Use std::optional if available.

Currently, SDK requires C++11 minimum.
So, boost::optional type is used for optional values.
For C++17 and above more convenient is to use std::optional instead.
The task NLAM-23 is about making this type configurable.
This PR is a first part of the task: olp-cpp-sdk-core.

Relates-To: NLAM-23
Signed-off-by: sopov <[email protected]>

Author: asopov-here

CMakeLists.txt

@@ -37,6 +37,7 @@ endif()
 option(OLP_SDK_ENABLE_TESTING "Flag to enable/disable building unit and integration tests" ON)
 option(OLP_SDK_BUILD_DOC "Build SDK documentation" OFF)
 option(OLP_SDK_NO_EXCEPTION "Disable exception handling" OFF)
+option(OLP_SDK_FORCE_BOOST_OPTIONAL "Use boost::optional instead of std::optional with C++17 and above" OFF)
 option(OLP_SDK_BOOST_THROW_EXCEPTION_EXTERNAL "The boost::throw_exception() is defined externally" OFF)
 option(OLP_SDK_BUILD_EXTERNAL_DEPS "Download and build external dependencies" ON)
 option(OLP_SDK_BUILD_EXAMPLES "Enable examples targets" OFF)

CONTRIBUTING.md

@@ -257,12 +257,13 @@ inline PublishDataRequest& WithLayerId(std::string&& layer_id) {
 
 #### API optional parameters
 
-The SDK uses `boost::optional` for optional members, parameters, or return types. Also, function comments should indicate whether the parameter is optional or required.
+The SDK uses `porting::optional` mapped to either `boost::optional` or `std::optional` for optional members,
+parameters, or return types. Also, function comments should indicate whether the parameter is optional or required.
 
 Example:
 
 ```cpp
-inline const boost::optional<std::string>& GetBillingTag() const {
+inline const porting::optional<std::string>& GetBillingTag() const {
   return billing_tag_;
 }
 

external/CMakeLists.txt

@@ -97,7 +97,7 @@ if(OLP_SDK_ENABLE_DEFAULT_CACHE_LMDB)
     endif()
 endif()
 
-find_package(Boost QUIET)
+find_package(Boost 1.82.0 QUIET)
 if(NOT TARGET Boost AND NOT Boost_FOUND)
     add_subdirectory(boost)
     set(BOOST_ROOT ${EXTERNAL_BOOST_ROOT} PARENT_SCOPE)

olp-cpp-sdk-core/CMakeLists.txt

@@ -131,6 +131,7 @@ set(OLP_SDK_PORTING_HEADERS
     ./include/olp/core/porting/deprecated.h
     ./include/olp/core/porting/export.h
     ./include/olp/core/porting/make_unique.h
+    ./include/olp/core/porting/optional.hpp
     ./include/olp/core/porting/platform.h
     ./include/olp/core/porting/shared_mutex.h
     ./include/olp/core/porting/try_emplace.h
@@ -439,6 +440,11 @@ if (OLP_SDK_NO_EXCEPTION AND NOT OLP_SDK_BOOST_THROW_EXCEPTION_EXTERNAL)
         PRIVATE OLP_SDK_BOOST_THROW_EXCEPTION=1)
 endif()
 
+if (OLP_SDK_FORCE_BOOST_OPTIONAL)
+    target_compile_definitions(${PROJECT_NAME}
+        PUBLIC OLP_CPP_SDK_USE_BOOST_OPTIONAL)
+endif()
+
 target_include_directories(${PROJECT_NAME} PUBLIC
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>

olp-cpp-sdk-core/include/olp/core/cache/CacheSettings.h

@@ -25,8 +25,7 @@
 #include <olp/core/Config.h>
 #include <olp/core/CoreApi.h>
 
-#include <olp/core/porting/deprecated.h>
-#include <boost/optional.hpp>
+#include <olp/core/porting/optional.hpp>
 
 namespace olp {
 namespace cache {
@@ -72,7 +71,7 @@ struct CORE_API CacheSettings {
    * If this parameter is not set, the downloaded data is stored
    * only in the memory cache that is limited by `#max_memory_cache_size`.
    */
-  boost::optional<std::string> disk_path_mutable = boost::none;
+  porting::optional<std::string> disk_path_mutable = porting::none;
 
   /**
    * @brief Sets the upper limit (in bytes) of the disk space that is used for
@@ -161,7 +160,7 @@ struct CORE_API CacheSettings {
    * have a stable fallback state or offline data that you can always access
    * regardless of the network state.
    */
-  boost::optional<std::string> disk_path_protected = boost::none;
+  porting::optional<std::string> disk_path_protected = porting::none;
 
   /**
    * @brief The extend permissions flag (applicable for Unix systems).

olp-cpp-sdk-core/include/olp/core/cache/KeyGenerator.h

@@ -22,9 +22,8 @@
 #include <string>
 
 #include <olp/core/CoreApi.h>
-#include <olp/core/client/HRN.h>
 #include <olp/core/geo/tiling/TileKey.h>
-#include <boost/optional.hpp>
+#include <olp/core/porting/optional.hpp>
 
 namespace olp {
 namespace cache {
@@ -77,7 +76,7 @@ class CORE_API KeyGenerator {
    */
   static std::string CreatePartitionKey(
       const std::string& hrn, const std::string& layer_id,
-      const std::string& partition_id, const boost::optional<int64_t>& version);
+      const std::string& partition_id, const porting::optional<int64_t>& version);
 
   /**
    * @brief Generates cache key for storing list of partitions.
@@ -90,7 +89,7 @@ class CORE_API KeyGenerator {
    */
   static std::string CreatePartitionsKey(
       const std::string& hrn, const std::string& layer_id,
-      const boost::optional<int64_t>& version);
+      const porting::optional<int64_t>& version);
 
   /**
    * @brief Generates cache key for storing list of available layer versions.
@@ -117,7 +116,7 @@ class CORE_API KeyGenerator {
   static std::string CreateQuadTreeKey(const std::string& hrn,
                                        const std::string& layer_id,
                                        olp::geo::TileKey root,
-                                       const boost::optional<int64_t>& version,
+                                       const porting::optional<int64_t>& version,
                                        int32_t depth);
 
   /**

olp-cpp-sdk-core/include/olp/core/client/OlpClientSettings.h

@@ -24,10 +24,9 @@
 #include <memory>
 #include <string>
 
-#include <boost/optional.hpp>
+#include <olp/core/porting/optional.hpp>
 
 #include <olp/core/client/CancellationContext.h>
-#include <olp/core/client/CancellationToken.h>
 #include <olp/core/client/DefaultLookupEndpointProvider.h>
 #include <olp/core/client/HRN.h>
 #include <olp/core/client/HttpResponse.h>
@@ -191,16 +190,16 @@ struct CORE_API OlpClientSettings {
   /**
    * @brief The network proxy settings.
    *
-   * To remove any existing proxy settings, set to `boost::none`.
+   * To remove any existing proxy settings, set to `olp::porting::none`.
    */
-  boost::optional<http::NetworkProxySettings> proxy_settings = boost::none;
+  porting::optional<http::NetworkProxySettings> proxy_settings = porting::none;
 
   /**
    * @brief The authentication settings.
    *
-   * To remove any existing authentication settings, set to `boost::none`.
+   * To remove any existing authentication settings, set to `olp::porting::none`.
    */
-  boost::optional<AuthenticationSettings> authentication_settings = boost::none;
+  porting::optional<AuthenticationSettings> authentication_settings = porting::none;
 
   /**
    * @brief The `TaskScheduler` instance.

olp-cpp-sdk-core/include/olp/core/client/OlpClientSettingsFactory.h

@@ -22,8 +22,6 @@
 #include <memory>
 #include <string>
 
-#include <boost/optional.hpp>
-
 #include "olp/core/CoreApi.h"
 #include "olp/core/http/Network.h"
 #include "olp/core/http/NetworkInitializationSettings.h"

olp-cpp-sdk-core/include/olp/core/generated/parser/ParserWrapper.h

@@ -25,7 +25,7 @@
 #include <vector>
 
 #include <rapidjson/rapidjson.h>
-#include <boost/optional.hpp>
+#include <olp/core/porting/optional.hpp>
 
 namespace olp {
 namespace parser {
@@ -57,7 +57,8 @@ inline void from_json(const rapidjson::Value& value,
 }
 
 template <typename T>
-inline void from_json(const rapidjson::Value& value, boost::optional<T>& x) {
+inline void from_json(const rapidjson::Value& value,
+                      porting::optional<T>& x) {
   T result = T();
   from_json(value, result);
   x = result;

olp-cpp-sdk-core/include/olp/core/generated/serializer/SerializerWrapper.h

@@ -25,7 +25,7 @@
 #include <vector>
 #include <utility>
 
-#include <boost/optional.hpp>
+#include <olp/core/porting/optional.hpp>
 #include <rapidjson/document.h>
 
 namespace olp {
@@ -63,10 +63,10 @@ inline void to_json(const std::shared_ptr<std::vector<unsigned char>>& x,
 }
 
 template <typename T>
-inline void to_json(const boost::optional<T>& x, rapidjson::Value& value,
+inline void to_json(const porting::optional<T>& x, rapidjson::Value& value,
                     rapidjson::Document::AllocatorType& allocator) {
   if (x) {
-    to_json(x.get(), value, allocator);
+    to_json(*x, value, allocator);
   } else {
     value.SetNull();
   }