diff -r f66c759d1111 -r f06781a5071b src/CutHandler.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/CutHandler.h	Wed Dec 12 23:45:46 2018 +0100
@@ -0,0 +1,124 @@
+/**
+ * Relational pipes
+ * Copyright © 2018 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 <memory>
+#include <string>
+#include <vector>
+#include <iostream>
+#include <sstream>
+#include <locale>
+#include <codecvt>
+#include <regex>
+
+#include <relpipe/reader/typedefs.h>
+#include <relpipe/reader/TypeId.h>
+#include <relpipe/reader/handlers/RelationalReaderStringHandler.h>
+#include <relpipe/reader/handlers/AttributeMetadata.h>
+
+#include <relpipe/writer/Factory.h>
+
+#include <relpipe/cli/RelpipeCLIException.h>
+
+namespace relpipe {
+namespace tr {
+namespace grep {
+
+using namespace std;
+using namespace relpipe;
+using namespace relpipe::reader;
+using namespace relpipe::reader::handlers;
+
+class GrepHandler : public RelationalReaderStringHadler {
+private:
+	shared_ptr<writer::RelationalWriter> relationalWriter;
+
+	wregex relationNameRegEx;
+	wregex attributeNameRegEx;
+	wregex searchRegEx;
+
+	vector<boolean_t> currentSearchableAttributes;
+	vector<string_t> currentRecord;
+	integer_t currentAttributeIndex = 0;
+	boolean_t includeCurrentRecord = false;
+	boolean_t filterCurrentRelation = false;
+
+public:
+
+	GrepHandler(ostream& output, const vector<string_t>& arguments) {
+		relationalWriter.reset(writer::Factory::create(output));
+
+		if (arguments.size() == 3) {
+			relationNameRegEx = wregex(arguments[0]);
+			attributeNameRegEx = wregex(arguments[1]);
+			searchRegEx = wregex(arguments[2]);
+		} else {
+			throw cli::RelpipeCLIException(L"Usage: relpipe-tr-cut <relationNameRegExp> <attributeNameRegExp> <searchRegExp>", cli::CLI::EXIT_CODE_UNKNOWN_COMMAND);
+		}
+	}
+
+	void startRelation(string_t name, vector<AttributeMetadata> attributes) override {
+		// TODO: move to a reusable method (or use same metadata on both reader and writer side?)
+		vector<writer::AttributeMetadata> writerMetadata;
+		for (AttributeMetadata readerMetadata : attributes) {
+			writerMetadata.push_back({readerMetadata.getAttributeName(), relationalWriter->toTypeId(readerMetadata.getTypeName())});
+		}
+
+
+		currentRecord.resize(attributes.size());
+		currentSearchableAttributes.resize(attributes.size(), false);
+		filterCurrentRelation = regex_match(name, relationNameRegEx);
+		if (filterCurrentRelation) {
+			for (int i = 0; i < currentSearchableAttributes.size(); i++) {
+				currentSearchableAttributes[i] = regex_match(attributes[i].getAttributeName(), attributeNameRegEx);
+			}
+		}
+
+		relationalWriter->startRelation(name, writerMetadata, true);
+	}
+
+	void attribute(const string_t& value) override {
+		if (filterCurrentRelation) {
+			currentRecord[currentAttributeIndex] = value;
+
+			if (currentSearchableAttributes[currentAttributeIndex]) {
+				includeCurrentRecord |= regex_search(value, searchRegEx);
+			}
+
+			currentAttributeIndex++;
+
+			if (currentAttributeIndex > 0 && currentAttributeIndex % currentSearchableAttributes.size() == 0) {
+				if (includeCurrentRecord) for (string_t v : currentRecord) relationalWriter->writeAttribute(v);
+				includeCurrentRecord = false;
+			}
+
+			currentAttributeIndex = currentAttributeIndex % currentSearchableAttributes.size();
+		} else {
+			relationalWriter->writeAttribute(value);
+		}
+	}
+
+	void endOfPipe() {
+
+	}
+
+};
+
+}
+}
+}