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#ifndef QPID_SERIALIZER_H
#define QPID_SERIALIZER_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.
*
*/
#include <limits>
#include <algorithm>
#include "qpid/Exception.h" // FIXME aconway 2008-04-03: proper exception class.
namespace qpid {
/**
* Overload for types that do not provide a serialize() member.
* It should retrun a wrapper holding a reference to t that implements
* serialize()
*/
template <class T> T& serializable(T& t) { return t; }
/** Serialize std::pair */
template <class T, class U> struct SerializablePair {
std::pair<T,U>& value;
SerializablePair(std::pair<T,U>& x) : value(x) {}
template <class S> void serialize(S& s) { s(value.first)(value.second); }
};
template <class T, class U>
SerializablePair<T,U> serializable(std::pair<T,U>& p) {
return SerializablePair<T,U>(p);
}
/**
* Base class for all serializers.
* Derived serializers inherit from either Encoder or Decoder.
* Serializers can be used as functors or static_visitors.
*/
template <class Derived> class Serializer {
public:
/** Temporarily set a lower relative limit on the serializer */
class ScopedLimit {
public:
ScopedLimit(Serializer& s, size_t l)
: serializer(s), save(serializer.setLimit(l)) {}
~ScopedLimit() { serializer.setAbsLimit(save); }
private:
Serializer& serializer;
size_t save;
};
static size_t maxLimit() { return std::numeric_limits<size_t>::max(); }
Serializer() : bytes(0), limit(maxLimit()) {}
typedef Derived& result_type; // unary functor requirement.
/** Wrapper functor to pass serializer functors by reference. */
template <class S> struct Ref {
typedef typename S::result_type result_type;
S& s;
Ref(S& ss) : s(ss) {}
template <class T> result_type operator()(T& x) { return s(x); }
template <class T> result_type operator()(const T& x) { return s(x); }
};
/** Reference wrapper to pass serializers by reference,
* e.g. to std:: functions that take functors.
*/
template <class S> static Ref<S> ref(S& s) { return Ref<S>(s); }
/** Generic rule to serialize an iterator range */
template <class Iter> Derived& operator()(Iter begin, Iter end) {
std::for_each(begin, end, ref(this->self()));
return self();
}
/** Set limit relative to current position.
* @return old absolute limit.
*/
size_t setLimit(size_t n) {
size_t l=limit;
limit = bytes+n;
return l;
}
/** Get the max number of bytes that can be processed under the
* current limit.
*/
size_t bytesRemaining() const {
return limit - bytes;
}
/** Set absolute limit. */
void setAbsLimit(size_t n) {
limit = n;
if (bytes > limit)
throw Exception("Framing error: data overrun"); // FIXME aconway 2008-04-03: proper exception.
}
protected:
Derived& self() { return *static_cast<Derived*>(this); }
void addBytes(size_t n) {
size_t newBytes=bytes+n;
if (newBytes > limit)
throw Exception("Framing error: data overrun"); // FIXME aconway 2008-04-03: proper exception.
bytes = newBytes;
}
private:
void checkLimit() {
}
size_t bytes; // how many bytes serialized.
size_t limit; // bytes may not exceed this limit.
};
/**
* Base class for encoders, provides generic encode functions.
*
* A derived encoder must provide operator(const T&) to encode all
* primitive types T.
*/
template <class Derived> class EncoderBase : public Serializer<Derived> {
public:
using Serializer<Derived>::operator();
using Serializer<Derived>::self;
/** Default op() for non-primitive types. */
template <class T> Derived& operator()(const T& t) {
serializable(const_cast<T&>(t)).serialize(self()); return self();
}
/** Split serialize() into encode()/decode() */
template <class T> Derived& split(const T& t) {
t.encode(self()); return self();
}
};
/**
* Base class for decoders, provides generic decode functions.
*
* A derived encoder must provide operator(T&) to encode all
* primitive types T.
*/
template <class Derived> class DecoderBase : public Serializer<Derived> {
public:
using Serializer<Derived>::operator();
using Serializer<Derived>::self;
/** Default op() for non-primitive types. */
template <class T> Derived& operator()(T& t) {
serializable(t).serialize(self()); return self();
}
/** Split serialize() into encode()/decode() */
template <class T> Derived& split(T& t) {
t.decode(self()); return self();
}
};
/** Serialize a type by converting it to/from another type.
* To serialize type Foo by converting to/from type Bar create
* a serializable() overload like this:
*
* SerializeAs<Foo,Bar> serializable(Foo& t) { return SerializeAs<Foo,Bar>(t); }
*/
template <class Type, class AsType>
struct SerializeAs {
Type& value;
SerializeAs(Type & t) : value(t) {}
template <class S> void serialize(S& s) { s.split(*this); }
template <class S> void encode(S& s) const { s(AsType(value)); }
template <class S> void decode(S& s) { AsType x; s(x); value=Type(x); }
};
} // namespace qpid
#endif /*!QPID_SERIALIZER_H*/
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