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/*
* charybdis: 21st Century IRC++d
* util.h: Miscellaneous utilities
*
* Copyright (C) 2016 Charybdis Development Team
* Copyright (C) 2016 Jason Volk <jason@zemos.net>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice is present in all copies.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
*/
#pragma once
#define HAVE_IRCD_UTIL_H
namespace ircd {
inline namespace util {
#define IRCD_EXPCAT(a, b) a ## b
#define IRCD_CONCAT(a, b) IRCD_EXPCAT(a, b)
#define IRCD_UNIQUE(a) IRCD_CONCAT(a, __COUNTER__)
#define IRCD_OVERLOAD(NAME) \
static constexpr struct NAME##_t {} NAME {};
#define IRCD_USING_OVERLOAD(ALIAS, ORIGIN) \
static constexpr const auto &ALIAS{ORIGIN}
#define IRCD_WEAK_TYPEDEF(TYPE, NAME) \
struct NAME \
:TYPE \
{ \
using TYPE::TYPE; \
};
#define IRCD_STRONG_TYPEDEF(TYPE, NAME) \
struct NAME \
{ \
TYPE val; \
\
explicit operator const TYPE &() const { return val; } \
explicit operator TYPE &() { return val; } \
};
#define IRCD_WEAK_T(TYPE) \
IRCD_WEAK_TYPEDEF(TYPE, IRCD_UNIQUE(weak_t))
// ex: using foo_t = IRCD_STRONG_T(int)
#define IRCD_STRONG_T(TYPE) \
IRCD_STRONG_TYPEDEF(TYPE, IRCD_UNIQUE(strong_t))
// for complex static initialization (try to avoid this though)
enum class init_priority
{
FIRST = 101,
STD_CONTAINER = 102,
};
#define IRCD_INIT_PRIORITY(name) \
__attribute__((init_priority(int(ircd::init_priority::name))))
struct scope
{
struct nominal;
struct exceptional;
const std::function<void ()> func;
template<class F>
scope(F &&func): func(std::forward<F>(func)) {}
scope() = default;
scope(const scope &) = delete;
scope &operator=(const scope &) = delete;
~scope() noexcept
{
func();
}
};
struct scope::nominal
:scope
{
template<class F>
nominal(F &&func)
:scope
{
[func(std::forward<F>(func))]
{
if(likely(!std::uncaught_exception()))
func();
}
}{}
nominal() = default;
};
struct scope::exceptional
:scope
{
template<class F>
exceptional(F &&func)
:scope
{
[func(std::forward<F>(func))]
{
if(unlikely(std::uncaught_exception()))
func();
}
}{}
exceptional() = default;
};
template<class T>
using custom_ptr = std::unique_ptr<T, std::function<void (T *) noexcept>>;
//
// Iteration of a tuple
//
// for_each(tuple, [](auto&& elem) { ... });
template<size_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == std::tuple_size<std::tuple<args...>>::value, void>::type
for_each(std::tuple<args...> &t,
func&& f)
{}
template<size_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == std::tuple_size<std::tuple<args...>>::value, void>::type
for_each(const std::tuple<args...> &t,
func&& f)
{}
template<size_t i = 0,
class func,
class... args>
constexpr
typename std::enable_if<i < std::tuple_size<std::tuple<args...>>::value, void>::type
for_each(const std::tuple<args...> &t,
func&& f)
{
f(std::get<i>(t));
for_each<i+1>(t, std::forward<func>(f));
}
template<size_t i = 0,
class func,
class... args>
constexpr
typename std::enable_if<i < std::tuple_size<std::tuple<args...>>::value, void>::type
for_each(std::tuple<args...> &t,
func&& f)
{
f(std::get<i>(t));
for_each<i+1>(t, std::forward<func>(f));
}
//
// Circuits for reverse iteration of a tuple
//
// rfor_each(tuple, [](auto&& elem) { ... });
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == 0, void>::type
rfor_each(const std::tuple<args...> &t,
func&& f)
{}
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == 0, void>::type
rfor_each(std::tuple<args...> &t,
func&& f)
{}
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<(i > 0), void>::type
rfor_each(const std::tuple<args...> &t,
func&& f)
{
f(std::get<i - 1>(t));
rfor_each<i - 1>(t, std::forward<func>(f));
}
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<(i > 0), void>::type
rfor_each(std::tuple<args...> &t,
func&& f)
{
f(std::get<i - 1>(t));
rfor_each<i - 1>(t, std::forward<func>(f));
}
template<ssize_t i = -1,
class func,
class... args>
constexpr
typename std::enable_if<(i == -1), void>::type
rfor_each(const std::tuple<args...> &t,
func&& f)
{
constexpr const ssize_t size
{
std::tuple_size<std::tuple<args...>>::value
};
rfor_each<size>(t, std::forward<func>(f));
}
template<ssize_t i = -1,
class func,
class... args>
constexpr
typename std::enable_if<(i == -1), void>::type
rfor_each(std::tuple<args...> &t,
func&& f)
{
constexpr const ssize_t size
{
std::tuple_size<std::tuple<args...>>::value
};
rfor_each<size>(t, std::forward<func>(f));
}
//
// Iteration of a tuple until() style: your closure returns true to continue, false
// to break. until() then remains true to the end, or returns false if not.
template<size_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == std::tuple_size<std::tuple<args...>>::value, bool>::type
until(std::tuple<args...> &t,
func&& f)
{
return true;
}
template<size_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == std::tuple_size<std::tuple<args...>>::value, bool>::type
until(const std::tuple<args...> &t,
func&& f)
{
return true;
}
template<size_t i = 0,
class func,
class... args>
constexpr
typename std::enable_if<i < std::tuple_size<std::tuple<args...>>::value, bool>::type
until(std::tuple<args...> &t,
func&& f)
{
using value_type = typename std::tuple_element<i, std::tuple<args...>>::type;
return f(static_cast<value_type &>(std::get<i>(t)))? until<i+1>(t, f) : false;
}
template<size_t i = 0,
class func,
class... args>
constexpr
typename std::enable_if<i < std::tuple_size<std::tuple<args...>>::value, bool>::type
until(const std::tuple<args...> &t,
func&& f)
{
using value_type = typename std::tuple_element<i, std::tuple<args...>>::type;
return f(static_cast<const value_type &>(std::get<i>(t)))? until<i+1>(t, f) : false;
}
//
// Circuits for reverse iteration of a tuple
//
// runtil(tuple, [](auto&& elem) -> bool { ... });
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == 0, bool>::type
runtil(const std::tuple<args...> &t,
func&& f)
{
return true;
}
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == 0, bool>::type
runtil(std::tuple<args...> &t,
func&& f)
{
return true;
}
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<(i > 0), bool>::type
runtil(const std::tuple<args...> &t,
func&& f)
{
return f(std::get<i - 1>(t))? runtil<i - 1>(t, f) : false;
}
template<ssize_t i,
class func,
class... args>
constexpr
typename std::enable_if<(i > 0), bool>::type
runtil(std::tuple<args...> &t,
func&& f)
{
return f(std::get<i - 1>(t))? runtil<i - 1>(t, f) : false;
}
template<ssize_t i = -1,
class func,
class... args>
constexpr
typename std::enable_if<(i == -1), bool>::type
runtil(const std::tuple<args...> &t,
func&& f)
{
constexpr const auto size
{
std::tuple_size<std::tuple<args...>>::value
};
return runtil<size>(t, std::forward<func>(f));
}
template<ssize_t i = -1,
class func,
class... args>
constexpr
typename std::enable_if<(i == -1), bool>::type
runtil(std::tuple<args...> &t,
func&& f)
{
constexpr const auto size
{
std::tuple_size<std::tuple<args...>>::value
};
return runtil<size>(t, std::forward<func>(f));
}
//
// Kronecker delta
//
template<size_t j,
size_t i,
class func,
class... args>
constexpr
typename std::enable_if<i == j, void>::type
kronecker_delta(const std::tuple<args...> &t,
func&& f)
{
using value_type = typename std::tuple_element<i, std::tuple<args...>>::type;
f(static_cast<const value_type &>(std::get<i>(t)));
}
template<size_t i,
size_t j,
class func,
class... args>
constexpr
typename std::enable_if<i == j, void>::type
kronecker_delta(std::tuple<args...> &t,
func&& f)
{
using value_type = typename std::tuple_element<i, std::tuple<args...>>::type;
f(static_cast<value_type &>(std::get<i>(t)));
}
template<size_t j,
size_t i = 0,
class func,
class... args>
constexpr
typename std::enable_if<(i < j), void>::type
kronecker_delta(const std::tuple<args...> &t,
func&& f)
{
kronecker_delta<j, i + 1>(t, std::forward<func>(f));
}
template<size_t j,
size_t i = 0,
class func,
class... args>
constexpr
typename std::enable_if<(i < j), void>::type
kronecker_delta(std::tuple<args...> &t,
func&& f)
{
kronecker_delta<j, i + 1>(t, std::forward<func>(f));
}
// For conforming enums include a _NUM_ as the last element,
// then num_of<my_enum>() works
template<class Enum>
constexpr
typename std::underlying_type<Enum>::type
num_of()
{
return static_cast<typename std::underlying_type<Enum>::type>(Enum::_NUM_);
}
// Iteration of a num_of() conforming enum
template<class Enum>
typename std::enable_if<std::is_enum<Enum>::value, void>::type
for_each(const std::function<void (const Enum &)> &func)
{
for(size_t i(0); i < num_of<Enum>(); ++i)
func(static_cast<Enum>(i));
}
/**
* flag-enum utilities
*
* This relaxes the strong typing of enums to allow bitflags with operations on the elements
* with intuitive behavior.
*
* If the project desires absolute guarantees on the strong enum typing then this can be tucked
* away in some namespace and imported into select scopes instead.
*/
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, Enum>::type
operator~(const Enum &a)
{
using enum_t = typename std::underlying_type<Enum>::type;
return static_cast<Enum>(~static_cast<enum_t>(a));
}
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, bool>::type
operator!(const Enum &a)
{
using enum_t = typename std::underlying_type<Enum>::type;
return !static_cast<enum_t>(a);
}
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, Enum>::type
operator|(const Enum &a, const Enum &b)
{
using enum_t = typename std::underlying_type<Enum>::type;
return static_cast<Enum>(static_cast<enum_t>(a) | static_cast<enum_t>(b));
}
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, Enum>::type
operator&(const Enum &a, const Enum &b)
{
using enum_t = typename std::underlying_type<Enum>::type;
return static_cast<Enum>(static_cast<enum_t>(a) & static_cast<enum_t>(b));
}
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, Enum>::type
operator^(const Enum &a, const Enum &b)
{
using enum_t = typename std::underlying_type<Enum>::type;
return static_cast<Enum>(static_cast<enum_t>(a) ^ static_cast<enum_t>(b));
}
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, Enum &>::type
operator|=(Enum &a, const Enum &b)
{
using enum_t = typename std::underlying_type<Enum>::type;
return (a = (a | b));
}
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, Enum &>::type
operator&=(Enum &a, const Enum &b)
{
using enum_t = typename std::underlying_type<Enum>::type;
return (a = (a & b));
}
template<class Enum>
constexpr
typename std::enable_if<std::is_enum<Enum>::value, Enum &>::type
operator^=(Enum &a, const Enum &b)
{
using enum_t = typename std::underlying_type<Enum>::type;
return (a = (a ^ b));
}
inline size_t
size(std::ostream &s)
{
const auto cur(s.tellp());
s.seekp(0, std::ios::end);
const auto ret(s.tellp());
s.seekp(cur, std::ios::beg);
return ret;
}
template<class T>
auto
string(const T &s)
{
std::stringstream ss;
return static_cast<std::stringstream &>(ss << s).str();
}
inline auto
string(const char *const &buf, const size_t &size)
{
return std::string{buf, size};
}
inline auto
string(const uint8_t *const &buf, const size_t &size)
{
return string(reinterpret_cast<const char *>(buf), size);
}
constexpr size_t
hash(const char *const &str,
const size_t i = 0)
{
return !str[i]? 7681ULL : (hash(str, i+1) * 33ULL) ^ str[i];
}
inline size_t
hash(const std::string_view &str,
const size_t i = 0)
{
return i >= str.size()? 7681ULL : (hash(str, i+1) * 33ULL) ^ str.at(i);
}
inline size_t
hash(const std::string &str,
const size_t i = 0)
{
return i >= str.size()? 7681ULL : (hash(str, i+1) * 33ULL) ^ str.at(i);
}
constexpr size_t
hash(const char16_t *const &str,
const size_t i = 0)
{
return !str[i]? 7681ULL : (hash(str, i+1) * 33ULL) ^ str[i];
}
inline size_t
hash(const std::u16string &str,
const size_t i = 0)
{
return i >= str.size()? 7681ULL : (hash(str, i+1) * 33ULL) ^ str.at(i);
}
/***
* C++14 user defined literals
*
* These are very useful for dealing with space. Simply write 8_MiB and it's
* as if a macro turned that into (8 * 1024 * 1024) at compile time.
*/
#define IRCD_UNIT_LITERAL_LL(name, morphism) \
constexpr auto \
operator"" _ ## name(const unsigned long long val) \
{ \
return (morphism); \
}
#define IRCD_UNIT_LITERAL_LD(name, morphism) \
constexpr auto \
operator"" _ ## name(const long double val) \
{ \
return (morphism); \
}
// IEC unit literals
IRCD_UNIT_LITERAL_LL( B, val )
IRCD_UNIT_LITERAL_LL( KiB, val * 1024LL )
IRCD_UNIT_LITERAL_LL( MiB, val * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_LL( GiB, val * 1024LL * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_LL( TiB, val * 1024LL * 1024LL * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_LL( PiB, val * 1024LL * 1024LL * 1024LL * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_LL( EiB, val * 1024LL * 1024LL * 1024LL * 1024LL * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_LD( B, val )
IRCD_UNIT_LITERAL_LD( KiB, val * 1024.0L )
IRCD_UNIT_LITERAL_LD( MiB, val * 1024.0L * 1024.0L )
IRCD_UNIT_LITERAL_LD( GiB, val * 1024.0L * 1024.0L * 1024.0L )
IRCD_UNIT_LITERAL_LD( TiB, val * 1024.0L * 1024.0L * 1024.0L * 1024.0L )
IRCD_UNIT_LITERAL_LD( PiB, val * 1024.0L * 1024.0L * 1024.0L * 1024.0L * 1024.0L )
IRCD_UNIT_LITERAL_LD( EiB, val * 1024.0L * 1024.0L * 1024.0L * 1024.0L * 1024.0L * 1024.0L )
// SI unit literals
IRCD_UNIT_LITERAL_LL( KB, val * 1000LL )
IRCD_UNIT_LITERAL_LL( MB, val * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_LL( GB, val * 1000LL * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_LL( TB, val * 1000LL * 1000LL * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_LL( PB, val * 1000LL * 1000LL * 1000LL * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_LL( EB, val * 1000LL * 1000LL * 1000LL * 1000LL * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_LD( KB, val * 1000.0L )
IRCD_UNIT_LITERAL_LD( MB, val * 1000.0L * 1000.0L )
IRCD_UNIT_LITERAL_LD( GB, val * 1000.0L * 1000.0L * 1000.0L )
IRCD_UNIT_LITERAL_LD( TB, val * 1000.0L * 1000.0L * 1000.0L * 1000.0L )
IRCD_UNIT_LITERAL_LD( PB, val * 1000.0L * 1000.0L * 1000.0L * 1000.0L * 1000.0L )
IRCD_UNIT_LITERAL_LD( EB, val * 1000.0L * 1000.0L * 1000.0L * 1000.0L * 1000.0L * 1000.0L )
/* Output the sizeof a structure at compile time.
* This stops the compiler with an error (good) containing the size of the target
* in the message.
*
* example: struct foo {}; IRCD_TEST_SIZEOF(foo)
*/
template<size_t SIZE>
struct _TEST_SIZEOF_;
#define IRCD_TEST_SIZEOF(name) \
ircd::util::_TEST_SIZEOF_<sizeof(name)> _test_;
/* This is a template alternative to nothrow overloads, which
* allows keeping the function arguments sanitized of the thrownness.
*/
template<class exception_t>
constexpr bool
is_nothrow()
{
return std::is_same<exception_t, std::nothrow_t>::value;
}
template<class exception_t = std::nothrow_t,
class return_t = bool>
using nothrow_overload = typename std::enable_if<is_nothrow<exception_t>(), return_t>::type;
template<class exception_t,
class return_t = void>
using throw_overload = typename std::enable_if<!is_nothrow<exception_t>(), return_t>::type;
//
// Test if type is forward declared or complete
//
template<class T,
class = void>
struct is_complete
:std::false_type
{
};
template<class T>
struct is_complete<T, decltype(void(sizeof(T)))>
:std::true_type
{
};
//
// Convenience constexprs for iterators
//
template<class It>
constexpr auto
is_iterator()
{
return std::is_base_of<typename std::iterator_traits<It>::value_type, It>::value;
}
template<class It>
constexpr auto
is_forward_iterator()
{
return std::is_base_of<std::forward_iterator_tag, typename std::iterator_traits<It>::iterator_category>::value;
}
template<class It>
constexpr auto
is_input_iterator()
{
return std::is_base_of<std::forward_iterator_tag, typename std::iterator_traits<It>::iterator_category>::value;
}
// std::next with out_of_range exception
template<class It>
typename std::enable_if<is_forward_iterator<It>() || is_input_iterator<It>(), It>::type
at(It &&start,
It &&stop,
ssize_t i)
{
for(; start != stop; --i, std::advance(start, 1))
if(!i)
return start;
throw std::out_of_range("at(a, b, i): 'i' out of range");
}
//
// Some functors for STL
//
template<class container>
struct keys
{
auto &operator()(typename container::reference v) const
{
return v.first;
}
};
template<class container>
struct values
{
auto &operator()(typename container::reference v) const
{
return v.second;
}
};
//
// Customized std::string_view (experimental TS / C++17)
//
// This class adds iterator-based (char*, char*) construction to std::string_view which otherwise
// takes traditional (char*, size_t) arguments. This allows boost::spirit grammars to create
// string_view's using the raw[] directive achieving zero-copy/zero-allocation parsing.
//
struct string_view
:std::string_view
{
// (non-standard) our faux insert stub
// Tricks boost::spirit into thinking this is mutable string (hint: it's not).
// Instead, the raw[] directive in Qi grammar will use the iterator constructor only.
// __attribute__((error("string_view is not insertable (hint: use raw[] directive)")))
void insert(const iterator &, const char &)
{
assert(0);
}
// (non-standard) our iterator-based assign
string_view &assign(const char *const &begin, const char *const &end)
{
*this = std::string_view{begin, size_t(std::distance(begin, end))};
return *this;
}
// (non-standard) intuitive wrapper for remove_suffix.
// Unlike std::string, we can cheaply involve a reference to the removed character
// which still exists.
const char &pop_back()
{
const char &ret(back());
remove_suffix(1);
return ret;
}
// (non-standard) intuitive wrapper for remove_prefix.
// Unlike std::string, we can cheaply involve a reference to the removed character
// which still exists.
const char &pop_front()
{
const char &ret(front());
remove_prefix(1);
return ret;
}
// (non-standard) our iterator-based constructor
string_view(const char *const &begin, const char *const &end)
:std::string_view{begin, size_t(std::distance(begin, end))}
{}
// (non-standard) our array based constructor
template<size_t SIZE>
string_view(const std::array<char, SIZE> &array)
:string_view
{
array.data(), std::find(array.begin(), array.end(), '\0')
}{}
// (non-standard) our buffer based constructor
template<size_t SIZE>
string_view(const char (&buf)[SIZE])
:string_view
{
buf, std::find(buf, buf + SIZE, '\0')
}{}
// Required due to current instability in stdlib
//string_view(const std::experimental::string_view &esv)
//:std::string_view{esv}
//{}
// Required due to current instability in stdlib
string_view(const std::experimental::fundamentals_v1::basic_string_view<char> &bsv)
:std::string_view{bsv}
{}
string_view()
:std::string_view{}
{}
using std::string_view::string_view;
};
template<class T>
struct vector_view
{
T *_data { nullptr };
T *_stop { nullptr };
public:
T *data() const { return _data; }
size_t size() const { return std::distance(_data, _stop); }
bool empty() const { return !size(); }
const T *begin() const { return data(); }
const T *end() const { return _stop; }
const T *cbegin() { return data(); }
const T *cend() { return _stop; }
T *begin() { return data(); }
T *end() { return _stop; }
const T &operator[](const size_t &pos) const
{
return *(data() + pos);
}
T &operator[](const size_t &pos)
{
return *(data() + pos);
}
const T &at(const size_t &pos) const
{
if(unlikely(pos >= size()))
throw std::out_of_range();
return operator[](pos);
}
T &at(const size_t &pos)
{
if(unlikely(pos >= size()))
throw std::out_of_range();
return operator[](pos);
}
vector_view(T *const &start, T *const &stop)
:_data{start}
,_stop{stop}
{}
vector_view(T *const &start, const size_t &size)
:_data{start}
,_stop{start + size}
{}
template<class U,
class A>
vector_view(std::vector<U, A> &v)
:vector_view{v.data(), v.size()}
{}
template<size_t SIZE>
vector_view(T (&buffer)[SIZE])
:vector_view{std::addressof(buffer), SIZE}
{}
template<size_t SIZE>
vector_view(std::array<T, SIZE> &array)
:vector_view{array.data(), array.size()}
{}
vector_view() = default;
};
//
// Convenience cast a type (ex. an integer) into and out of a string_view
//
// string_view -> bytes
template<class T = string_view>
struct byte_view
{
string_view s;
operator const T &() const
{
return *reinterpret_cast<const T *>(s.data());
}
byte_view(const string_view &s)
:s{s}
{
if(unlikely(sizeof(T) != s.size()))
throw std::bad_cast();
}
// bytes -> bytes (completeness)
byte_view(const T &t)
:s{byte_view<string_view>{t}}
{}
};
// bytes -> string_view
template<>
struct byte_view<string_view>
:string_view
{
template<class T>
byte_view(const T &t)
:string_view{reinterpret_cast<const char *>(&t), sizeof(T)}
{}
};
// string_view -> string_view (completeness)
template<> inline
byte_view<string_view>::byte_view(const string_view &t)
:string_view{t}
{}
//
// Error-checking closure for POSIX system calls. Note the usage is
// syscall(read, foo, bar, baz) not a macro like syscall(read(foo, bar, baz));
//
template<class function,
class... args>
auto
syscall(function&& f,
args&&... a)
{
const auto ret(f(a...));
if(unlikely(long(ret) == -1))
throw std::system_error(errno, std::system_category());
return ret;
}
//
// Similar to a va_list, but conveying std-c++ type data acquired from a variadic template
// parameter pack acting as the ...) elipsis. This is used to implement fmt::snprintf(),
// exceptions and logger et al in their respective translation units rather than the header
// files.
//
// Limitations: The choice of a fixed array of N is because std::initializer_list doesn't
// work here and other containers may be heavy in this context. Ideas to improve this are
// welcome.
//
const size_t VA_RTTI_MAX_SIZE = 12;
struct va_rtti
:std::array<std::pair<const void *, const std::type_info *>, VA_RTTI_MAX_SIZE>
{
using base_type = std::array<value_type, VA_RTTI_MAX_SIZE>;
static constexpr size_t max_size()
{
return std::tuple_size<base_type>();
}
size_t argc;
const size_t &size() const
{
return argc;
}
template<class... Args>
va_rtti(Args&&... args)
:base_type
{{
std::make_pair(std::addressof(args), std::addressof(typeid(Args)))...
}}
,argc
{
sizeof...(args)
}
{
assert(argc <= max_size());
}
};
static_assert
(
sizeof(va_rtti) == (va_rtti::max_size() * 16) + 8,
"va_rtti should be (8 + 8) * N + 8;"
" where 8 + 8 are the two pointers carrying the argument and its type data;"
" where N is the max arguments;"
" where the final + 8 bytes holds the actual number of arguments passed;"
);
//
// To collapse pairs of iterators down to a single type
//
template<class T>
using iterators = std::pair<typename T::iterator, typename T::iterator>;
template<class T>
using const_iterators = std::pair<typename T::const_iterator, typename T::const_iterator>;
template<class T>
typename T::iterator
begin(const iterators<T> &i)
{
return i.first;
}
template<class T>
typename T::iterator
end(const iterators<T> &i)
{
return i.second;
}
template<class T>
typename T::const_iterator
begin(const const_iterators<T> &ci)
{
return ci.first;
}
template<class T>
typename T::const_iterator
end(const const_iterators<T> &ci)
{
return ci.second;
}
//
// For objects using the pattern of adding their own instance to a container
// in their constructor, storing an iterator as a member, and then removing
// themselves using the iterator in their destructor. It is unsafe to do that.
// Use this instead.
//
template<class container,
class iterator = typename container::iterator>
struct unique_iterator
{
container *c;
iterator it;
unique_iterator(container &c, iterator it)
:c{&c}
,it{std::move(it)}
{}
unique_iterator()
:c{nullptr}
{}
unique_iterator(const unique_iterator &) = delete;
unique_iterator(unique_iterator &&o)
:c{std::move(o.c)}
,it{std::move(o.it)}
{
o.c = nullptr;
}
~unique_iterator() noexcept
{
if(c)
c->erase(it);
}
};
template<class container>
struct unique_const_iterator
:unique_iterator<container, typename container::const_iterator>
{
using iterator_type = typename container::const_iterator;
using unique_iterator<container, iterator_type>::unique_iterator;
};
//
// Get the index of a tuple element by address at runtime
//
template<class tuple>
size_t
indexof(tuple &t, const void *const &ptr)
{
size_t ret(0);
const auto closure([&ret, &ptr]
(auto &elem)
{
if(reinterpret_cast<const void *>(std::addressof(elem)) == ptr)
return false;
++ret;
return true;
});
if(unlikely(until(t, closure)))
throw std::out_of_range("no member of this tuple with that address");
return ret;
}
//
// Tuple layouts are not standard layouts; we can only do this at runtime
//
template<size_t index,
class tuple>
off_t
tuple_offset(const tuple &t)
{
return
{
reinterpret_cast<const uint8_t *>(std::addressof(std::get<index>(t))) -
reinterpret_cast<const uint8_t *>(std::addressof(t))
};
}
//
// Compile-time comparison of string literals
//
constexpr bool
_constexpr_equal(const char *a,
const char *b)
{
return *a == *b && (*a == '\0' || _constexpr_equal(a + 1, b + 1));
}
inline auto
operator!(const std::string &str)
{
return str.empty();
}
inline auto
operator!(const std::string_view &str)
{
return str.empty();
}
inline auto
operator!(const string_view &str)
{
return str.empty();
}
//
// Iterator based until() matching std::for_each except the function
// returns a bool to continue rather than void.
//
template<class it_a,
class it_b,
class boolean_function>
bool
until(it_a a,
const it_b &b,
boolean_function&& f)
{
for(; a != b; ++a)
if(!f(*a))
return false;
return true;
}
} // namespace util
} // namespace ircd
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