support nullptr and uniqueptr

Author: aminroosta

hdr/sqlite_modern_cpp.h

@@ -210,8 +210,12 @@ namespace sqlite {
 
 		template<typename T> friend database_binder::chain_type& operator <<(database_binder::chain_type& db, const T& val);
 		template<typename T> friend void get_col_from_db(database_binder& db, int inx, T& val);
+		/* for vector<T> support */
 		template<typename T> friend database_binder::chain_type& operator <<(database_binder::chain_type& db, const std::vector<T>& val);
 		template<typename T> friend void get_col_from_db(database_binder& db, int inx, std::vector<T>& val);
+		/* for nullptr & unique_ptr support */
+		friend database_binder::chain_type& operator <<(database_binder::chain_type& db, std::nullptr_t);
+		template<typename T> friend void get_col_from_db(database_binder& db, int inx, std::unique_ptr<T>& val);
 		template<typename T> friend T operator++(database_binder& db, int);
 
 
@@ -458,6 +462,27 @@ namespace sqlite {
 		}
 	}
 
+	/* for nullptr support */
+	inline database_binder::chain_type& operator <<(database_binder::chain_type& db, std::nullptr_t) {
+		int hresult;
+		if((hresult = sqlite3_bind_null(db->_stmt.get(), db->_inx)) != SQLITE_OK) {
+			exceptions::throw_sqlite_error(hresult);
+		}
+		++db->_inx;
+		return db;
+	}
+
+	/* for unique_ptr<T> support */
+	template<typename T> inline void get_col_from_db(database_binder& db, int inx, std::unique_ptr<T>& _ptr_) {
+		if(sqlite3_column_type(db._stmt.get(), inx) == SQLITE_NULL) {
+			_ptr_ = nullptr;
+		} else {
+			auto underling_ptr = new T();
+			get_col_from_db(db, inx, *underling_ptr);
+			_ptr_.reset(underling_ptr);
+		}
+	}
+
 	// std::string
 	template<> inline void get_col_from_db(database_binder& db, int inx, std::string & s) {
 		if(sqlite3_column_type(db._stmt.get(), inx) == SQLITE_NULL) {

tests/nullptr_uniqueptr.cc

@@ -0,0 +1,46 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <sqlite_modern_cpp.h>
+using namespace std;
+using namespace sqlite;
+
+int main() {
+
+	try {
+		database db(":memory:");
+		db << "CREATE TABLE tbl (id integer,age integer, name string, img blob);";
+		db << "INSERT INTO tbl VALUES (?, ?, ?, ?);" << 1 << 24 << "bob" << vector<int> { 1, 2 , 3};
+		db << "INSERT INTO tbl VALUES (?, ?, ?, ?);" << 2 << nullptr << nullptr << nullptr;
+
+		db << "select age,name,img from tbl where id = 1" >> [](unique_ptr<int> age_p, unique_ptr<string> name_p, unique_ptr<vector<int>> img_p) {
+      if(age_p == nullptr || name_p == nullptr || img_p == nullptr) {
+        cerr << "ERROR: values should not be null" << std::endl;
+        exit(EXIT_FAILURE);
+      }
+
+      cout << "age:" << *age_p << " name:" << *name_p << " img:";
+      for(auto i : *img_p) cout << i << ","; cout << endl;
+		};
+
+		db << "select age,name,img from tbl where id = 2" >> [](unique_ptr<int> age_p, unique_ptr<string> name_p, unique_ptr<vector<int>> img_p) {
+      if(age_p != nullptr || name_p != nullptr || img_p != nullptr) {
+        cerr << "ERROR: values should be nullptr" << std::endl;
+        exit(EXIT_FAILURE);
+      }
+
+      cout << "OK all three values are nullptr" << endl;
+		};
+
+	} catch(sqlite_exception e) {
+		cout << "Sqlite error " << e.what() << endl;
+		exit(EXIT_FAILURE);
+	} catch(...) {
+		cout << "Unknown error\n";
+		exit(EXIT_FAILURE);
+	}
+
+	cout << "OK\n";
+	exit(EXIT_SUCCESS);
+  return 0;
+}