X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FTraits.h;h=16aab8d6ef1e9011b195e44f35d04e69b00144cc;hb=422c78beb630d6d5518ba357d3f8ae7d792d6415;hp=ebdb84d1e28ac0ac2856fac14bdb3da18391795e;hpb=622fe822372560c525bd8029d6e68d06d81d24d6;p=folly.git

diff --git a/folly/Traits.h b/folly/Traits.h
index ebdb84d1..16aab8d6 100644
--- a/folly/Traits.h
+++ b/folly/Traits.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2015 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,9 +20,22 @@
 #define FOLLY_BASE_TRAITS_H_
 
 #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>
@@ -222,13 +235,15 @@ template <class T> struct IsZeroInitializable
  * 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;
@@ -237,8 +252,10 @@ template <class T, class A>
   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>
@@ -246,7 +263,7 @@ template <class K, class V, class C, class A>
 template <class T>
   class shared_ptr;
 
-}
+FOLLY_NAMESPACE_STD_END
 
 namespace boost {
 
@@ -277,39 +294,15 @@ struct IsOneOf<T, T1, 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
+/*
+ * Complementary type traits for integral comparisons.
  *
- *  struct ForwardDeclared {}; // declared, at last
+ * For instance, `if(x < 0)` yields an error in clang for unsigned types
+ *  when -Werror is used due to -Wtautological-compare
  *
- *  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 to check for a negative/non-positive value.
- *
- * `if(x < 0)` yields an error in clang for unsigned types when -Werror is used
- */
 
 namespace detail {
 
@@ -320,9 +313,34 @@ struct is_negative_impl {
 
 template <typename T>
 struct is_negative_impl<T, false> {
-  constexpr static bool check(T x) { return false; }
+  constexpr static bool check(T) { return false; }
 };
 
+// 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 so suppress them in order to not prevent
+// all calling code from using it.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsign-compare"
+
+template <typename RHS, RHS rhs, typename LHS>
+bool less_than_impl(LHS const lhs) {
+  return
+    rhs > std::numeric_limits<LHS>::max() ? true :
+    rhs <= std::numeric_limits<LHS>::min() ? false :
+    lhs < rhs;
+}
+
+#pragma GCC diagnostic pop
+
+template <typename RHS, RHS rhs, typename LHS>
+bool greater_than_impl(LHS const lhs) {
+  return
+    rhs > std::numeric_limits<LHS>::max() ? false :
+    rhs < std::numeric_limits<LHS>::min() ? true :
+    lhs > rhs;
+}
+
 } // namespace detail {
 
 // same as `x < 0`
@@ -335,14 +353,43 @@ constexpr bool is_negative(T x) {
 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<
+    RHS, rhs, typename std::remove_reference<LHS>::type
+  >(lhs);
+}
+
+template <typename RHS, RHS rhs, typename LHS>
+bool greater_than(LHS const lhs) {
+  return detail::greater_than_impl<
+    RHS, rhs, typename std::remove_reference<LHS>::type
+  >(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{};
+
 } // 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_4(std::map);
-FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(std::set);
 FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::unique_ptr);
 FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::shared_ptr);
 FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::function);
@@ -350,6 +397,16 @@ FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::function);
 // Boost
 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_> \
   class classname<TTheClass_, RTheReturn_(TTheArgs_...) cv_qual> { \
@@ -410,12 +467,16 @@ FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(boost::shared_ptr);
  *   cout << "Does class Bar have a member double test(const string&, long)? "
  *     << boolalpha << has_test_traits<Bar, double(const string&, long)>::value;
  * }
+ *
+ * @author: Marcelo Juchem <marcelo@fb.com>
  */
 #define FOLLY_CREATE_HAS_MEMBER_FN_TRAITS(classname, func_name) \
   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)
+  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)
 
 #endif //FOLLY_BASE_TRAITS_H_