/*
* Copyright (C) 2010 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
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* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CachedMetadata_h
#define CachedMetadata_h
#include "wtf/Forward.h"
#include "wtf/RefCounted.h"
#include "wtf/Vector.h"
namespace WebCore {
// Metadata retrieved from the embedding application's cache.
//
// Serialized data is NOT portable across architectures. However, reading the
// data type ID will reject data generated with a different byte-order.
class CachedMetadata : public RefCounted<CachedMetadata> {
public:
static PassRefPtr<CachedMetadata> create(unsigned dataTypeID, const char* data, size_t size)
{
return adoptRef(new CachedMetadata(dataTypeID, data, size));
}
static PassRefPtr<CachedMetadata> deserialize(const char* data, size_t size)
{
return adoptRef(new CachedMetadata(data, size));
}
const Vector<char>& serialize() const
{
return m_serializedData;
}
~CachedMetadata() { }
unsigned dataTypeID() const
{
return readUnsigned(dataTypeIDStart);
}
const char* data() const
{
if (m_serializedData.size() < dataStart)
return 0;
return m_serializedData.data() + dataStart;
}
size_t size() const
{
if (m_serializedData.size() < dataStart)
return 0;
return m_serializedData.size() - dataStart;
}
private:
// Reads an unsigned value at position. Returns 0 on error.
unsigned readUnsigned(size_t position) const
{
if (m_serializedData.size() < position + sizeof(unsigned))
return 0;
return *reinterpret_cast_ptr<unsigned*>(const_cast<char*>(m_serializedData.data() + position));
}
// Appends an unsigned value to the end of the serialized data.
void appendUnsigned(unsigned value)
{
m_serializedData.append(reinterpret_cast<const char*>(&value), sizeof(unsigned));
}
CachedMetadata(const char* data, size_t size)
{
// Serialized metadata should have non-empty data.
ASSERT(size > dataStart);
m_serializedData.append(data, size);
}
CachedMetadata(unsigned dataTypeID, const char* data, size_t size)
{
// Don't allow an ID of 0, it is used internally to indicate errors.
ASSERT(dataTypeID);
ASSERT(data);
appendUnsigned(dataTypeID);
m_serializedData.append(data, size);
}
// Serialization offsets. Format: [DATA_TYPE_ID][DATA].
static const size_t dataTypeIDStart = 0;
static const size_t dataStart = sizeof(unsigned);
// Since the serialization format supports random access, storing it in
// serialized form avoids need for a copy during serialization.
Vector<char> m_serializedData;
};
}
#endif