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31 #ifndef CachedMetadata_h
32 #define CachedMetadata_h
34 #include <wtf/RefCounted.h>
35 #include <wtf/Vector.h>
39 // Metadata retrieved from the embedding application's cache.
41 // Serialized data is NOT portable across architectures. However, reading the
42 // data type ID will reject data generated with a different byte-order.
43 class CachedMetadata : public RefCounted<CachedMetadata> {
45 static PassRefPtr<CachedMetadata> create(unsigned dataTypeID, const char* data, size_t size)
47 return adoptRef(new CachedMetadata(dataTypeID, data, size));
50 static PassRefPtr<CachedMetadata> deserialize(const char* data, size_t size)
52 return adoptRef(new CachedMetadata(data, size));
55 const Vector<char>& serialize() const
57 return m_serializedData;
62 unsigned dataTypeID() const
64 return readUnsigned(dataTypeIDStart);
67 const char* data() const
69 if (m_serializedData.size() < dataStart)
71 return m_serializedData.data() + dataStart;
76 if (m_serializedData.size() < dataStart)
78 return m_serializedData.size() - dataStart;
82 // Reads an unsigned value at position. Returns 0 on error.
83 unsigned readUnsigned(size_t position) const
85 if (m_serializedData.size() < position + sizeof(unsigned))
87 return *reinterpret_cast_ptr<unsigned*>(const_cast<char*>(m_serializedData.data() + position));
90 // Appends an unsigned value to the end of the serialized data.
91 void appendUnsigned(unsigned value)
93 m_serializedData.append(reinterpret_cast<const char*>(&value), sizeof(unsigned));
96 CachedMetadata(const char* data, size_t size)
98 // Serialized metadata should have non-empty data.
99 ASSERT(size > dataStart);
101 m_serializedData.append(data, size);
104 CachedMetadata(unsigned dataTypeID, const char* data, size_t size)
106 // Don't allow an ID of 0, it is used internally to indicate errors.
110 appendUnsigned(dataTypeID);
111 m_serializedData.append(data, size);
114 // Serialization offsets. Format: [DATA_TYPE_ID][DATA].
115 static const size_t dataTypeIDStart = 0;
116 static const size_t dataStart = sizeof(unsigned);
118 // Since the serialization format supports random access, storing it in
119 // serialized form avoids need for a copy during serialization.
120 Vector<char> m_serializedData;