fix Baton.h typo

[folly.git] / folly / Traits.h

diff --git a/folly/Traits.h b/folly/Traits.h
index 37bd58d389f4114b079be3324a95d1303c2633aa..309157c4dfadcf952faddc8284bf004f07a401ac 100644 (file)
--- 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.
@@ -22,8 +22,20 @@
 #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>
@@ -223,7 +235,7 @@ 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;
@@ -247,7 +259,7 @@ template <class K, class V, class C, class A>
 template <class T>
   class shared_ptr;
 
-}
+FOLLY_NAMESPACE_STD_END
 
 namespace boost {
 
@@ -278,34 +290,6 @@ 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
- *
- *  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.
  *
@@ -328,6 +312,13 @@ struct is_negative_impl<T, false> {
   constexpr static bool check(T x) { 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(
   typename std::enable_if<
@@ -359,6 +350,8 @@ bool less_than_impl(
   return false;
 }
 
+#pragma GCC diagnostic pop
+
 template <typename RHS, RHS rhs, typename LHS>
 bool greater_than_impl(
   typename std::enable_if<
@@ -402,6 +395,16 @@ 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<
@@ -496,7 +499,9 @@ FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(boost::shared_ptr);
   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_