--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/AttributeFinder.h Wed Jan 16 17:23:05 2019 +0100
@@ -0,0 +1,97 @@
+/**
+ * Relational pipes
+ * Copyright © 2019 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <vector>
+#include <filesystem>
+
+#include <relpipe/writer/typedefs.h>
+#include <relpipe/writer/AttributeMetadata.h>
+#include <relpipe/writer/RelationalWriter.h>
+
+#include "RequestedField.h"
+
+namespace relpipe {
+namespace in {
+namespace filesystem {
+
+namespace fs = std::filesystem;
+using namespace relpipe::writer;
+
+class AttributeFinder {
+public:
+
+ /**
+ * Single requested fields might generate multiple attributes in the relation.
+ * But usually it is 1:1.
+ * @param field requested field from the user (usually from CLI arguments)
+ * @return attribute metadata to be used in the RelationalWriter.startRelation()
+ */
+ virtual vector<AttributeMetadata> toMetadata(const RequestedField& field) = 0;
+
+ /**
+ * Writing of the record for current file is starting.
+ * Following writeField() calls are related to this file.
+ * @param file
+ */
+ virtual void startFile(const fs::path& file) = 0;
+
+ /**
+ * Writing of the record for current file is finished. All resources linked to this file should be released.
+ */
+ virtual void endFile() = 0;
+
+ /**
+ * Writes field attribute(s). The attribute count must match with count of AttributeMetadata returned in toMetadata().
+ * @param writer
+ * @param field
+ */
+ virtual void writeField(RelationalWriter* writer, const RequestedField& field) = 0;
+
+ /**
+ * Writes empty attribute(s) in case of non-existent file or an error.
+ * The attribute count must match with count of AttributeMetadata returned in toMetadata().
+ * @param writer
+ * @param field
+ */
+ virtual void writeEmptyField(RelationalWriter* writer, const RequestedField& field) {
+ // TODO: better handling of null values (when null values are supported by the format specification)
+ for (AttributeMetadata m : toMetadata(field)) {
+ switch (m.typeId) {
+ case TypeId::BOOLEAN:
+ writer->writeAttribute(L"false");
+ break;
+ case TypeId::INTEGER:
+ writer->writeAttribute(L"0");
+ break;
+ case TypeId::STRING:
+ writer->writeAttribute(L"");
+ break;
+ default:
+ throw RelpipeWriterException(L"Unsupported attribute type in writeEmptyField().");
+ }
+ }
+ }
+
+ virtual ~AttributeFinder() {
+ }
+};
+
+}
+}
+}
\ No newline at end of file