diff options
author | Martin Sustrik <sustrik@fastmq.commkdir> | 2009-07-29 12:07:54 +0200 |
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committer | Martin Sustrik <sustrik@fastmq.commkdir> | 2009-07-29 12:07:54 +0200 |
commit | 4ed70a930202b103e7e80b8dc925e0aaa4622595 (patch) | |
tree | aeed881ce17629f81b7c90f7d675aac8ecf69d4f /src/decoder.hpp |
initial commit
Diffstat (limited to 'src/decoder.hpp')
-rw-r--r-- | src/decoder.hpp | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/src/decoder.hpp b/src/decoder.hpp new file mode 100644 index 0000000..c643df8 --- /dev/null +++ b/src/decoder.hpp @@ -0,0 +1,101 @@ +/* + Copyright (c) 2007-2009 FastMQ Inc. + + This file is part of 0MQ. + + 0MQ is free software; you can redistribute it and/or modify it under + the terms of the Lesser GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + 0MQ 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 + Lesser GNU General Public License for more details. + + You should have received a copy of the Lesser GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +#ifndef __ZS_DECODER_HPP_INCLUDED__ +#define __ZS_DECODER_HPP_INCLUDED__ + +#include <stddef.h> +#include <string.h> +#include <algorithm> + +namespace zs +{ + + // Helper base class for decoders that know the amount of data to read + // in advance at any moment. Knowing the amount in advance is a property + // of the protocol used. Both AMQP and backend protocol are based on + // size-prefixed paradigm, therefore they are using decoder_t to parse + // the messages. On the other hand, XML-based transports (like XMPP or + // SOAP) don't allow for knowing the size of data to read in advance and + // should use different decoding algorithms. + // + // Decoder implements the state machine that parses the incoming buffer. + // Derived class should implement individual state machine actions. + + template <typename T> class decoder_t + { + public: + + inline decoder_t () : + read_ptr (NULL), + to_read (0), + next (NULL) + { + } + + // Push the binary data to the decoder. Returns number of bytes + // actually parsed. + inline size_t write (unsigned char *data_, size_t size_) + { + size_t pos = 0; + while (true) { + size_t to_copy = std::min (to_read, size_ - pos); + if (read_ptr) { + memcpy (read_ptr, data_ + pos, to_copy); + read_ptr += to_copy; + } + pos += to_copy; + to_read -= to_copy; + while (!to_read) + if (!(static_cast <T*> (this)->*next) ()) + return pos; + if (pos == size_) + return pos; + } + } + + protected: + + // Prototype of state machine action. Action should return false if + // it is unable to push the data to the system. + typedef bool (T::*step_t) (); + + // This function should be called from derived class to read data + // from the buffer and schedule next state machine action. + inline void next_step (void *read_ptr_, size_t to_read_, + step_t next_) + { + read_ptr = (unsigned char*) read_ptr_; + to_read = to_read_; + next = next_; + } + + private: + + unsigned char *read_ptr; + size_t to_read; + step_t next; + + decoder_t (const decoder_t&); + void operator = (const decoder_t&); + }; + +} + +#endif |