Hide implementation details: SkFrontBufferedStream

include/utils/SkFrontBufferedStream.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
-#include "SkStream.h"
-#include "SkTemplates.h"
+#include "SkTypes.h"
+
+class SkStream;
+class SkStreamRewindable;
 
 /**
  *  Specialized stream that only buffers the first X bytes of a stream,
  *  where X is passed in by the user. Note that unlike some buffered
  *  stream APIs, once more than those bytes are read, no more buffering
  *  is done. This stream is designed for a use case where the caller
  *  knows that rewind will only be called from within X bytes (inclusive),
  *  and the wrapped stream is not necessarily able to rewind at all.
  */
-class SkFrontBufferedStream : public SkStreamRewindable {
+class SkFrontBufferedStream {
 public:
     /**
      *  Creates a new stream that wraps and buffers SkStream.
      *  @param stream SkStream to buffer. If NULL, NULL is returned. After

[reed1, 2013/11/12 17:41:02]

Not sure the punctuation is correct in the 2nd/3rd sentences.

1. Does it really mean that if we fail to create a bufferstream, that we have
somehow 'ruined' the base stream?

2. Do we *promise" to buffer exactly bufferSize? Can we buffer more or less?

3. What if we fail to allocate the requested buffer? Does that mean the caller
should unref their stream?

[scroggo, 2013/11/12 19:46:54]

I don't see the punctuation error. "If NULL, NULL is returned" could be
clarified though. Updated.
It should not (though at the moment, the only way for failure is if there is no
input stream, or if we throw). Updated the comments.
There's probably no reason to put an upper bound on what will be buffered, but
this should be the minimum. Updated the comments.
We throw.

      *      this call, unref stream and do not refer to it.
      *      SkFrontBufferedStream is expected to be its only owner.
      *  @param bufferSize Exact size of the buffer to be used.
      *  @return An SkStream that can buffer up to bufferSize.
      */
     static SkStreamRewindable* Create(SkStream* stream, size_t bufferSize);
-
-    virtual size_t read(void* buffer, size_t size) SK_OVERRIDE;
-
-    virtual bool isAtEnd() const SK_OVERRIDE;
-
-    virtual bool rewind() SK_OVERRIDE;
-
-    virtual bool hasPosition() const SK_OVERRIDE { return true; }
-
-    virtual size_t getPosition() const SK_OVERRIDE { return fOffset; }
-
-    virtual bool hasLength() const SK_OVERRIDE;
-
-    virtual size_t getLength() const SK_OVERRIDE;
-
-    virtual SkStreamRewindable* duplicate() const SK_OVERRIDE { return NULL; }
-
-private:
-    SkAutoTUnref<SkStream>  fStream;
-    // Current offset into the stream. Always >= 0.
-    size_t                  fOffset;
-    // Amount that has been buffered by calls to read. Will always be less than
-    // fBufferSize.
-    size_t                  fBufferedSoFar;
-    // Total size of the buffer.
-    const size_t            fBufferSize;
-    SkAutoTMalloc<char>     fBuffer;
-
-    // Private. Use Create.
-    SkFrontBufferedStream(SkStream*, size_t bufferSize);
-
-    // Read up to size bytes from already buffered data, and copy to
-    // dst, if non-NULL. Updates fOffset. Assumes that fOffset is less
-    // than fBufferedSoFar.
-    size_t readFromBuffer(char* dst, size_t size);
-
-    // Buffer up to size bytes from the stream, and copy to dst if non-
-    // NULL. Updates fOffset and fBufferedSoFar. Assumes that fOffset is
-    // less than fBufferedSoFar, and size is greater than 0.
-    size_t bufferAndWriteTo(char* dst, size_t size);
-
-    // Read up to size bytes directly from the stream and into dst if non-
-    // NULL. Updates fOffset. Assumes fOffset is at or beyond the buffered
-    // data, and size is greater than 0.
-    size_t readDirectlyFromStream(char* dst, size_t size);
-
-    typedef SkStream INHERITED;
 };