Fix reliance on the sign of char in fnv32 and fnv64

[folly.git] / folly / Optional.h

diff --git a/folly/Optional.h b/folly/Optional.h
index 61e71c1f2dc86b3709d1e265b9e72b50c8a487ba..16cf86a10090d75575749c34fbad902f4c47d83f 100644 (file)
--- a/folly/Optional.h
+++ b/folly/Optional.h
@@ -54,6 +54,7 @@
  *  }
  */
 #include <cstddef>
+#include <functional>
 #include <new>
 #include <stdexcept>
 #include <type_traits>
@@ -63,7 +64,14 @@
 
 namespace folly {
 
-namespace detail { struct NoneHelper {}; }
+namespace detail {
+struct NoneHelper {};
+
+// Allow each translation unit to control its own -fexceptions setting.
+// If exceptions are disabled, std::terminate() will be called instead of
+// throwing OptionalEmptyException when the condition fails.
+[[noreturn]] void throw_optional_empty_exception();
+}
 
 typedef int detail::NoneHelper::*None;
 
@@ -251,7 +259,7 @@ class Optional {
  private:
   void require_value() const {
     if (!storage_.hasValue) {
-      throw OptionalEmptyException();
+      detail::throw_optional_empty_exception();
     }
   }
 
@@ -351,57 +359,57 @@ Opt make_optional(T&& v) {
 ///////////////////////////////////////////////////////////////////////////////
 // Comparisons.
 
-template<class V>
-bool operator==(const Optional<V>& a, const V& b) {
+template <class U, class V>
+bool operator==(const Optional<U>& a, const V& b) {
   return a.hasValue() && a.value() == b;
 }
 
-template<class V>
-bool operator!=(const Optional<V>& a, const V& b) {
+template <class U, class V>
+bool operator!=(const Optional<U>& a, const V& b) {
   return !(a == b);
 }
 
-template<class V>
-bool operator==(const V& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator==(const U& a, const Optional<V>& b) {
   return b.hasValue() && b.value() == a;
 }
 
-template<class V>
-bool operator!=(const V& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator!=(const U& a, const Optional<V>& b) {
   return !(a == b);
 }
 
-template<class V>
-bool operator==(const Optional<V>& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator==(const Optional<U>& a, const Optional<V>& b) {
   if (a.hasValue() != b.hasValue()) { return false; }
   if (a.hasValue())                 { return a.value() == b.value(); }
   return true;
 }
 
-template<class V>
-bool operator!=(const Optional<V>& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator!=(const Optional<U>& a, const Optional<V>& b) {
   return !(a == b);
 }
 
-template<class V>
-bool operator< (const Optional<V>& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator<(const Optional<U>& a, const Optional<V>& b) {
   if (a.hasValue() != b.hasValue()) { return a.hasValue() < b.hasValue(); }
   if (a.hasValue())                 { return a.value()    < b.value(); }
   return false;
 }
 
-template<class V>
-bool operator> (const Optional<V>& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator>(const Optional<U>& a, const Optional<V>& b) {
   return b < a;
 }
 
-template<class V>
-bool operator<=(const Optional<V>& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator<=(const Optional<U>& a, const Optional<V>& b) {
   return !(b < a);
 }
 
-template<class V>
-bool operator>=(const Optional<V>& a, const Optional<V>& b) {
+template <class U, class V>
+bool operator>=(const Optional<U>& a, const Optional<V>& b) {
   return !(a < b);
 }
 
@@ -418,3 +426,16 @@ template<class V> bool operator> (const V& other, const Optional<V>&) = delete;
 ///////////////////////////////////////////////////////////////////////////////
 
 } // namespace folly
+
+// Allow usage of Optional<T> in std::unordered_map and std::unordered_set
+FOLLY_NAMESPACE_STD_BEGIN
+template <class T>
+struct hash<folly::Optional<T>> {
+  size_t operator()(folly::Optional<T> const& obj) const {
+    if (!obj.hasValue()) {
+      return 0;
+    }
+    return hash<typename remove_const<T>::type>()(*obj);
+  }
+};
+FOLLY_NAMESPACE_STD_END