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#ifndef QPID_FRAMING_BUFFERTYPES_H
#define QPID_FRAMING_BUFFERTYPES_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.
*
*/
/**@file
* Using templates with framing::Buffer is difficultg becase of the many
* different put/get function names. Here we define a set of types
* corresponding the basic types of Buffer but presenting a uniform
* encode/decode/encodedSize interface.
*
* It also provides some convenience templates for the common case of
* encoding a single encodable value as a string, e.g.
*
* LongString ls("hello");
* std::string encoded = encodeStr(ls);
* LongString ls2 = decodeStr<LongString>(encoded);
* LongString ls3;
* decodeStr(encoded, ls3);
*/
namespace qpid {
namespace framing {
// Templates to help define types
template <class ValueType> struct BufferTypeTraits {
typedef void (Buffer::*Put)(const ValueType&);
typedef void (Buffer::*Get)(ValueType&);
};
template <class ValueType,
typename BufferTypeTraits<ValueType>::Put PutFn,
typename BufferTypeTraits<ValueType>::Get GetFn>
struct EncodeDecodeTemplate {
EncodeDecodeTemplate(const ValueType& s) : value(s) {}
operator ValueType() const { return value; }
ValueType value;
void encode(framing::Buffer& buf) const { (buf.*PutFn)(value); }
void decode(framing::Buffer& buf) { (buf.*GetFn)(value); }
};
template <size_t Size,
typename BufferTypeTraits<std::string>::Put PutFn,
typename BufferTypeTraits<std::string>::Get GetFn
>
struct StringTypeTemplate : public EncodeDecodeTemplate<std::string, PutFn, GetFn> {
typedef EncodeDecodeTemplate<std::string, PutFn, GetFn> Base;
StringTypeTemplate(const std::string& s) : Base(s) {}
size_t encodedSize() const { return Size + Base::value.size(); }
};
// Convenience tempates for encoding/decoding values to/from a std::string.
/** Encode value as a string. */
template <class T> std::string encodeStr(const T& value) {
std::string encoded(value.encodedSize(), '\0');
framing::Buffer buffer(&encoded[0], encoded.size());
value.encode(buffer);
return encoded;
}
/** Decode value from a string. */
template <class T> void decodeStr(const std::string& encoded, T& value) {
framing::Buffer b(const_cast<char*>(&encoded[0]), encoded.size());
value.decode(b);
}
/** Decode value from a string. */
template <class T> T decodeStr(const std::string& encoded) {
T value;
decodeStr(encoded, value);
return value;
}
// The types
typedef StringTypeTemplate<4, &Buffer::putLongString, &Buffer::getLongString> LongString;
typedef StringTypeTemplate<2, &Buffer::putMediumString, &Buffer::getMediumString> MediumString;
typedef StringTypeTemplate<1, &Buffer::putShortString, &Buffer::getShortString> ShortString;
// TODO aconway 2013-07-26: Add integer types.
}} // namespace qpid::framing
#endif /*!QPID_FRAMING_BUFFERTYPES_H*/
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