X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FTraits.h;h=2b94df1360effe21828adedb51b864e7d2282116;hb=fd915b73606e09a5f46a1bca0a5d3643a1567014;hp=bc0a0bf68847f1270b389eb9a87d5a6b3ce2088e;hpb=1bf1654c689b31ac7b53f499b8f1810548fbda7a;p=folly.git

diff --git a/folly/Traits.h b/folly/Traits.h
index bc0a0bf6..2b94df13 100644
--- 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.
@@ -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>
@@ -222,7 +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;
@@ -246,7 +259,7 @@ template <class K, class V, class C, class A>
 template <class T>
   class shared_ptr;
 
-}
+FOLLY_NAMESPACE_STD_END
 
 namespace boost {
 
@@ -277,10 +290,42 @@ 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 to check for a negative/non-positive value.
+ * Complementary type traits for integral comparisons.
+ *
+ * For instance, `if(x < 0)` yields an error in clang for unsigned types
+ *  when -Werror is used due to -Wtautological-compare
  *
- * `if(x < 0)` yields an error in clang for unsigned types when -Werror is used
+ *
+ * @author: Marcelo Juchem <marcelo@fb.com>
  */
 
 namespace detail {
@@ -295,6 +340,68 @@ struct is_negative_impl<T, false> {
   constexpr static bool check(T x) { return false; }
 };
 
+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()),
+    LHS
+  >::type const lhs
+) {
+  return lhs < rhs;
+}
+
+template <typename RHS, RHS rhs, typename LHS>
+bool less_than_impl(
+  typename std::enable_if<
+    (rhs > std::numeric_limits<LHS>::max()),
+    LHS
+  >::type const
+) {
+  return true;
+}
+
+template <typename RHS, RHS rhs, typename LHS>
+bool less_than_impl(
+  typename std::enable_if<
+    (rhs <= std::numeric_limits<LHS>::min()),
+    LHS
+  >::type const
+) {
+  return false;
+}
+
+template <typename RHS, RHS rhs, typename LHS>
+bool greater_than_impl(
+  typename std::enable_if<
+    (rhs <= std::numeric_limits<LHS>::max()
+      && rhs >= std::numeric_limits<LHS>::min()),
+    LHS
+  >::type const lhs
+) {
+  return lhs > rhs;
+}
+
+template <typename RHS, RHS rhs, typename LHS>
+bool greater_than_impl(
+  typename std::enable_if<
+    (rhs > std::numeric_limits<LHS>::max()),
+    LHS
+  >::type const
+) {
+  return false;
+}
+
+template <typename RHS, RHS rhs, typename LHS>
+bool greater_than_impl(
+  typename std::enable_if<
+    (rhs < std::numeric_limits<LHS>::min()),
+    LHS
+  >::type const
+) {
+  return true;
+}
+
 } // namespace detail {
 
 // same as `x < 0`
@@ -307,14 +414,36 @@ 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);
+}
+
 } // 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);
@@ -382,6 +511,8 @@ 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; \