Merge pull request #135 from cbeiraod/master

Adding std::experimental::optional

Author: aminroosta

README.md

@@ -325,6 +325,8 @@ int main() {
 
 If you do not have C++17 support, you can use boost optional instead by defining `_MODERN_SQLITE_BOOST_OPTIONAL_SUPPORT` before importing the `sqlite_modern_cpp` header.
 
+If the optional library is not available, the experimental/optional one will be used instead.
+
 **Note: boost support is deprecated and will be removed in future versions.**
 
 Variant type support (C++17)

hdr/sqlite_modern_cpp.h

@@ -16,6 +16,8 @@
 #ifdef __has_include
 #if __cplusplus > 201402 && __has_include(<optional>)
 #define MODERN_SQLITE_STD_OPTIONAL_SUPPORT
+#elif __has_include(<experimental/optional>)
+#define MODERN_SQLITE_EXPERIMENTAL_OPTIONAL_SUPPORT
 #endif
 #endif
 
@@ -29,6 +31,11 @@
 #include <optional>
 #endif
 
+#ifdef MODERN_SQLITE_EXPERIMENTAL_OPTIONAL_SUPPORT
+#include <experimental/optional>
+#define MODERN_SQLITE_STD_OPTIONAL_SUPPORT
+#endif
+
 #ifdef _MODERN_SQLITE_BOOST_OPTIONAL_SUPPORT
 #include <boost/optional.hpp>
 #endif
@@ -44,6 +51,18 @@
 #endif
 
 namespace sqlite {
+
+		// std::optional support for NULL values
+	#ifdef MODERN_SQLITE_STD_OPTIONAL_SUPPORT
+	#ifdef MODERN_SQLITE_EXPERIMENTAL_OPTIONAL_SUPPORT
+	template<class T>
+	using optional = std::experimental::optional<T>;
+	#else
+	template<class T>
+	using optional = std::optional<T>;
+	#endif
+	#endif
+
 	class database;
 	class database_binder;
 
@@ -238,8 +257,8 @@ namespace sqlite {
 
 
 #ifdef MODERN_SQLITE_STD_OPTIONAL_SUPPORT
-		template <typename OptionalT> friend database_binder& operator <<(database_binder& db, const std::optional<OptionalT>& val);
-		template <typename OptionalT> friend void get_col_from_db(database_binder& db, int inx, std::optional<OptionalT>& o);
+		template <typename OptionalT> friend database_binder& operator <<(database_binder& db, const optional<OptionalT>& val);
+		template <typename OptionalT> friend void get_col_from_db(database_binder& db, int inx, optional<OptionalT>& o);
 #endif
 
 #ifdef _MODERN_SQLITE_BOOST_OPTIONAL_SUPPORT
@@ -790,32 +809,40 @@ namespace sqlite {
 
 	// std::optional support for NULL values
 #ifdef MODERN_SQLITE_STD_OPTIONAL_SUPPORT
-	template <typename OptionalT> inline database_binder& operator <<(database_binder& db, const std::optional<OptionalT>& val) {
+	template <typename OptionalT> inline database_binder& operator <<(database_binder& db, const optional<OptionalT>& val) {
 		if(val) {
 			return db << std::move(*val);
 		} else {
 			return db << nullptr;
 		}
 	}
-	template <typename OptionalT> inline void store_result_in_db(sqlite3_context* db, const std::optional<OptionalT>& val) {
+	template <typename OptionalT> inline void store_result_in_db(sqlite3_context* db, const optional<OptionalT>& val) {
 		if(val) {
 			store_result_in_db(db, *val);
 		}
 		sqlite3_result_null(db);
 	}
 
-	template <typename OptionalT> inline void get_col_from_db(database_binder& db, int inx, std::optional<OptionalT>& o) {
+	template <typename OptionalT> inline void get_col_from_db(database_binder& db, int inx, optional<OptionalT>& o) {
 		if(sqlite3_column_type(db._stmt.get(), inx) == SQLITE_NULL) {
+			#ifdef MODERN_SQLITE_EXPERIMENTAL_OPTIONAL_SUPPORT
+			o = std::experimental::nullopt;
+			#else
 			o.reset();
+			#endif
 		} else {
 			OptionalT v;
 			get_col_from_db(db, inx, v);
 			o = std::move(v);
 		}
 	}
-	template <typename OptionalT> inline void get_val_from_db(sqlite3_value *value, std::optional<OptionalT>& o) {
+	template <typename OptionalT> inline void get_val_from_db(sqlite3_value *value, optional<OptionalT>& o) {
 		if(sqlite3_value_type(value) == SQLITE_NULL) {
+			#ifdef MODERN_SQLITE_EXPERIMENTAL_OPTIONAL_SUPPORT
+			o = std::experimental::nullopt;
+			#else
 			o.reset();
+			#endif
 		} else {
 			OptionalT v;
 			get_val_from_db(value, v);

tests/std_optional.cc

@@ -8,15 +8,15 @@ using namespace std;
 #ifdef MODERN_SQLITE_STD_OPTIONAL_SUPPORT
 void insert(database& db, bool is_null) {
 	int id = 1;
-	std::optional<int> val;
+	sqlite::optional<int> val;
 	if(!is_null) val = 5;
 
 	db << "delete from test where id = 1";
 	db << "insert into test(id,val) values(?,?)" << id << val;
 }
 
 void select(database& db, bool should_be_null) {
-	db << "select id,val from test" >> [&](long long, std::optional<int> val) {
+	db << "select id,val from test" >> [&](long long, sqlite::optional<int> val) {
 		if(should_be_null) {
 			if(val) exit(EXIT_FAILURE);
 		} else {