/*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2016 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
// @author: Andrei Alexandrescu
-#ifndef FOLLY_BASE_TRAITS_H_
-#define FOLLY_BASE_TRAITS_H_
+#pragma once
#include <memory>
#include <limits>
#include <type_traits>
-
+#include <functional>
+
+#include <folly/Portability.h>
+
+// libc++ doesn't provide this header, nor does msvc
+#ifdef FOLLY_HAVE_BITS_CXXCONFIG_H
+// This file appears in two locations: inside fbcode and in the
+// libstdc++ source code (when embedding fbstring as std::string).
+// To aid in this schizophrenic use, two macros are defined in
+// c++config.h:
+// _LIBSTDCXX_FBSTRING - Set inside libstdc++. This is useful to
+// gate use inside fbcode v. libstdc++
#include <bits/c++config.h>
+#endif
#include <boost/type_traits.hpp>
-#include <boost/mpl/and.hpp>
#include <boost/mpl/has_xxx.hpp>
-#include <boost/mpl/not.hpp>
namespace folly {
namespace traits_detail {
-#define FOLLY_HAS_TRUE_XXX(name) \
- BOOST_MPL_HAS_XXX_TRAIT_DEF(name); \
- template <class T> struct name ## _is_true \
- : std::is_same<typename T::name, std::true_type> {}; \
- template <class T> struct has_true_ ## name \
- : std::conditional< \
- has_ ## name <T>::value, \
- name ## _is_true<T>, \
- std::false_type \
- >:: type {};
+#define FOLLY_HAS_TRUE_XXX(name) \
+ BOOST_MPL_HAS_XXX_TRAIT_DEF(name) \
+ template <class T> \
+ struct name##_is_true : std::is_same<typename T::name, std::true_type> {}; \
+ template <class T> \
+ struct has_true_##name : std::conditional< \
+ has_##name<T>::value, \
+ name##_is_true<T>, \
+ std::false_type>::type {};
FOLLY_HAS_TRUE_XXX(IsRelocatable)
FOLLY_HAS_TRUE_XXX(IsZeroInitializable)
traits_detail::has_true_IsZeroInitializable<T>::value
> {};
+template <typename...>
+struct Conjunction : std::true_type {};
+template <typename T>
+struct Conjunction<T> : T {};
+template <typename T, typename... TList>
+struct Conjunction<T, TList...>
+ : std::conditional<T::value, Conjunction<TList...>, T>::type {};
+
+template <typename...>
+struct Disjunction : std::false_type {};
+template <typename T>
+struct Disjunction<T> : T {};
+template <typename T, typename... TList>
+struct Disjunction<T, TList...>
+ : std::conditional<T::value, T, Disjunction<TList...>>::type {};
+
+template <typename T>
+struct Negation : std::integral_constant<bool, !T::value> {};
+
} // namespace folly
/**
* although that is not guaranteed by the standard.
*/
-namespace std {
+FOLLY_NAMESPACE_STD_BEGIN
template <class T, class U>
struct pair;
#ifndef _GLIBCXX_USE_FB
+FOLLY_GLIBCXX_NAMESPACE_CXX11_BEGIN
template <class T, class R, class A>
class basic_string;
+FOLLY_GLIBCXX_NAMESPACE_CXX11_END
#else
template <class T, class R, class A, class S>
class basic_string;
class vector;
template <class T, class A>
class deque;
+FOLLY_GLIBCXX_NAMESPACE_CXX11_BEGIN
template <class T, class A>
class list;
+FOLLY_GLIBCXX_NAMESPACE_CXX11_END
template <class T, class C, class A>
class set;
template <class K, class V, class C, class A>
template <class T>
class shared_ptr;
-}
+FOLLY_NAMESPACE_STD_END
namespace boost {
template <class T, class U>
struct has_nothrow_constructor< std::pair<T, U> >
- : ::boost::mpl::and_< has_nothrow_constructor<T>,
- has_nothrow_constructor<U> > {};
+ : std::integral_constant<bool,
+ has_nothrow_constructor<T>::value &&
+ has_nothrow_constructor<U>::value> {};
} // namespace boost
// STL commonly-used types
template <class T, class U>
-struct IsRelocatable< std::pair<T, U> >
- : ::boost::mpl::and_< IsRelocatable<T>, IsRelocatable<U> > {};
+struct IsRelocatable< std::pair<T, U> >
+ : std::integral_constant<bool,
+ IsRelocatable<T>::value &&
+ IsRelocatable<U>::value> {};
// Is T one of T1, T2, ..., Tn?
template <class T, class... Ts>
enum { value = std::is_same<T, T1>::value || IsOneOf<T, Ts...>::value };
};
-/**
- * A traits class to check for incomplete types.
- *
- * Example:
- *
- * struct FullyDeclared {}; // complete type
- * struct ForwardDeclared; // incomplete type
- *
- * is_complete<int>::value // evaluates to true
- * is_complete<FullyDeclared>::value // evaluates to true
- * is_complete<ForwardDeclared>::value // evaluates to false
- *
- * struct ForwardDeclared {}; // declared, at last
- *
- * is_complete<ForwardDeclared>::value // now it evaluates to true
- *
- * @author: Marcelo Juchem <marcelo@fb.com>
- */
-template <typename T>
-class is_complete {
- template <unsigned long long> struct sfinae {};
- template <typename U>
- constexpr static bool test(sfinae<sizeof(U)>*) { return true; }
- template <typename> constexpr static bool test(...) { return false; }
-public:
- constexpr static bool value = test<T>(nullptr);
-};
-
/*
* Complementary type traits for integral comparisons.
*
template <typename T>
struct is_negative_impl<T, false> {
- constexpr static bool check(T x) { return false; }
+ constexpr static bool check(T) { return false; }
};
-template <typename RHS, RHS rhs, typename LHS>
-bool less_than_impl(
- typename std::enable_if<
- (rhs <= std::numeric_limits<LHS>::max()
- && rhs > std::numeric_limits<LHS>::min()),
- LHS
- >::type const lhs
-) {
- return lhs < rhs;
-}
+// folly::to integral specializations can end up generating code
+// inside what are really static ifs (not executed because of the templated
+// types) that violate -Wsign-compare and/or -Wbool-compare so suppress them
+// in order to not prevent all calling code from using it.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsign-compare"
+#if __GNUC_PREREQ(5, 0)
+#pragma GCC diagnostic ignored "-Wbool-compare"
+#endif
template <typename RHS, RHS rhs, typename LHS>
-bool less_than_impl(
- typename std::enable_if<
- (rhs > std::numeric_limits<LHS>::max()),
- LHS
- >::type const
-) {
- return true;
+bool less_than_impl(LHS const lhs) {
+ return
+ rhs > std::numeric_limits<LHS>::max() ? true :
+ rhs <= std::numeric_limits<LHS>::min() ? false :
+ lhs < rhs;
}
template <typename RHS, RHS rhs, typename LHS>
-bool less_than_impl(
- typename std::enable_if<
- (rhs <= std::numeric_limits<LHS>::min()),
- LHS
- >::type const
-) {
- return false;
+bool greater_than_impl(LHS const lhs) {
+ return
+ rhs > std::numeric_limits<LHS>::max() ? false :
+ rhs < std::numeric_limits<LHS>::min() ? true :
+ lhs > rhs;
}
-template <typename RHS, RHS rhs, typename LHS>
-bool greater_than_impl(
- typename std::enable_if<
- (rhs <= std::numeric_limits<LHS>::max()
- && rhs >= std::numeric_limits<LHS>::min()),
- LHS
- >::type const lhs
-) {
- return lhs > rhs;
-}
-
-template <typename RHS, RHS rhs, typename LHS>
-bool greater_than_impl(
- typename std::enable_if<
- (rhs > std::numeric_limits<LHS>::max()),
- LHS
- >::type const
-) {
- return false;
-}
-
-template <typename RHS, RHS rhs, typename LHS>
-bool greater_than_impl(
- typename std::enable_if<
- (rhs < std::numeric_limits<LHS>::min()),
- LHS
- >::type const
-) {
- return true;
-}
+#pragma GCC diagnostic pop
} // namespace detail {
template <typename T>
constexpr bool is_non_positive(T x) { return !x || folly::is_negative(x); }
+// same as `x > 0`
+template <typename T>
+constexpr bool is_positive(T x) { return !is_non_positive(x); }
+
+// same as `x >= 0`
+template <typename T>
+constexpr bool is_non_negative(T x) {
+ return !x || is_positive(x);
+}
+
template <typename RHS, RHS rhs, typename LHS>
bool less_than(LHS const lhs) {
return detail::less_than_impl<
>(lhs);
}
+/**
+ * Like std::piecewise_construct, a tag type & instance used for in-place
+ * construction of non-movable contained types, e.g. by Synchronized.
+ */
+struct construct_in_place_t {};
+constexpr construct_in_place_t construct_in_place{};
+
+/**
+ * Initializer lists are a powerful compile time syntax introduced in C++11
+ * but due to their often conflicting syntax they are not used by APIs for
+ * construction.
+ *
+ * Further standard conforming compilers *strongly* favor an
+ * std::initalizer_list overload for construction if one exists. The
+ * following is a simple tag used to disambiguate construction with
+ * initializer lists and regular uniform initialization.
+ *
+ * For example consider the following case
+ *
+ * class Something {
+ * public:
+ * explicit Something(int);
+ * Something(std::intiializer_list<int>);
+ *
+ * operator int();
+ * };
+ *
+ * ...
+ * Something something{1}; // SURPRISE!!
+ *
+ * The last call to instantiate the Something object will go to the
+ * initializer_list overload. Which may be surprising to users.
+ *
+ * If however this tag was used to disambiguate such construction it would be
+ * easy for users to see which construction overload their code was referring
+ * to. For example
+ *
+ * class Something {
+ * public:
+ * explicit Something(int);
+ * Something(folly::initlist_construct_t, std::initializer_list<int>);
+ *
+ * operator int();
+ * };
+ *
+ * ...
+ * Something something_one{1}; // not the initializer_list overload
+ * Something something_two{folly::initlist_construct, {1}}; // correct
+ */
+struct initlist_construct_t {};
+constexpr initlist_construct_t initlist_construct{};
+
} // namespace folly
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(std::basic_string);
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::vector);
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::list);
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::deque);
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::unique_ptr);
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::shared_ptr);
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::function);
+// gcc-5.0 changed string's implementation in libgcc to be non-relocatable
+#if __GNUC__ < 5
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(std::basic_string)
+#endif
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::vector)
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::list)
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::deque)
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::unique_ptr)
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::shared_ptr)
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::function)
// Boost
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(boost::shared_ptr);
+FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(boost::shared_ptr)
+
+#define FOLLY_CREATE_HAS_MEMBER_TYPE_TRAITS(classname, type_name) \
+ template <typename T> \
+ struct classname { \
+ template <typename C> \
+ constexpr static bool test(typename C::type_name*) { return true; } \
+ template <typename> \
+ constexpr static bool test(...) { return false; } \
+ constexpr static bool value = test<T>(nullptr); \
+ }
#define FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, cv_qual) \
template <typename TTheClass_, typename RTheReturn_, typename... TTheArgs_> \
template <typename, typename> class classname; \
FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, ); \
FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, const); \
- FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, volatile); \
- FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, volatile const)
-
-#endif //FOLLY_BASE_TRAITS_H_
+ FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL( \
+ classname, func_name, /* nolint */ volatile); \
+ FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL( \
+ classname, func_name, /* nolint */ volatile const)
projects / folly.git / blobdiff