lift Default{Hasher, KeyEqual, Alloc} out of detail namespace

Summary:
Expose the default structs in `folly::f14` namespace so that users _could_
potentially refer to them.

Reviewed By: nbronson

Differential Revision: D7271846

fbshipit-source-id: 81a193209e59ed80260098ed97c99a7b6f2ad151

folly/container/F14Map.h

@@ -723,9 +723,9 @@ bool mapsEqual(M const& lhs, M const& rhs) {
 template <
     typename Key,
     typename Mapped,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<std::pair<Key const, Mapped>>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<std::pair<Key const, Mapped>>>
 class F14ValueMap
     : public f14::detail::F14BasicMap<f14::detail::MapPolicyWithDefaults<
           f14::detail::ValueContainerPolicy,
@@ -780,9 +780,9 @@ bool operator!=(
 template <
     typename Key,
     typename Mapped,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<std::pair<Key const, Mapped>>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<std::pair<Key const, Mapped>>>
 class F14NodeMap
     : public f14::detail::F14BasicMap<f14::detail::MapPolicyWithDefaults<
           f14::detail::NodeContainerPolicy,
@@ -839,9 +839,9 @@ bool operator!=(
 template <
     typename Key,
     typename Mapped,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<std::pair<Key const, Mapped>>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<std::pair<Key const, Mapped>>>
 class F14VectorMap
     : public f14::detail::F14BasicMap<f14::detail::MapPolicyWithDefaults<
           f14::detail::VectorContainerPolicy,
@@ -976,9 +976,9 @@ bool operator!=(
 template <
     typename Key,
     typename Mapped,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<std::pair<Key const, Mapped>>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<std::pair<Key const, Mapped>>>
 using F14FastMap = std::conditional_t<
     sizeof(std::pair<Key const, Mapped>) < 24,
     F14ValueMap<Key, Mapped, Hasher, KeyEqual, Alloc>,

folly/container/F14Set.h

@@ -506,9 +506,9 @@ bool setsEqual(S const& lhs, S const& rhs) {
 
 template <
     typename Key,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<Key>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<Key>>
 class F14ValueSet
     : public f14::detail::F14BasicSet<f14::detail::SetPolicyWithDefaults<
           f14::detail::ValueContainerPolicy,
@@ -559,9 +559,9 @@ bool operator!=(
 
 template <
     typename Key,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<Key>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<Key>>
 class F14NodeSet
     : public f14::detail::F14BasicSet<f14::detail::SetPolicyWithDefaults<
           f14::detail::NodeContainerPolicy,
@@ -612,9 +612,9 @@ bool operator!=(
 
 template <
     typename Key,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<Key>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<Key>>
 class F14VectorSet
     : public f14::detail::F14BasicSet<f14::detail::SetPolicyWithDefaults<
           f14::detail::VectorContainerPolicy,
@@ -741,9 +741,9 @@ bool operator!=(
 
 template <
     typename Key,
-    typename Hasher = f14::detail::DefaultHasher<Key>,
-    typename KeyEqual = f14::detail::DefaultKeyEqual<Key>,
-    typename Alloc = f14::detail::DefaultAlloc<Key>>
+    typename Hasher = f14::DefaultHasher<Key>,
+    typename KeyEqual = f14::DefaultKeyEqual<Key>,
+    typename Alloc = f14::DefaultAlloc<Key>>
 using F14FastSet = std::conditional_t<
     sizeof(Key) < 24,
     F14ValueSet<Key, Hasher, KeyEqual, Alloc>,

folly/container/detail/F14Table.h

@@ -125,8 +125,28 @@ class F14HashToken final {
 };
 
 namespace f14 {
+
+template <typename T>
+using DefaultHasher = std::hash<T>;
+
+template <typename T>
+using DefaultKeyEqual = std::equal_to<T>;
+
+template <typename T>
+using DefaultAlloc = std::allocator<T>;
+
 namespace detail {
 
+//// Defaults should be selected using void
+
+template <typename Arg, typename Default>
+using VoidDefault =
+    std::conditional_t<std::is_same<Arg, Default>::value, void, Arg>;
+
+template <typename Arg, typename Default>
+using Defaulted =
+    typename std::conditional_t<std::is_same<Arg, void>::value, Default, Arg>;
+
 template <
     typename Void,
     typename Hasher,
@@ -147,25 +167,6 @@ struct EnableIfIsTransparent<
   using type = T;
 };
 
-//// Defaults should be selected using void
-
-template <typename Arg, typename Default>
-using VoidDefault =
-    std::conditional_t<std::is_same<Arg, Default>::value, void, Arg>;
-
-template <typename Arg, typename Default>
-using Defaulted =
-    typename std::conditional_t<std::is_same<Arg, void>::value, Default, Arg>;
-
-template <typename T>
-using DefaultHasher = std::hash<T>;
-
-template <typename T>
-using DefaultKeyEqual = std::equal_to<T>;
-
-template <typename T>
-using DefaultAlloc = std::allocator<T>;
-
 ////////////////
 
 template <typename T>