mpd/src/util/TemplateString.hxx
2018-06-03 12:13:47 +02:00

127 lines
3.8 KiB
C++

/*
* Copyright (C) 2015-2016 Max Kellermann <max.kellermann@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef TEMPLATE_STRING_HXX
#define TEMPLATE_STRING_HXX
#include <stddef.h>
namespace TemplateString {
/**
* Construct a null-terminated string from a list of chars.
*/
template<char... _value>
struct Construct {
static constexpr char value[] = {_value..., 0};
static constexpr size_t size = sizeof...(_value);
};
template<char... _value>
constexpr char Construct<_value...>::value[];
/**
* An empty string.
*/
struct Empty : Construct<> {};
/**
* A string consisting of a single character.
*/
template<char ch>
struct CharAsString : Construct<ch> {};
/**
* Invoke #F, pass all characters in #src from #i to #length
* as variadic arguments.
*/
template<template<char...> class F,
const char *src, size_t length, size_t i,
char... _value>
struct VariadicChars : VariadicChars<F, src, length - 1, i + 1, _value..., src[i]> {
static_assert(length > 0, "Wrong length");
};
template<template<char...> class F,
const char *src, size_t length,
char... _value>
struct VariadicChars<F, src, 0, length, _value...> : F<_value...> {};
/**
* Like #VariadicChars, but pass an additional argument to #F.
*/
template<template<typename Arg, char...> class F, typename Arg,
const char *src, size_t length, size_t i,
char... _value>
struct VariadicChars1 : VariadicChars1<F, Arg,
src, length - 1, i + 1, _value..., src[i]> {
static_assert(length > 0, "Wrong length");
};
template<template<typename Arg, char...> class F, typename Arg,
const char *src, size_t length,
char... _value>
struct VariadicChars1<F, Arg, src, 0, length, _value...> : F<Arg, _value...> {};
template<const char *src, size_t length, char... value>
struct _BuildString : VariadicChars<Construct, src, length, 0,
value...> {};
template<char ch, typename S>
struct InsertBefore : _BuildString<S::value, S::size, ch> {};
/**
* Concatenate several strings.
*/
template<typename... Args>
struct Concat;
template<typename First, typename Second, typename... Args>
struct _Concat : Concat<Concat<First, Second>, Args...> {};
template<typename... Args>
struct Concat : _Concat<Args...> {};
template<typename Second, char... _value>
struct _Concat2 : _BuildString<Second::value, Second::size,
_value...> {};
template<typename First, typename Second>
struct Concat<First, Second>
:VariadicChars1<_Concat2, Second,
First::value, First::size, 0> {};
template<typename First>
struct Concat<First> : First {};
template<>
struct Concat<> : Empty {};
};
#endif