diff -r 28294b895e5e -r 68a281aefa76 src/lib/AbstractParser.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/lib/AbstractParser.h	Sat Jul 24 17:35:27 2021 +0200
@@ -0,0 +1,126 @@
+/**
+ * Relational pipes
+ * Copyright © 2021 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, version 3 of the License.
+ *
+ * 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 <cstring>
+#include <cstdint>
+
+namespace relpipe {
+namespace in {
+namespace asn1 {
+namespace lib {
+
+class AbstractParserImpl;
+
+/**
+ * Event-driven parser that consumes sequence of byte buffers (chunked stream)
+ * and produces some output (implementation specific).
+ * 
+ * The flow is controlled from outside: incomming data pieces are passed to the parser through the write() method as they come.
+ * 
+ * From the child class perspective (implementation of particular parser)
+ * data pieces are obtained through the read() method from the internal buffer maintained by AbstractParser.
+ */
+class AbstractParser {
+private:
+	friend AbstractParserImpl;
+	AbstractParserImpl* implementation;
+	void rollback();
+public:
+	virtual ~AbstractParser();
+
+	/**
+	 * Submit a part of incomming data to the parser.
+	 * When possible, such data are usually processed synchronously during this method call.
+	 * If not (incomplete TLV/AVP/PDU/token/etc.) this part is appended to the internal buffer maintained by AbstractParser
+	 * and processed in some next cycle or – in worst case – during the close() call.
+	 * 
+	 * @param buffer readable memory
+	 * @param length size of the buffer
+	 */
+	void write(const uint8_t* buffer, const size_t length);
+
+	/**
+	 * Finalize the parsing process.
+	 * After calling this method, all data from AbstractParser buffers should be consumed, parsed and results published.
+	 * No write() call is expected after close() and would fail.
+	 * However the parser object remains valid and may be used to get some auxiliary information (if supperted by given implementation).
+	 */
+	virtual void close();
+protected:
+	AbstractParser();
+
+	/**
+	 * May be thrown from the update() method in order to cancel currenty cycle and do explicit rollback.
+	 * Same data will be processed in the next cycle.
+	 */
+	class ExplicitRollbackException {
+		// TODO: common super-class for exceptions, hidden implementation
+	};
+
+	/**
+	 * May be called from the update() method in order to explicitly confirm that read data was successfully processed.
+	 * Such data will not be processed again during the next cycle (even if ReadBufferUnderflowException occurs later in this cycle).
+	 
+	 * Explicit commit() call is useful when we did some demanding work (so we are not willing to do it again in case of ReadBufferUnderflowException);
+	 * and is necessary when we already published some outputs or did other non-idempotent operation or caused some other significant side effects.
+	 
+	 * If there is no commit() called and update() just finishes, commit() is called implicitly.
+	 * 
+	 * Note: There is no accessible rollback() method – throw ExplicitRollbackException instead.
+	 */
+	void commit();
+
+	/**
+	 * Fill the buffer with incomming data of given length (exactly).
+	 * 
+	 * If there are not enough data available, ReadBufferUnderflowException is thrown.
+	 * This exception should not be caught in the child class – it should propagate back to the AbstractParser
+	 * where it causes rollback(). In such case, the same data will be available during next update() cycle.
+	 * 
+	 * @param buffer writable memory
+	 * @param length size of the buffer
+	 */
+	void read(uint8_t* buffer, const size_t length);
+
+	/**
+	 * Like read(), but does not update the marks (buffer positions), so it can be called again and again with same result.
+	 * 
+	 * @param buffer writable memory
+	 * @param length size of the buffer
+	 */
+	void peek(uint8_t* buffer, const size_t length);
+
+	/**
+	 * @return total number of bytes that were successfully read
+	 */
+	size_t getBytesRead();
+
+	/**
+	 * Reads input from buffers using read(), parses data and usually emits the result (e.g. to a handler/listener).
+	 * Is specific for particular format/parser.
+	 * 
+	 * This method is called at least once at the end of the stream (with whole stream content in read buffers).
+	 * Usually it is called more often, by default: after each write (with just already received data part in read buffers).
+	 */
+	virtual void update() = 0;
+};
+
+}
+}
+}
+}