CharSet.hpp

/* SPDX-License-Identifier: MIT */
/* Copyright (c) 2022 Max Bachmann */
 
#pragma once
#include <array>
#include <limits>
#include <stdint.h>
#include <stdio.h>
#include <type_traits>
#include <unordered_set>
 
namespace rapidfuzz {
namespace detail {
 
/*
 * taken from https://stackoverflow.com/a/17251989
 */
template <typename T, typename U>
bool CanTypeFitValue(const U value)
{
    const intmax_t botT = intmax_t(std::numeric_limits<T>::min());
    const intmax_t botU = intmax_t(std::numeric_limits<U>::min());
    const uintmax_t topT = uintmax_t(std::numeric_limits<T>::max());
    const uintmax_t topU = uintmax_t(std::numeric_limits<U>::max());
    return !((botT > botU && value < static_cast<U>(botT)) || (topT < topU && value > static_cast<U>(topT)));
}
 
template <typename CharT1, size_t size = sizeof(CharT1)>
struct CharSet;
 
template <typename CharT1>
struct CharSet<CharT1, 1> {
    using UCharT1 = typename std::make_unsigned<CharT1>::type;
 
    std::array<bool, std::numeric_limits<UCharT1>::max() + 1> m_val;
 
    CharSet() : m_val{}
    {}
 
    void insert(CharT1 ch)
    {
        m_val[UCharT1(ch)] = true;
    }
 
    template <typename CharT2>
    bool find(CharT2 ch) const
    {
        if (!CanTypeFitValue<CharT1>(ch)) return false;
 
        return m_val[UCharT1(ch)];
    }
};
 
template <typename CharT1, size_t size>
struct CharSet {
    std::unordered_set<CharT1> m_val;
 
    CharSet() : m_val{}
    {}
 
    void insert(CharT1 ch)
    {
        m_val.insert(ch);
    }
 
    template <typename CharT2>
    bool find(CharT2 ch) const
    {
        if (!CanTypeFitValue<CharT1>(ch)) return false;
 
        return m_val.find(CharT1(ch)) != m_val.end();
    }
};
 
} // namespace detail
} // namespace rapidfuzz