
}
#endif // __ABG_CXX_COMPAT_H
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