Implement basic classes for HPACK (HTTP/2 compression)

net/spdy/hpack_header_table.h

+#ifndef NET_SPDY_HPACK_HEADER_TABLE_H_
+#define NET_SPDY_HPACK_HEADER_TABLE_H_
+
+#include <cstddef>
+#include <deque>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/macros.h"
+#include "net/spdy/hpack_entry.h"
+
+namespace net {
+
+// All section references below are to
+// http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-04
+// .
+
+// A data structure for both the header table (described in 3.1.2) and
+// the reference set (3.1.3). This structure also keeps track of how
+// many times a header has been 'touched', which is useful for both
+// encoding and decoding.
+class HpackHeaderTable {
+ public:
+  HpackHeaderTable();
+
+  ~HpackHeaderTable();
+
+  uint32 size() const { return size_; }
+  uint32 max_size() const { return max_size_; }
+
+  // Returns the total number of entries.
+  uint32 GetEntryCount() const;
+
+  // The given index must be >= 0 and < GetEntryCount().
+  const HpackEntry& GetEntry(uint32 index) const;
+
+  // The given index must be >= 0 and < GetEntryCount().
+  HpackEntry* GetMutableEntry(uint32 index);
+
+  // Sets the maximum size of the header table, evicting entries if
+  // necessary as described in 3.3.2.
+  void SetMaxSize(uint32 max_size);
+
+  // The given entry must not be one from the header table, since it
+  // may get evicted. Tries to add the given entry to the header
+  // table, evicting entries if necessary as described in 3.3.3. index
+  // will be filled in with the index of the added entry, or -1 if the
+  // entry could not be added. removed_referenced_indices will be
+  // filled in with the indices of any removed entries that were in
+  // the reference set.
+  void TryAddEntry(const HpackEntry& entry,
+                   int32* index,
+                   std::vector<uint32>* removed_referenced_indices);
+
+ private:
+  std::deque<HpackEntry> entries_;
+  uint32 size_;
+  uint32 max_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(HpackHeaderTable);
+};
+
+}  // namespace net
+
+#endif  // NET_SPDY_HPACK_HEADER_TABLE_H_