// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements. See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership. The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License. You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied. See the License for the

// specific language governing permissions and limitations

// under the License.

// This file is copied from

// https://github.com/ClickHouse/ClickHouse/blob/master/src/Common/formatIPv6.cpp

// and modified by Doris

#include "exec/common/format_ip.h"

#include <algorithm>

#include <array>

namespace doris {

/** Further we want to generate constexpr array of strings with sizes from sequence of unsigned ints [0..N)

* in order to use this arrey for fast conversion of unsigned integers to strings

*/

namespace detail {

template <unsigned... digits>

struct ToChars {

static const char value[];

static const size_t size;

};

template <unsigned... digits>

constexpr char ToChars<digits...>::value[] = {('0' + digits)..., 0};

template <unsigned... digits>

constexpr size_t ToChars<digits...>::size = sizeof...(digits);

template <unsigned rem, unsigned... digits>

struct Decompose : Decompose<rem / 10, rem % 10, digits...> {};

template <unsigned... digits>

struct Decompose<0, digits...> : ToChars<digits...> {};

template <>

struct Decompose<0> : ToChars<0> {};

template <unsigned num>

struct NumToString : Decompose<num> {};

template <class T, T... ints>

consteval std::array<std::pair<const char*, size_t>, sizeof...(ints)> str_make_array_impl(

std::integer_sequence<T, ints...>) {

return std::array<std::pair<const char*, size_t>, sizeof...(ints)> {

std::pair<const char*, size_t> {NumToString<ints>::value, NumToString<ints>::size}...};

}

} // namespace detail

/** str_make_array<N>() - generates static array of std::pair<const char *, size_t> for numbers [0..N), where:

* first - null-terminated string representing number

* second - size of the string as would returned by strlen()

*/

template <size_t N>

consteval std::array<std::pair<const char*, size_t>, N> str_make_array() {

return detail::str_make_array_impl(std::make_integer_sequence<int, N> {});

}

/// This will generate static array of pair<const char *, size_t> for [0..255] at compile time

extern constexpr std::array<std::pair<const char*, size_t>, 256> one_byte_to_string_lookup_table =

str_make_array<256>();

} // namespace doris