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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
/// Tools for developers
namespace ircd::util
{
}
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))
/* 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_;
// 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))))
///
/// 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.
///
/// (Internal) Defines a unit literal with an unsigned long long basis.
///
#define IRCD_UNIT_LITERAL_UL(name, morphism) \
constexpr auto \
operator"" _ ## name(const unsigned long long val) \
{ \
return (morphism); \
}
/// (Internal) Defines a unit literal with a signed long long basis
///
#define IRCD_UNIT_LITERAL_LL(name, morphism) \
constexpr auto \
operator"" _ ## name(const long long val) \
{ \
return (morphism); \
}
/// (Internal) Defines a unit literal with a long double basis
///
#define IRCD_UNIT_LITERAL_LD(name, morphism) \
constexpr auto \
operator"" _ ## name(const long double val) \
{ \
return (morphism); \
}
// IEC unit literals
IRCD_UNIT_LITERAL_UL( B, val )
IRCD_UNIT_LITERAL_UL( KiB, val * 1024LL )
IRCD_UNIT_LITERAL_UL( MiB, val * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_UL( GiB, val * 1024LL * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_UL( TiB, val * 1024LL * 1024LL * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_UL( PiB, val * 1024LL * 1024LL * 1024LL * 1024LL * 1024LL )
IRCD_UNIT_LITERAL_UL( 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_UL( KB, val * 1000LL )
IRCD_UNIT_LITERAL_UL( MB, val * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_UL( GB, val * 1000LL * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_UL( TB, val * 1000LL * 1000LL * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_UL( PB, val * 1000LL * 1000LL * 1000LL * 1000LL * 1000LL )
IRCD_UNIT_LITERAL_UL( 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 )
///
/// Fundamental scope-unwind utilities establishing actions during destruction
///
/// Unconditionally executes the provided code when the object goes out of scope.
///
struct unwind
{
struct nominal;
struct exceptional;
const std::function<void ()> func;
template<class F>
unwind(F &&func)
:func{std::forward<F>(func)}
{}
unwind(const unwind &) = delete;
unwind &operator=(const unwind &) = delete;
~unwind() noexcept
{
func();
}
};
/// Executes function only if the unwind takes place without active exception
///
/// The function is expected to be executed and the likely() should pipeline
/// that branch and make this device cheaper to use under normal circumstances.
///
struct unwind::nominal
{
const std::function<void ()> func;
template<class F>
nominal(F &&func)
:func{std::forward<F>(func)}
{}
~nominal() noexcept
{
if(likely(!std::uncaught_exception()))
func();
}
nominal(const nominal &) = delete;
};
/// Executes function only if unwind is taking place because exception thrown
///
/// The unlikely() intends for the cost of a branch misprediction to be paid
/// for fetching and executing this function. This is because we strive to
/// optimize the pipeline for the nominal path, making this device as cheap
/// as possible to use.
///
struct unwind::exceptional
{
const std::function<void ()> func;
template<class F>
exceptional(F &&func)
:func{std::forward<F>(func)}
{}
~exceptional() noexcept
{
if(unlikely(std::uncaught_exception()))
func();
}
exceptional(const exceptional &) = delete;
};
template<class T>
using custom_ptr = std::unique_ptr<T, std::function<void (T *) noexcept>>;
// 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));
}
template<class Enum,
class it>
typename std::enable_if<std::is_enum<Enum>::value, typename std::underlying_type<Enum>::type>::type
combine_flags(const it &begin,
const it &end)
{
using type = typename std::underlying_type<Enum>::type;
return std::accumulate(begin, end, type(0), []
(auto ret, const auto &val)
{
return ret |= type(val);
});
}
template<class Enum>
typename std::enable_if<std::is_enum<Enum>::value, typename std::underlying_type<Enum>::type>::type
combine_flags(const std::initializer_list<Enum> &list)
{
return combine_flags<Enum>(begin(list), end(list));
}
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<size_t SIZE>
constexpr size_t
size(const char (&buf)[SIZE])
{
return SIZE;
}
template<size_t SIZE>
constexpr size_t
size(const std::array<const char, SIZE> &buf)
{
return SIZE;
}
template<size_t SIZE>
constexpr size_t
size(const std::array<char, SIZE> &buf)
{
return SIZE;
}
template<class T>
constexpr typename std::enable_if<std::is_integral<T>::value, size_t>::type
size(const T &val)
{
return sizeof(T);
}
template<size_t SIZE>
constexpr const char *
data(const char (&buf)[SIZE])
{
return buf;
}
template<size_t SIZE>
constexpr char *
data(char (&buf)[SIZE])
{
return buf;
}
template<class T>
constexpr typename std::enable_if<std::is_pod<T>::value, const uint8_t *>::type
data(const T &val)
{
return reinterpret_cast<const uint8_t *>(&val);
}
template<class T>
constexpr typename std::enable_if<std::is_pod<T>::value, uint8_t *>::type
data(T &val)
{
return reinterpret_cast<uint8_t *>(&val);
}
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);
}
//
// stringstream buffer set macros
//
inline std::string &
pubsetbuf(std::stringstream &ss,
std::string &s)
{
auto *const &data
{
const_cast<char *>(s.data())
};
ss.rdbuf()->pubsetbuf(data, s.size());
return s;
}
inline std::string &
pubsetbuf(std::stringstream &ss,
std::string &s,
const size_t &size)
{
s.resize(size, char{});
return pubsetbuf(ss, s);
}
inline std::string &
resizebuf(std::stringstream &ss,
std::string &s)
{
s.resize(ss.tellp());
return s;
}
/* 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
{};
//
// Test if type is a specialization of a template
//
template<class,
template<class...>
class>
struct is_specialization_of
:std::false_type
{};
template<template<class...>
class T,
class... args>
struct is_specialization_of<T<args...>, 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;
}
};
//
// 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<int ERROR_CODE = -1,
class function,
class... args>
auto
syscall(function&& f,
args&&... a)
-> typename std::enable_if<std::is_same<int, decltype(f(a...))>::value, int>::type
{
const int ret
{
f(std::forward<args>(a)...)
};
if(unlikely(ret == ERROR_CODE))
throw std::system_error(errno, std::system_category());
return ret;
}
//
// 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<int ERROR_CODE = -1,
class function,
class... args>
auto
uninterruptible_syscall(function&& f,
args&&... a)
-> typename std::enable_if<std::is_same<int, decltype(f(a...))>::value, int>::type
{
int ret; do
{
ret = f(std::forward<args>(a)...);
}
while(unlikely(ret == ERROR_CODE && errno == EINTR));
if(unlikely(ret == ERROR_CODE))
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>
struct iterpair
:std::pair<T, T>
{
using std::pair<T, T>::pair;
};
template<class T>
T &
begin(iterpair<T> &i)
{
return std::get<0>(i);
}
template<class T>
T &
end(iterpair<T> &i)
{
return std::get<1>(i);
}
template<class T>
const T &
begin(const iterpair<T> &i)
{
return std::get<0>(i);
}
template<class T>
const T &
end(const iterpair<T> &i)
{
return std::get<1>(i);
}
//
// To collapse pairs of iterators down to a single type
// typed by an object with iterator typedefs.
//
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; or better, use ircd::instance_list<>
//
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) noexcept
:c{std::move(o.c)}
,it{std::move(o.it)}
{
o.c = nullptr;
}
unique_iterator &operator=(const unique_iterator &) = delete;
unique_iterator &operator=(unique_iterator &&o) noexcept
{
this->~unique_iterator();
c = std::move(o.c);
it = std::move(o.it);
o.c = nullptr;
return *this;
}
~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;
};
/// The instance_list pattern is where every instance of a class registers
/// itself in a static list of all instances and removes itself on dtor.
/// IRCd Ex. All clients use instance_list so all clients can be listed for
/// an administrator or be interrupted and disconnected on server shutdown.
///
/// `struct myobj : ircd::instance_list<myobj> {};`
///
/// * The creator of the class no longer has to manually specify what is
/// defined here using unique_iterator; however, one still must provide
/// linkage for the static list.
///
/// * The container pointer used by unique_iterator is eliminated here
/// because of the static list.
///
template<class T>
struct instance_list
{
static std::list<T *> list;
protected:
typename decltype(list)::iterator it;
instance_list(typename decltype(list)::iterator it)
:it{std::move(it)}
{}
instance_list()
:it{list.emplace(end(list), static_cast<T *>(this))}
{}
instance_list(const instance_list &) = delete;
instance_list(instance_list &&o) noexcept
:it{std::move(o.it)}
{
o.it = end(list);
}
instance_list &operator=(const instance_list &) = delete;
instance_list &operator=(instance_list &&o) noexcept
{
std::swap(it, o.it);
return *this;
}
~instance_list() noexcept
{
if(it != end(list))
list.erase(it);
}
};
//
// 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();
}
//
// 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;
}
/// Convenience loop to test std::is* on a character sequence
template<int (&test)(int) = std::isprint>
ssize_t
ctype(const char *begin,
const char *const &end)
{
size_t i(0);
for(; begin != end; ++begin, ++i)
if(!test(static_cast<unsigned char>(*begin)))
return i;
return -1;
}
template<class lockable>
struct unlock_guard
{
lockable &l;
unlock_guard(lockable &l)
:l{l}
{
l.unlock();
}
~unlock_guard() noexcept
{
l.lock();
}
};
template<class T>
constexpr bool
is_bool()
{
using type = typename std::remove_reference<T>::type;
return std::is_same<type, bool>::value;
}
template<class T>
constexpr bool
is_number()
{
using type = typename std::remove_reference<T>::type;
return std::is_arithmetic<type>::value;
}
template<class T>
constexpr bool
is_floating()
{
using type = typename std::remove_reference<T>::type;
return is_number<T>() && std::is_floating_point<type>();
}
template<class T>
constexpr bool
is_integer()
{
return is_number<T>() && !is_floating<T>();
}
struct is_zero
{
template<class T>
typename std::enable_if
<
is_bool<T>(),
bool>::type
test(const bool &value)
const
{
return !value;
}
template<class T>
typename std::enable_if
<
is_integer<T>() &&
!is_bool<T>(),
bool>::type
test(const size_t &value)
const
{
return value == 0;
}
template<class T>
typename std::enable_if
<
is_floating<T>(),
bool>::type
test(const double &value)
const
{
return !(value > 0.0 || value < 0.0);
}
template<class T>
bool operator()(T&& t)
const
{
return test<T>(std::forward<T>(t));
}
};
constexpr bool
is_powerof2(const long long v)
{
return v && !(v & (v - 1LL));
}
template<class T>
T &
bswap(T *const &val)
{
assert(val != nullptr);
std::reverse(data(*val), data(*val) + size(*val));
return *val;
}
template<class T>
T
bswap(const T &val)
{
T ret;
std::reverse_copy(data(val), data(val) + size(val), data(ret));
return ret;
}
} // namespace util
} // namespace ircd
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