Implement WebSocketDeflater.

net/websockets/websocket_deflater.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_
+#define NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_
+
+#include <deque>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/net_export.h"
+
+extern "C" struct z_stream_s;
+
+namespace net {
+
+class IOBufferWithSize;
+
+class NET_EXPORT_PRIVATE WebSocketDeflater {
+ public:
+  enum ContextTakeOverMode {
+    DO_NOT_TAKE_OVER_CONTEXT,
+    TAKE_OVER_CONTEXT,
+  };
+
+  explicit WebSocketDeflater(ContextTakeOverMode mode);
+  ~WebSocketDeflater();
+
+  // Returns true if there is no error and false otherwise.
+  // This function must be called exactly once before calling any of
+  // following methods.
+  // |window_bits| must be between 8 and 15 (both inclusive).
+  bool Initialize(int window_bits);
+
+  // Adds bytes to |stream_|.
+  // Returns true if there is no error and false otherwise.
+  bool AddBytes(const char* data, size_t size);
+
+  // Flushes the current processing data.
+  // Returns true if there is no error and false otherwise.
+  bool Finish();
+
+  // Pushes "\x00\x00\xff\xff" to the end of the buffer.
+  void PushSyncMark();
+
+  // Returns the current deflated output.
+  // If the current output is larger than |size| bytes,
+  // returns the first |size| bytes of the current output.
+  // The returned bytes will be dropped from the current output and never be
+  // returned thereafter.
+  scoped_refptr<IOBufferWithSize> GetOutput(size_t size);
+
+  // Returns the size of the current deflated output.
+  size_t CurrentOutputSize() const { return buffer_.size(); }
+
+ private:
+  void ResetContext();
+  int Deflate(int flush);
+
+  scoped_ptr<z_stream_s> stream_;
+  ContextTakeOverMode mode_;
+  std::deque<char> buffer_;
+  std::vector<char> fixed_buffer_;
+  // true if bytes were added after last Finish().
+  bool are_bytes_added_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebSocketDeflater);
+};
+
+}  // namespace net
+
+#endif  // NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_