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 // Copyright 2011 Google Inc. All Rights Reserved.

 //

 // Redistribution and use in source and binary forms, with or without

 // modification, are permitted provided that the following conditions are

 // met:

 //

 //     * Redistributions of source code must retain the above copyright

 // notice, this list of conditions and the following disclaimer.

 //     * Redistributions in binary form must reproduce the above

 // copyright notice, this list of conditions and the following disclaimer

 // in the documentation and/or other materials provided with the

 // distribution.

 //     * Neither the name of Google Inc. nor the names of its

 // contributors may be used to endorse or promote products derived from

 // this software without specific prior written permission.

 //

 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #ifndef UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_

 #define UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_

 #include <stddef.h>

 namespace snappy {

 // A Sink is an interface that consumes a sequence of bytes.

 class Sink {

  public:

   Sink() { }

   virtual ~Sink();

   // Append "bytes[0,n-1]" to this.

   virtual void Append(const char* bytes, size_t n) = 0;

   // Returns a writable buffer of the specified length for appending.

   // May return a pointer to the caller-owned scratch buffer which

   // must have at least the indicated length.  The returned buffer is

   // only valid until the next operation on this Sink.

   //

   // After writing at most "length" bytes, call Append() with the

   // pointer returned from this function and the number of bytes

   // written.  Many Append() implementations will avoid copying

   // bytes if this function returned an internal buffer.

   //

   // If a non-scratch buffer is returned, the caller may only pass a

   // prefix of it to Append().  That is, it is not correct to pass an

   // interior pointer of the returned array to Append().

   //

   // The default implementation always returns the scratch buffer.

   virtual char* GetAppendBuffer(size_t length, char* scratch);

  private:

   // No copying

   Sink(const Sink&);

   void operator=(const Sink&);

 };

 // A Source is an interface that yields a sequence of bytes

 class Source {

  public:

   Source() { }

   virtual ~Source();

   // Return the number of bytes left to read from the source

   virtual size_t Available() const = 0;

   // Peek at the next flat region of the source.  Does not reposition

   // the source.  The returned region is empty iff Available()==0.

   //

   // Returns a pointer to the beginning of the region and store its

   // length in *len.

   //

   // The returned region is valid until the next call to Skip() or

   // until this object is destroyed, whichever occurs first.

   //

   // The returned region may be larger than Available() (for example

   // if this ByteSource is a view on a substring of a larger source).

   // The caller is responsible for ensuring that it only reads the

   // Available() bytes.

   virtual const char* Peek(size_t* len) = 0;

   // Skip the next n bytes.  Invalidates any buffer returned by

   // a previous call to Peek().

   // REQUIRES: Available() >= n

   virtual void Skip(size_t n) = 0;

  private:

   // No copying

   Source(const Source&);

   void operator=(const Source&);

 };

 // A Source implementation that yields the contents of a flat array

 class ByteArraySource : public Source {

  public:

   ByteArraySource(const char* p, size_t n) : ptr_(p), left_(n) { }

   virtual ~ByteArraySource();

   virtual size_t Available() const;

   virtual const char* Peek(size_t* len);

   virtual void Skip(size_t n);

  private:

   const char* ptr_;

   size_t left_;

 };

 // A Sink implementation that writes to a flat array without any bound checks.

 class UncheckedByteArraySink : public Sink {

  public:

   explicit UncheckedByteArraySink(char* dest) : dest_(dest) { }

   virtual ~UncheckedByteArraySink();

   virtual void Append(const char* data, size_t n);

   virtual char* GetAppendBuffer(size_t len, char* scratch);

   // Return the current output pointer so that a caller can see how

   // many bytes were produced.

   // Note: this is not a Sink method.

   char* CurrentDestination() const { return dest_; }

  private:

   char* dest_;

 };

 }

 #endif  // UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_