callback/integer.hpp

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// Copyright (C) 2020-2023 Jonathan Müller and lexy contributors
// SPDX-License-Identifier: BSL-1.0
 
#ifndef LEXY_CALLBACK_INTEGER_HPP_INCLUDED
#define LEXY_CALLBACK_INTEGER_HPP_INCLUDED
 
#include <lexy/callback/base.hpp>
#include <lexy/dsl/sign.hpp>
 
namespace lexy
{
template <typename T>
struct _int
{
    using return_type = T;
 
    // You don't actually produce an integer value.
    constexpr T operator()(lexy::plus_sign) const  = delete;
    constexpr T operator()(lexy::minus_sign) const = delete;
 
    template <typename Integer>
    constexpr T operator()(const Integer& value) const
    {
        return T(value);
    }
    template <typename Integer>
    constexpr T operator()(lexy::plus_sign, const Integer& value) const
    {
        return T(value);
    }
    template <typename Integer>
    constexpr T operator()(lexy::minus_sign, const Integer& value) const
    {
        return T(-value);
    }
};
 
// A callback that takes an optional sign and an integer and produces the signed integer.
template <typename T>
constexpr auto as_integer = _int<T>{};
} // namespace lexy
 
#endif // LEXY_CALLBACK_INTEGER_HPP_INCLUDED