Harden failure signal handler in the face of memory corruptions

[folly.git] / folly / Traits.h

diff --git a/folly/Traits.h b/folly/Traits.h
index f09a9136cab7a2a82f1bb59d1c8bb5703cb9c75b..966dcc578f7355e33cf8e8477c86f70dc67a3d24 100644 (file)
--- a/folly/Traits.h
+++ b/folly/Traits.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2014 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,7 +23,18 @@
 #include <limits>
 #include <type_traits>
 
+#include "folly/Portability.h"
+
+// libc++ doesn't provide this header
+#if !FOLLY_USE_LIBCPP
+// 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 +234,7 @@ 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 +258,7 @@ template <class K, class V, class C, class A>
 template <class T>
   class shared_ptr;
 
-}
+FOLLY_NAMESPACE_STD_END
 
 namespace boost {
 
@@ -332,7 +343,7 @@ 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()),
+      && rhs > std::numeric_limits<LHS>::min()),
     LHS
   >::type const lhs
 ) {
@@ -352,7 +363,7 @@ bool less_than_impl(
 template <typename RHS, RHS rhs, typename LHS>
 bool less_than_impl(
   typename std::enable_if<
-    (rhs < std::numeric_limits<LHS>::min()),
+    (rhs <= std::numeric_limits<LHS>::min()),
     LHS
   >::type const
 ) {
@@ -402,6 +413,16 @@ 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<
@@ -422,8 +443,6 @@ 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);