Implement WebSocketDeflater.

net/websockets/websocket_deflater.h

Index: net/websockets/websocket_deflater.h
diff --git a/net/websockets/websocket_deflater.h b/net/websockets/websocket_deflater.h
new file mode 100644
index 0000000000000000000000000000000000000000..9b4018e100fda730f6a3db2de97fa191d223a1c1
--- /dev/null
+++ b/net/websockets/websocket_deflater.h
@@ -0,0 +1,63 @@
+// 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 <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/net_export.h"
+#include "third_party/zlib/zlib.h"
+
+namespace net {
+
+class IOBufferWithSize;
+
+class NET_EXPORT_PRIVATE WebSocketDeflater {
+ public:
+  enum ContextTakeOverMode {
+    DO_NOT_TAKE_OVER_CONTEXT,
+    TAKE_OVER_CONTEXT,
+  };
+
+  // |window_bits| must be between 8 and 15 (both inclusive).
+  WebSocketDeflater(int window_bits, ContextTakeOverMode mode);
+  ~WebSocketDeflater();
+
+  // Adds bytes to |stream_|.
+  // Returns true if there is no error and false otherwise.
+  bool AddBytes(const char* data, size_t size);
+
+  // Flushes and returns deflated result.

[Adam Rice, 2013/09/05 06:05:59]

Remove the "and returns".

[yhirano, 2013/09/05 06:34:07]

Thanks, done.

+  // Returns true if there is no error and false otherwise.
+  bool Finish();
+
+  // 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);

[Adam Rice, 2013/09/05 06:05:59]

A minor issue is that if the size() of the return value is equal to |size|, the
caller will have to call CurrentOutputSize() to determine whether there is still
output remaining or if the output was coincidentally exactly |size| bytes. Maybe
this is good enough.

+
+  // Returns the size of the current deflated output.
+  size_t CurrentOutputSize();

[Adam Rice, 2013/09/05 06:05:59]

This can probably be a const method.

[yhirano, 2013/09/05 06:34:07]

Done.

+
+ private:
+  void Reset();
+  int Deflate(size_t size, int flush);
+
+  scoped_ptr<z_stream> stream_;
+  ContextTakeOverMode mode_;
+  std::vector<char> buffer_;

[Adam Rice, 2013/09/05 06:05:59]

Something like std::queue<std::vector<char> > might be better, so you can free
data you have already returned from GetOutput() without doing expensive copies.

[yhirano, 2013/09/05 06:34:07]

Done.

+  bool are_bytes_added_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebSocketDeflater);
+};
+
+}  // namespace net
+
+#endif  // NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_