diff -r 000000000000 -r 6474c204b198 js/src/vm/Compression.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/vm/Compression.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef vm_Compression_h
+#define vm_Compression_h
+
+#ifdef USE_ZLIB
+
+#include <zlib.h>
+
+#include "jstypes.h"
+
+namespace js {
+
+class Compressor
+{
+    /* Number of bytes we should hand to zlib each compressMore() call. */
+    static const size_t CHUNKSIZE = 2048;
+    z_stream zs;
+    const unsigned char *inp;
+    size_t inplen;
+    size_t outbytes;
+    bool initialized;
+
+  public:
+    enum Status {
+        MOREOUTPUT,
+        DONE,
+        CONTINUE,
+        OOM
+    };
+
+    Compressor(const unsigned char *inp, size_t inplen);
+    ~Compressor();
+    bool init();
+    void setOutput(unsigned char *out, size_t outlen);
+    size_t outWritten() const { return outbytes; }
+    /* Compress some of the input. Return true if it should be called again. */
+    Status compressMore();
+};
+
+/*
+ * Decompress a string. The caller must know the length of the output and
+ * allocate |out| to a string of that length.
+ */
+bool DecompressString(const unsigned char *inp, size_t inplen,
+                      unsigned char *out, size_t outlen);
+
+} /* namespace js */
+
+#endif /* USE_ZLIB */
+#endif /* vm_Compression_h */