Make ModifiedConditions Nullable. (#1761)

* Make ModifiedConditions Nullable.
Add access helpers for Nullable.

sdk/core/azure-core/inc/azure/core/modified_conditions.hpp

@@ -9,6 +9,7 @@
 #pragma once
 
 #include "azure/core/datetime.hpp"
+#include "azure/core/nullable.hpp"
 
 #include <string>
 
@@ -23,11 +24,11 @@ namespace Azure { namespace Core {
      * @brief Optionally limit requests to resources that have only been modified since this point
      * in time.
      */
-    Azure::Core::DateTime IfModifiedSince;
+    Azure::Core::Nullable<Azure::Core::DateTime> IfModifiedSince;
 
     /**
      * @brief Optionally limit requests to resources that have remained unmodified.
      */
-    Azure::Core::DateTime IfUnmodifiedSince;
+    Azure::Core::Nullable<Azure::Core::DateTime> IfUnmodifiedSince;
   };
 }} // namespace Azure::Core

sdk/core/azure-core/inc/azure/core/nullable.hpp

@@ -261,10 +261,72 @@ namespace Azure { namespace Core {
       return std::move(m_value);
     }
 
+    // observers
+
     /**
      * @brief `operator bool` on the condition of #Azure::Core::Nullable::HasValue.
      */
-    explicit operator bool() const noexcept { return HasValue(); }
+    constexpr explicit operator bool() const noexcept { return HasValue(); }
+
+    /**
+     * @brief Accesses the contained value.
+     * @return Returns a pointer to the contained value.
+     * @warning The behavior is undefined if `*this` does not contain a value.
+     * @note This operator does not check whether the #Nullable contains a value!
+             You can do so manually by using #HasValue() or simply operator #bool().
+             Alternatively, if checked access is needed, #GetValue() or #ValueOr() may be used.
+     */
+    constexpr const T* operator->() const { return std::addressof(m_value); }
+
+    /**
+     * @brief Accesses the contained value.
+     * @return Returns a pointer to the contained value.
+     * @warning The behavior is undefined if `*this` does not contain a value.
+     * @note This operator does not check whether the #Nullable contains a value!
+             You can do so manually by using #HasValue() or simply operator #bool().
+             Alternatively, if checked access is needed, #GetValue() or #ValueOr() may be used.
+     */
+    constexpr T* operator->() { return std::addressof(m_value); }
+
+    /**
+     * @brief Accesses the contained value.
+     * @return Returns a reference to the contained value.
+     * @warning The behavior is undefined if `*this` does not contain a value.
+     * @note This operator does not check whether the #Nullable contains a value!
+             You can do so manually by using #HasValue() or simply operator #bool().
+             Alternatively, if checked access is needed, #GetValue() or #ValueOr() may be used.
+     */
+    constexpr const T& operator*() const& { return m_value; }
+
+    /**
+     * @brief Accesses the contained value.
+     * @return Returns a reference to the contained value.
+     * @warning The behavior is undefined if `*this` does not contain a value.
+     * @note This operator does not check whether the #Nullable contains a value!
+             You can do so manually by using #HasValue() or simply operator #bool().
+             Alternatively, if checked access is needed, #GetValue() or #ValueOr() may be used.
+     */
+    constexpr T& operator*() & { return m_value; }
+
+    /**
+     * @brief Accesses the contained value.
+     * @return Returns a reference to the contained value.
+     * @warning The behavior is undefined if `*this` does not contain a value.
+     * @note This operator does not check whether the #Nullable contains a value!
+             You can do so manually by using #HasValue() or simply operator #bool().
+             Alternatively, if checked access is needed, #GetValue() or #ValueOr() may be used.
+     */
+    constexpr T&& operator*() && { return std::move(m_value); }
+
+    /**
+     * @brief Accesses the contained value.
+     * @return Returns a reference to the contained value.
+     * @warning The behavior is undefined if `*this` does not contain a value.
+     * @note This operator does not check whether the #Nullable contains a value!
+             You can do so manually by using #HasValue() or simply operator #bool().
+             Alternatively, if checked access is needed, #GetValue() or #ValueOr() may be used.
+     */
+    constexpr const T&& operator*() const&& { return std::move(m_value); }
 
     /**
      * @brief Get the contained value, returns \p other if value is absent.

sdk/core/azure-core/test/ut/modified_conditions.cpp

@@ -18,9 +18,9 @@ TEST(ModifiedConditions, Basic)
       = DateTime::Parse("2013-11-19T14:30:59.1234567Z", DateTime::DateFormat::Rfc3339);
 
   EXPECT_EQ(
-      conditions.IfModifiedSince.ToString(DateTime::DateFormat::Rfc3339),
+      conditions.IfModifiedSince->ToString(DateTime::DateFormat::Rfc3339),
       "2013-11-19T14:30:59.1234567Z");
   EXPECT_EQ(
-      conditions.IfUnmodifiedSince.ToString(DateTime::DateFormat::Rfc3339),
+      conditions.IfUnmodifiedSince->ToString(DateTime::DateFormat::Rfc3339),
       "2013-11-19T14:30:59.1234567Z");
 }