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// Protocol Buffers - Google's data interchange format
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// Copyright 2008 Google Inc. All rights reserved.
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// http://code.google.com/p/protobuf/
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Author: kenton@google.com (Kenton Varda)
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// Based on original Protocol Buffers design by
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// Sanjay Ghemawat, Jeff Dean, and others.
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// This file contains common implementations of the interfaces defined in
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// zero_copy_stream.h which are included in the "lite" protobuf library.
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// These implementations cover I/O on raw arrays and strings, as well as
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// adaptors which make it easy to implement streams based on traditional
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// streams. Of course, many users will probably want to write their own
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// implementations of these interfaces specific to the particular I/O
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// abstractions they prefer to use, but these should cover the most common
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#ifndef GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_LITE_H__
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#define GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_LITE_H__
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#include <google/protobuf/io/zero_copy_stream.h>
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#include <google/protobuf/stubs/common.h>
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// ===================================================================
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// A ZeroCopyInputStream backed by an in-memory array of bytes.
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class LIBPROTOBUF_EXPORT ArrayInputStream : public ZeroCopyInputStream {
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// Create an InputStream that returns the bytes pointed to by "data".
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// "data" remains the property of the caller but must remain valid until
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// the stream is destroyed. If a block_size is given, calls to Next()
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// will return data blocks no larger than the given size. Otherwise, the
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// first call to Next() returns the entire array. block_size is mainly
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// useful for testing; in production you would probably never want to set
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ArrayInputStream(const void* data, int size, int block_size = -1);
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// implements ZeroCopyInputStream ----------------------------------
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bool Next(const void** data, int* size);
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void BackUp(int count);
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int64 ByteCount() const;
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const uint8* const data_; // The byte array.
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const int size_; // Total size of the array.
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const int block_size_; // How many bytes to return at a time.
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int last_returned_size_; // How many bytes we returned last time Next()
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// was called (used for error checking only).
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GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ArrayInputStream);
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// ===================================================================
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// A ZeroCopyOutputStream backed by an in-memory array of bytes.
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class LIBPROTOBUF_EXPORT ArrayOutputStream : public ZeroCopyOutputStream {
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// Create an OutputStream that writes to the bytes pointed to by "data".
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// "data" remains the property of the caller but must remain valid until
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// the stream is destroyed. If a block_size is given, calls to Next()
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// will return data blocks no larger than the given size. Otherwise, the
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// first call to Next() returns the entire array. block_size is mainly
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// useful for testing; in production you would probably never want to set
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ArrayOutputStream(void* data, int size, int block_size = -1);
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~ArrayOutputStream();
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// implements ZeroCopyOutputStream ---------------------------------
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bool Next(void** data, int* size);
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void BackUp(int count);
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int64 ByteCount() const;
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uint8* const data_; // The byte array.
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const int size_; // Total size of the array.
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const int block_size_; // How many bytes to return at a time.
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int last_returned_size_; // How many bytes we returned last time Next()
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// was called (used for error checking only).
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GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ArrayOutputStream);
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// ===================================================================
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// A ZeroCopyOutputStream which appends bytes to a string.
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class LIBPROTOBUF_EXPORT StringOutputStream : public ZeroCopyOutputStream {
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// Create a StringOutputStream which appends bytes to the given string.
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// The string remains property of the caller, but it MUST NOT be accessed
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// in any way until the stream is destroyed.
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// Hint: If you call target->reserve(n) before creating the stream,
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// the first call to Next() will return at least n bytes of buffer
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explicit StringOutputStream(string* target);
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~StringOutputStream();
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// implements ZeroCopyOutputStream ---------------------------------
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bool Next(void** data, int* size);
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void BackUp(int count);
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int64 ByteCount() const;
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static const int kMinimumSize = 16;
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GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(StringOutputStream);
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// Note: There is no StringInputStream. Instead, just create an
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// ArrayInputStream as follows:
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// ArrayInputStream input(str.data(), str.size());
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// ===================================================================
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// A generic traditional input stream interface.
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// Lots of traditional input streams (e.g. file descriptors, C stdio
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// streams, and C++ iostreams) expose an interface where every read
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// involves copying bytes into a buffer. If you want to take such an
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// interface and make a ZeroCopyInputStream based on it, simply implement
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// CopyingInputStream and then use CopyingInputStreamAdaptor.
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// CopyingInputStream implementations should avoid buffering if possible.
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// CopyingInputStreamAdaptor does its own buffering and will read data
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class LIBPROTOBUF_EXPORT CopyingInputStream {
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virtual ~CopyingInputStream();
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// Reads up to "size" bytes into the given buffer. Returns the number of
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// bytes read. Read() waits until at least one byte is available, or
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// returns zero if no bytes will ever become available (EOF), or -1 if a
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// permanent read error occurred.
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virtual int Read(void* buffer, int size) = 0;
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// Skips the next "count" bytes of input. Returns the number of bytes
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// actually skipped. This will always be exactly equal to "count" unless
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// EOF was reached or a permanent read error occurred.
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// The default implementation just repeatedly calls Read() into a scratch
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virtual int Skip(int count);
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// A ZeroCopyInputStream which reads from a CopyingInputStream. This is
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// useful for implementing ZeroCopyInputStreams that read from traditional
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// streams. Note that this class is not really zero-copy.
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// If you want to read from file descriptors or C++ istreams, this is
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// already implemented for you: use FileInputStream or IstreamInputStream
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class LIBPROTOBUF_EXPORT CopyingInputStreamAdaptor : public ZeroCopyInputStream {
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// Creates a stream that reads from the given CopyingInputStream.
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// If a block_size is given, it specifies the number of bytes that
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// should be read and returned with each call to Next(). Otherwise,
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// a reasonable default is used. The caller retains ownership of
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// copying_stream unless SetOwnsCopyingStream(true) is called.
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explicit CopyingInputStreamAdaptor(CopyingInputStream* copying_stream,
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int block_size = -1);
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~CopyingInputStreamAdaptor();
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// Call SetOwnsCopyingStream(true) to tell the CopyingInputStreamAdaptor to
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// delete the underlying CopyingInputStream when it is destroyed.
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void SetOwnsCopyingStream(bool value) { owns_copying_stream_ = value; }
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// implements ZeroCopyInputStream ----------------------------------
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bool Next(const void** data, int* size);
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void BackUp(int count);
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bool Skip(int count);
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int64 ByteCount() const;
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// Insures that buffer_ is not NULL.
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void AllocateBufferIfNeeded();
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// Frees the buffer and resets buffer_used_.
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// The underlying copying stream.
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CopyingInputStream* copying_stream_;
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bool owns_copying_stream_;
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// True if we have seen a permenant error from the underlying stream.
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// The current position of copying_stream_, relative to the point where
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// we started reading.
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// Data is read into this buffer. It may be NULL if no buffer is currently
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// in use. Otherwise, it points to an array of size buffer_size_.
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scoped_array<uint8> buffer_;
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const int buffer_size_;
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// Number of valid bytes currently in the buffer (i.e. the size last
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// returned by Next()). 0 <= buffer_used_ <= buffer_size_.
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// Number of bytes in the buffer which were backed up over by a call to
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// BackUp(). These need to be returned again.
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// 0 <= backup_bytes_ <= buffer_used_
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GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingInputStreamAdaptor);
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// ===================================================================
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// A generic traditional output stream interface.
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// Lots of traditional output streams (e.g. file descriptors, C stdio
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// streams, and C++ iostreams) expose an interface where every write
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// involves copying bytes from a buffer. If you want to take such an
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// interface and make a ZeroCopyOutputStream based on it, simply implement
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// CopyingOutputStream and then use CopyingOutputStreamAdaptor.
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// CopyingOutputStream implementations should avoid buffering if possible.
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// CopyingOutputStreamAdaptor does its own buffering and will write data
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class LIBPROTOBUF_EXPORT CopyingOutputStream {
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virtual ~CopyingOutputStream();
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// Writes "size" bytes from the given buffer to the output. Returns true
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// if successful, false on a write error.
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virtual bool Write(const void* buffer, int size) = 0;
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// A ZeroCopyOutputStream which writes to a CopyingOutputStream. This is
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// useful for implementing ZeroCopyOutputStreams that write to traditional
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// streams. Note that this class is not really zero-copy.
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// If you want to write to file descriptors or C++ ostreams, this is
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// already implemented for you: use FileOutputStream or OstreamOutputStream
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class LIBPROTOBUF_EXPORT CopyingOutputStreamAdaptor : public ZeroCopyOutputStream {
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// Creates a stream that writes to the given Unix file descriptor.
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// If a block_size is given, it specifies the size of the buffers
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// that should be returned by Next(). Otherwise, a reasonable default
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explicit CopyingOutputStreamAdaptor(CopyingOutputStream* copying_stream,
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int block_size = -1);
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~CopyingOutputStreamAdaptor();
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// Writes all pending data to the underlying stream. Returns false if a
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// write error occurred on the underlying stream. (The underlying
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// stream itself is not necessarily flushed.)
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// Call SetOwnsCopyingStream(true) to tell the CopyingOutputStreamAdaptor to
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// delete the underlying CopyingOutputStream when it is destroyed.
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void SetOwnsCopyingStream(bool value) { owns_copying_stream_ = value; }
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// implements ZeroCopyOutputStream ---------------------------------
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bool Next(void** data, int* size);
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void BackUp(int count);
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int64 ByteCount() const;
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// Write the current buffer, if it is present.
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// Insures that buffer_ is not NULL.
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void AllocateBufferIfNeeded();
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// The underlying copying stream.
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CopyingOutputStream* copying_stream_;
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bool owns_copying_stream_;
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// True if we have seen a permenant error from the underlying stream.
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// The current position of copying_stream_, relative to the point where
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// we started writing.
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// Data is written from this buffer. It may be NULL if no buffer is
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// currently in use. Otherwise, it points to an array of size buffer_size_.
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scoped_array<uint8> buffer_;
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const int buffer_size_;
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// Number of valid bytes currently in the buffer (i.e. the size last
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// returned by Next()). When BackUp() is called, we just reduce this.
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// 0 <= buffer_used_ <= buffer_size_.
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GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CopyingOutputStreamAdaptor);
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// ===================================================================
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} // namespace protobuf
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} // namespace google
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#endif // GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_LITE_H__
added
removed
src/google/protobuf/io/zero_copy_stream_impl_lite.h
