Drop the boost dependency from Traits.h and FBVector.h

Summary:
[Folly] Drop the `boost` dependency from `Traits.h` and `FBVector.h`.

Should not need it anymore with the currently supported compilers.

Reviewed By: ericniebler

Differential Revision: D4375572

fbshipit-source-id: df890c07f49b0499d2d2d08aa21c226b2893281e

folly/FBVector.h

@@ -210,7 +210,7 @@ class fbvector {
 private:
 
   typedef std::integral_constant<bool,
-      boost::has_trivial_copy_constructor<T>::value &&
+      IsTriviallyCopyable<T>::value &&
       sizeof(T) <= 16 // don't force large structures to be passed by value
     > should_pass_by_value;
   typedef typename std::conditional<
@@ -322,7 +322,8 @@ class fbvector {
 
   void M_destroy(T* p) noexcept {
     if (usingStdAllocator::value) {
-      if (!boost::has_trivial_destructor<T>::value) p->~T();
+      if (!std::is_trivially_destructible<T>::value)
+        p->~T();
     } else {
       std::allocator_traits<Allocator>::destroy(impl_, p);
     }
@@ -360,7 +361,7 @@ class fbvector {
 
   // optimized
   static void S_destroy_range(T* first, T* last) noexcept {
-    if (!boost::has_trivial_destructor<T>::value) {
+    if (!std::is_trivially_destructible<T>::value) {
       // EXPERIMENTAL DATA on fbvector<vector<int>> (where each vector<int> has
       //  size 0).
       // The unrolled version seems to work faster for small to medium sized

folly/MPMCQueue.h

@@ -86,7 +86,7 @@ template <typename> class MPMCQueueBase;
 /// use noexcept, you will have to wrap it in something that provides
 /// the guarantee.  We provide an alternate safe implementation for types
 /// that don't use noexcept but that are marked folly::IsRelocatable
-/// and boost::has_nothrow_constructor, which is common for folly types.
+/// and std::is_nothrow_constructible, which is common for folly types.
 /// In particular, if you can declare FOLLY_ASSUME_FBVECTOR_COMPATIBLE
 /// then your type can be put in MPMCQueue.
 ///
@@ -1310,15 +1310,17 @@ struct SingleElementQueue {
 
   /// enqueue using move construction, either real (if
   /// is_nothrow_move_constructible) or simulated using relocation and
-  /// default construction (if IsRelocatable and has_nothrow_constructor)
-  template <typename = typename std::enable_if<
-                (folly::IsRelocatable<T>::value &&
-                 boost::has_nothrow_constructor<T>::value) ||
-                std::is_nothrow_constructible<T, T&&>::value>::type>
-  void enqueue(const uint32_t turn,
-               Atom<uint32_t>& spinCutoff,
-               const bool updateSpinCutoff,
-               T&& goner) noexcept {
+  /// default construction (if IsRelocatable and is_nothrow_constructible)
+  template <
+      typename = typename std::enable_if<
+          (folly::IsRelocatable<T>::value &&
+           std::is_nothrow_constructible<T>::value) ||
+          std::is_nothrow_constructible<T, T&&>::value>::type>
+  void enqueue(
+      const uint32_t turn,
+      Atom<uint32_t>& spinCutoff,
+      const bool updateSpinCutoff,
+      T&& goner) noexcept {
     enqueueImpl(
         turn,
         spinCutoff,

folly/Makefile.am

@@ -8,7 +8,6 @@ ACLOCAL_AMFLAGS = -I m4
 
 CLEANFILES =
 
-
 noinst_PROGRAMS = generate_fingerprint_tables
 generate_fingerprint_tables_SOURCES = build/GenerateFingerprintTables.cpp
 generate_fingerprint_tables_LDADD = libfollybase.la

folly/String.h

@@ -646,12 +646,4 @@ using UTF8StringPiece = UTF8Range<const char*>;
 
 } // namespace folly
 
-// Hook into boost's type traits
-namespace boost {
-template <class T>
-struct has_nothrow_constructor<folly::basic_fbstring<T> > : true_type {
-  enum { value = true };
-};
-} // namespace boost
-
 #include <folly/String-inl.h>

folly/Traits.h

@@ -36,8 +36,6 @@
 #include <bits/c++config.h>
 #endif
 
-#include <boost/type_traits.hpp>
-
 #define FOLLY_CREATE_HAS_MEMBER_TYPE_TRAITS(classname, type_name)              \
   template <typename TTheClass_>                                               \
   struct classname##__folly_traits_impl__ {                                    \
@@ -341,29 +339,12 @@ using StrictConjunction =
   struct IsRelocatable<  __VA_ARGS__ > : std::true_type {};
 
 /**
- * Use this macro ONLY inside namespace boost. When using it with a
- * regular type, use it like this:
- *
- * // Make sure you're at namespace ::boost scope
- * template<> FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(MyType)
- *
- * When using it with a template type, use it like this:
- *
- * // Make sure you're at namespace ::boost scope
- * template<class T1, class T2>
- * FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(MyType<T1, T2>)
- */
-#define FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(...) \
-  struct has_nothrow_constructor<  __VA_ARGS__ > : ::boost::true_type {};
-
-/**
- * The FOLLY_ASSUME_FBVECTOR_COMPATIBLE* macros below encode two
- * assumptions: first, that the type is relocatable per IsRelocatable
- * above, and that it has a nothrow constructor. Most types can be
- * assumed to satisfy both conditions, but it is the responsibility of
- * the user to state that assumption. User-defined classes will not
- * work with fbvector (see FBVector.h) unless they state this
- * combination of properties.
+ * The FOLLY_ASSUME_FBVECTOR_COMPATIBLE* macros below encode the
+ * assumption that the type is relocatable per IsRelocatable
+ * above. Many types can be assumed to satisfy this condition, but
+ * it is the responsibility of the user to state that assumption.
+ * User-defined classes will not be optimized for use with
+ * fbvector (see FBVector.h) unless they state that assumption.
  *
  * Use FOLLY_ASSUME_FBVECTOR_COMPATIBLE with regular types like this:
  *
@@ -382,40 +363,35 @@ using StrictConjunction =
  */
 
 // Use this macro ONLY at global level (no namespace)
-#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE(...)                           \
-  namespace folly { template<> FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__) }   \
-  namespace boost { \
-  template<> FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(__VA_ARGS__) }
+#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE(...) \
+  namespace folly {                           \
+  template <>                                 \
+  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__)       \
+  }
 // Use this macro ONLY at global level (no namespace)
-#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(...)                         \
-  namespace folly {                                                     \
-  template <class T1> FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1>) }       \
-    namespace boost {                                                   \
-    template <class T1> FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(__VA_ARGS__<T1>) }
+#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(...) \
+  namespace folly {                             \
+  template <class T1>                           \
+  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1>)     \
+  }
 // Use this macro ONLY at global level (no namespace)
-#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(...)                 \
-  namespace folly {                                             \
-  template <class T1, class T2>                                 \
-  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2>) }               \
-    namespace boost {                                           \
-    template <class T1, class T2>                               \
-    FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(__VA_ARGS__<T1, T2>) }
+#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(...) \
+  namespace folly {                             \
+  template <class T1, class T2>                 \
+  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2>) \
+  }
 // Use this macro ONLY at global level (no namespace)
-#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(...)                         \
-  namespace folly {                                                     \
-  template <class T1, class T2, class T3>                               \
-  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3>) }                   \
-    namespace boost {                                                   \
-    template <class T1, class T2, class T3>                             \
-    FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(__VA_ARGS__<T1, T2, T3>) }
+#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(...)     \
+  namespace folly {                                 \
+  template <class T1, class T2, class T3>           \
+  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3>) \
+  }
 // Use this macro ONLY at global level (no namespace)
-#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_4(...)                         \
-  namespace folly {                                                     \
-  template <class T1, class T2, class T3, class T4>                     \
-  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3, T4>) }               \
-    namespace boost {                                                   \
-    template <class T1, class T2, class T3, class T4>                   \
-    FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(__VA_ARGS__<T1, T2, T3, T4>) }
+#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_4(...)         \
+  namespace folly {                                     \
+  template <class T1, class T2, class T3, class T4>     \
+  FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3, T4>) \
+  }
 
 /**
  * Instantiate FOLLY_ASSUME_FBVECTOR_COMPATIBLE for a few types. It is
@@ -454,18 +430,6 @@ template <class T>
 
 FOLLY_NAMESPACE_STD_END
 
-namespace boost {
-
-template <class T> class shared_ptr;
-
-template <class T, class U>
-struct has_nothrow_constructor< std::pair<T, U> >
-    : std::integral_constant<bool,
-        has_nothrow_constructor<T>::value &&
-        has_nothrow_constructor<U>::value> {};
-
-} // namespace boost
-
 namespace folly {
 
 // STL commonly-used types
@@ -681,9 +645,6 @@ 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)
 #endif
 
 /* Some combinations of compilers and C++ libraries make __int128 and

folly/docs/FBVector.md

@@ -189,33 +189,6 @@ after `Widget`'s definition and write this:
 If you don't do this, `fbvector<Widget>` will fail to compile
 with a `static_assert`.
 
-#### Additional Constraints
-
-Similar improvements are possible in presence of a "simple" type
-- more specifically, one that has a trivial assignment (i.e.
-assignment is the same as bitblitting the bits over) or a nothrow
-default constructor. These traits are used gainfully by
-`fbvector` in a variety of places. Fortunately, these traits are
-already present in the C++ standard (well, currently in Boost).
-To summarize, in order to work with `fbvector`, a type `Widget`
-must pass:
-
-    static_assert(
-      IsRelocatable<Widget>::value &&
-      (boost::has_trivial_assign<T>::value ||
-       boost::has_nothrow_constructor<T>::value),
-      "");
-
-These traits go hand in hand; for example, it would be very
-difficult to design a class that satisfies one branch of the
-conjunction above but not the other. `fbvector` uses these simple
-constraints to minimize the number of copies made on many common
-operations such as `push_back`, `insert`, or `resize`.
-
-To make it easy for you to state assumptions about a given type
-or family of parameterized types, check Traits.h and in
-particular handy family of macros FOLLY_ASSUME_FBVECTOR_COMPATIBLE*.
-
 ### Miscellaneous
 ***
 

folly/docs/Traits.md

@@ -1,7 +1,7 @@
 'folly/Traits.h'
 -----------------
 
-Implements traits complementary to those provided in <boost/type_traits.h>
+Implements traits complementary to those provided in <type_traits>
 
   * Implements `IsRelocatable` trait.
   * Implements `IsOneOf` trait
@@ -10,12 +10,11 @@ Implements traits complementary to those provided in <boost/type_traits.h>
 ### Motivation
 ***
 
-`<boost/type_traits.hpp>` is the Boost type-traits library defining a 
-variety of traits such as `is_integral` or `is_floating_point`. This helps 
-to gain more information about a given type.
-Many traits introduced by Boost have been standardized in C++11.
+`<type_traits>` is the Standard type-traits library defining a variety of traits
+such as `is_integral` or `is_floating_point`. This helps to gain more
+information about a given type.
 
-`folly/Traits.h` implements traits complementing those present in boost. 
+`folly/Traits.h` implements traits complementing those present in the Standard.
 
 
 ### IsRelocatable
@@ -88,11 +87,11 @@ a value of type T by using memcpy.
     namespace folly {
       // defining specialization of IsRelocatable for MySimpleType
       template <>
-      struct IsRelocatable<MySimpleType> : boost::true_type {};
+      struct IsRelocatable<MySimpleType> : std::true_type {};
       // defining specialization of IsRelocatable for MyParameterizedType
       template <class T1, class T2>
       struct IsRelocatable<MyParameterizedType<T1, T2>>
-          : ::boost::true_type {};
+          : ::std::true_type {};
     }
     ```
 
@@ -111,17 +110,6 @@ a value of type T by using memcpy.
     }
     ```
 
-  * Stating that a type has no throw constructor using a macro
-
-    ```Cpp
-    namespace boost {
-      // For a Regular Type
-      FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(MySimpleType);
-      // For a Parameterized Type
-      FOLLY_ASSUME_HAS_NOTHROW_CONSTRUCTOR(MyParameterizedType<T1, T2>);
-    }
-    ```
-
 `fbvector` only works with relocatable objects. If assumptions are not stated 
 explicitly, `fbvector<MySimpleType>` or `fbvector<MyParameterizedType>` 
 will fail to compile due to assertion below:
@@ -157,17 +145,17 @@ Similarly,
 
 Few common types, namely `std::basic_string`, `std::vector`, `std::list`,
 `std::map`, `std::deque`, `std::set`, `std::unique_ptr`, `std::shared_ptr`,
-`std::function`, `boost::shared_ptr` which are compatible with `fbvector` are
-already instantiated and declared compatible with `fbvector`. `fbvector` can be
-directly used with any of these C++ types.
+`std::function`, which are compatible with `fbvector` are already instantiated
+and declared compatible with `fbvector`. `fbvector` can be directly used with
+any of these C++ types.
 
 `std::pair` can be safely assumed to be compatible with `fbvector` if both of
 its components are.
 
 ### IsOneOf
 ***
 
-`boost::is_same<T1, T2>::value` can be used to test if types of T1 and T2 are 
-same. `folly::IsOneOf<T, T1, Ts...>::value` can be used to test if type of T1 
+`std::is_same<T1, T2>::value` can be used to test if types of T1 and T2 are
+same. `folly::IsOneOf<T, T1, Ts...>::value` can be used to test if type of T1
 matches the type of one of the other template parameter, T1, T2, ...Tn.
 Recursion is used to implement this type trait.