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/csvexpression.cpp

@@ -0,0 +1,97 @@
+/*
+ * 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 SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "csvexpression.h"
+#include "morm_types.h"
+#include "convert/misc.h"
+
+
+namespace morm
+{
+
+
+bool CSVExpression::can_field_list_be_generated(const FT &)
+{
+	return false;
+}
+
+
+void CSVExpression::field_before()
+{
+	BaseExpression::field_before();
+
+	if( !is_first_field )
+	{
+		(*out_stream) << ",";
+	}
+}
+
+
+void CSVExpression::after_generate_from_model()
+{
+	(*out_stream) << ",";
+}
+
+
+void CSVExpression::before_field_name()
+{
+	(*out_stream) << '"';
+}
+
+
+void CSVExpression::after_field_name()
+{
+	(*out_stream) << '"';
+}
+
+
+void CSVExpression::before_field_value_string(const FT & field_type, ModelEnv * model_env)
+{
+	(*out_stream) << '"';
+}
+
+
+void CSVExpression::after_field_value_string(const FT & field_type, ModelEnv * model_env)
+{
+	(*out_stream) << '"';
+}
+
+
+bool CSVExpression::esc_char(wchar_t val, pt::TextStream & stream, const FT & field_type, ModelEnv * model_env)
+{
+	return pt::try_esc_to_csv(val, stream);
+}
+
+
+}