diff -r 000000000000 -r f4f9cdf7ed59 src/ASN1Writer.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ASN1Writer.h	Sat Mar 30 01:12:42 2019 +0100
@@ -0,0 +1,97 @@
+/**
+ * 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 <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+#include <codecvt>
+#include <locale>
+
+#include <relpipe/reader/typedefs.h>
+#include <relpipe/cli/RelpipeCLIException.h>
+
+using namespace std;
+
+namespace relpipe {
+namespace out {
+namespace asn1 {
+
+using namespace relpipe::reader;
+
+/**
+ * A simple library for writing ASN.1 BER encoded files.
+ */
+class ASN1Writer {
+private:
+	ostream& output;
+	wstring_convert<codecvt_utf8<wchar_t>> convertor; // only UTF8String is supported
+	int sequenceLevel = 0;
+
+	void xxx_indent() {
+		// FIXME: remove
+		for (int i = 0; i < sequenceLevel; i++) output << "  ";
+	}
+
+public:
+
+	ASN1Writer(std::ostream& output) : output(output) {
+	}
+
+	virtual ~ASN1Writer() {
+		if (sequenceLevel) output << "Unable to close ASN1Writer because there are not ended sequences." << endl; // FIXME: better error handling
+		output.flush();
+	}
+
+	void writeStartSequence() {
+		xxx_indent();
+		output << "sequence start" << endl;
+
+		sequenceLevel++;
+	}
+
+	void writeEndSequence() {
+		if (sequenceLevel == 0) throw cli::RelpipeCLIException(L"Unable to writeEndSequence() if not sequence is currently started.", cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // should not happen, error in the program
+
+		sequenceLevel--;
+
+		xxx_indent();
+		output << "sequence end" << endl;
+	}
+
+	void writeBoolean(const boolean_t& value) {
+		xxx_indent();
+		output << "boolean" << (value ? "true" : "false") << endl;
+	}
+
+	void writeInteger(const integer_t& value) {
+		xxx_indent();
+		output << "integer: " << value << endl;
+	}
+
+	void writeString(const string_t& value) {
+		xxx_indent();
+		output << "string: " << convertor.to_bytes(value) << endl;
+	}
+
+};
+
+}
+}
+}
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