All *WriteStream classes are now part of the same hierarchy:
class BaseWriteStream : ValueObject;
Base class for all *WriteStreams. Provides all the methods from
the old WriteStream except for buffer() and SetPosition()
(relegated to NonStreamingWriteStreams). Has one pure virtual
method Realloc that must be overridden by concrete subclasses.
class NonStreamingWriteStream : BaseWriteStream;
Base class for all *WriteStreams where the entire stream is available
at all times (i.e., no flushing to an external sink). Extends the
public BaseWriteStream API with buffer() (for accessing the stream
contents) and SetPosition() (for changing the current stream pointer
to the given absolute position in the stream).
class MallocWriteStream : NonStreamingWriteStream;
Uses realloc to reallocate the internal buffer. Almost the same as
the old WriteStream, except that it only takes an initial size. Adds
one public method Steal() for taking ownership of the current buffer
contents (after which the buffer is reset to an empty state). Instead
of passing a pointer to a buffer, the internal buffer must be accessed
via either Steal() or buffer(), which allows access to the current
stream contents without changing ownership or resetting the stream.
The internal buffer is freed on stream destruction.
class ZoneWriteStream: NonStreamingWriteStream;
Takes a zone and reallocates the internal buffer in that zone. No
additional public methods beyond those available from
NonStreamingWriteStream.
class StreamingWriteStream : BaseWriteStream;
Uses realloc to reallocate the internal buffer. Generally same as
before, where the contents of the stream are periodically flushed
using Dart_StreamingWriteCallback. Since it extends BaseWriteStream,
there are now more methods available for writing data to the stream
than just Print/VPrint/WriteBytes. Since portions of the stream may be
flushed and thus no longer in the internal buffer, does not provide
access to the contents of the stream or a way to reposition the
current stream pointer. Flushes any unflushed data and frees the
internal buffer on stream destruction.
Also refactor things so that write streams are passed to appropriate
recipients, instead of the recipients taking arguments they only used to
create a WriteStream internally. Thus, recipients now can just specify
the appropriate base class for the public API used:
* BaseWriteStream for just writing to the stream, or
* NonStreamingWriteStream if re-positioning or the stream contents are
needed.
Change-Id: I419096ecd9331483d168b079fca55b69ef397f15
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164080
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Tess Strickland
a4a714ebf9