src/qpid/framing/SequenceNumber.h

/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 */
#ifndef _framing_SequenceNumber_h
#define _framing_SequenceNumber_h

#include "qpid/framing/amqp_types.h"
#include <boost/operators.hpp>
#include <iosfwd>
#include "qpid/CommonImportExport.h"

namespace qpid {
namespace framing {

class Buffer;

/**
 * 4-byte sequence number that 'wraps around'.
 */
class QPID_COMMON_CLASS_EXTERN SequenceNumber : public
boost::equality_comparable<
    SequenceNumber, boost::less_than_comparable<
        SequenceNumber, boost::incrementable<
        SequenceNumber, boost::decrementable<SequenceNumber> > > >
{
    int32_t value;

  public:
    SequenceNumber(uint32_t v=0) : value(v) {}

    SequenceNumber& operator++() { ++value; return *this; }
    SequenceNumber& operator--() { --value; return *this; }
    bool operator==(const SequenceNumber& other) const { return value == other.value; }
    bool operator<(const SequenceNumber& other) const { return (value - other.value) < 0; }
    uint32_t getValue() const { return uint32_t(value); }
    operator uint32_t() const { return uint32_t(value); }

    QPID_COMMON_EXTERN void encode(Buffer& buffer) const;
    QPID_COMMON_EXTERN void decode(Buffer& buffer);
    QPID_COMMON_EXTERN uint32_t encodedSize() const;

    template <class S> void serialize(S& s) { s(value); }
};

inline int32_t operator-(const SequenceNumber& a, const SequenceNumber& b) {
    return int32_t(a.getValue() - b.getValue());
}

inline SequenceNumber operator+(const SequenceNumber& a, int32_t n) {
    return SequenceNumber(a.getValue() + n);
}

inline SequenceNumber operator-(const SequenceNumber& a, int32_t n) {
    return SequenceNumber(a.getValue() - n);
}

struct Window
{
    SequenceNumber hwm;
    SequenceNumber lwm;
};

QPID_COMMON_EXTERN std::ostream& operator<<(std::ostream& o, const SequenceNumber& n);

}} // namespace qpid::framing


#endif