add a CSVConnector/CSVExpression classes to serialize to csv format

Current limitation: list/vectors are not serialized.

while here:
- move the output_type flag from the DbExpression to BaseExpression class
- add Model::to_text(...) methods with an Export parameter

src/export.h

@@ -0,0 +1,128 @@
+/*
+ * This file is a part of morm
+ * and is distributed under the 2-Clause BSD licence.
+ * Author: Tomasz Sowa <t.sowa@ttmath.org>
+ */
+
+/*
+ * Copyright (c) 2023, Tomasz Sowa
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWAExportType, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef headerfile_morm_src_export
+#define headerfile_morm_src_export
+
+namespace morm
+{
+
+
+
+/*
+ * field types
+ */
+class Export
+{
+public:
+
+	enum ExportType
+	{
+		default_type = 0,
+		no_clear_stream = 1,
+		dump_mode = 2,
+		export_headers = 4,
+	};
+
+	/*
+	 * type can be a superposition from ExportType values
+	 */
+	int type;
+
+
+
+	Export()
+	{
+		type = 0;
+	}
+
+	Export(const Export & field_type)
+	{
+		type = field_type.type;
+	}
+
+	Export(ExportType type)
+	{
+		this->type = static_cast<int>(type);
+	}
+
+	Export(int type)
+	{
+		this->type = type;
+	}
+
+	Export & operator=(const Export & field_type)
+	{
+		type = field_type.type;
+		return *this;
+	}
+
+	Export & operator=(ExportType type)
+	{
+		this->type = static_cast<int>(type);
+		return *this;
+	}
+
+	Export & operator=(int type)
+	{
+		this->type = type;
+		return *this;
+	}
+
+	bool is_flag_set(int flag_mask) const
+	{
+		return (type & flag_mask) != 0;
+	}
+
+	bool is_no_clear_stream() const
+	{
+		return is_flag_set(no_clear_stream);
+	}
+
+	bool is_dump_mode() const
+	{
+		return is_flag_set(dump_mode);
+	}
+
+	bool is_export_headers() const
+	{
+		return is_flag_set(export_headers);
+	}
+
+};
+
+}
+
+#endif
+