Introduce (private) ZLibFilter to dart:io.

runtime/bin/filter.h

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef BIN_FILTER_H_
+#define BIN_FILTER_H_
+
+#include "bin/builtin.h"
+#include "bin/utils.h"
+
+#include "third_party/zlib/zlib.h"
+
+class Filter {
+ protected:
+  Filter() {}
+
+ public:
+  virtual ~Filter() {}
+
+ public:
+  virtual bool Init() = 0;
+  /**
+   * On a succesfull call to Process, Process will take ownership of data.
+   */
+  virtual bool Process(uint8_t* data, intptr_t length) = 0;
+  virtual intptr_t Processed(uint8_t* buffer, intptr_t length, bool finish) = 0;
+
+
+ public:
+  static Dart_Handle SetFilterPointerNativeField(Dart_Handle filter,
+                                                 Filter* filter_pointer);
+  static Dart_Handle GetFilterPointerNativeField(Dart_Handle filter,
+                                                 Filter** filter_pointer);
+};
+
+class ZLibDeflateFilter : public Filter {
+ public:
+  ZLibDeflateFilter(bool gZip = false, int level = 6)
+    : gZip(gZip), level(level), current_buffer(NULL) {}
+  virtual ~ZLibDeflateFilter();
+
+ public:
+  virtual bool Init();
+  virtual bool Process(uint8_t* data, intptr_t length);
+  virtual intptr_t Processed(uint8_t* buffer, intptr_t length, bool finish);
+
+ private:
+  const bool gZip;
+  const int level;
+  uint8_t* current_buffer;
+  z_stream stream;
+};
+
+class ZLibInflateFilter : public Filter {
+ public:
+  ZLibInflateFilter() : current_buffer(NULL) {}
+  virtual ~ZLibInflateFilter();
+
+ public:
+  virtual bool Init();
+  virtual bool Process(uint8_t* data, intptr_t length);
+  virtual intptr_t Processed(uint8_t* buffer, intptr_t length, bool finish);
+
+ private:
+  uint8_t* current_buffer;
+  z_stream stream;
+};
+
+#endif  // BIN_FILTER_H_
+