michael@0: // Copyright 2011 Google Inc. All Rights Reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: #ifndef UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
michael@0: #define UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
michael@0: 
michael@0: #include <stddef.h>
michael@0: 
michael@0: 
michael@0: namespace snappy {
michael@0: 
michael@0: // A Sink is an interface that consumes a sequence of bytes.
michael@0: class Sink {
michael@0:  public:
michael@0:   Sink() { }
michael@0:   virtual ~Sink();
michael@0: 
michael@0:   // Append "bytes[0,n-1]" to this.
michael@0:   virtual void Append(const char* bytes, size_t n) = 0;
michael@0: 
michael@0:   // Returns a writable buffer of the specified length for appending.
michael@0:   // May return a pointer to the caller-owned scratch buffer which
michael@0:   // must have at least the indicated length.  The returned buffer is
michael@0:   // only valid until the next operation on this Sink.
michael@0:   //
michael@0:   // After writing at most "length" bytes, call Append() with the
michael@0:   // pointer returned from this function and the number of bytes
michael@0:   // written.  Many Append() implementations will avoid copying
michael@0:   // bytes if this function returned an internal buffer.
michael@0:   //
michael@0:   // If a non-scratch buffer is returned, the caller may only pass a
michael@0:   // prefix of it to Append().  That is, it is not correct to pass an
michael@0:   // interior pointer of the returned array to Append().
michael@0:   //
michael@0:   // The default implementation always returns the scratch buffer.
michael@0:   virtual char* GetAppendBuffer(size_t length, char* scratch);
michael@0: 
michael@0:  private:
michael@0:   // No copying
michael@0:   Sink(const Sink&);
michael@0:   void operator=(const Sink&);
michael@0: };
michael@0: 
michael@0: // A Source is an interface that yields a sequence of bytes
michael@0: class Source {
michael@0:  public:
michael@0:   Source() { }
michael@0:   virtual ~Source();
michael@0: 
michael@0:   // Return the number of bytes left to read from the source
michael@0:   virtual size_t Available() const = 0;
michael@0: 
michael@0:   // Peek at the next flat region of the source.  Does not reposition
michael@0:   // the source.  The returned region is empty iff Available()==0.
michael@0:   //
michael@0:   // Returns a pointer to the beginning of the region and store its
michael@0:   // length in *len.
michael@0:   //
michael@0:   // The returned region is valid until the next call to Skip() or
michael@0:   // until this object is destroyed, whichever occurs first.
michael@0:   //
michael@0:   // The returned region may be larger than Available() (for example
michael@0:   // if this ByteSource is a view on a substring of a larger source).
michael@0:   // The caller is responsible for ensuring that it only reads the
michael@0:   // Available() bytes.
michael@0:   virtual const char* Peek(size_t* len) = 0;
michael@0: 
michael@0:   // Skip the next n bytes.  Invalidates any buffer returned by
michael@0:   // a previous call to Peek().
michael@0:   // REQUIRES: Available() >= n
michael@0:   virtual void Skip(size_t n) = 0;
michael@0: 
michael@0:  private:
michael@0:   // No copying
michael@0:   Source(const Source&);
michael@0:   void operator=(const Source&);
michael@0: };
michael@0: 
michael@0: // A Source implementation that yields the contents of a flat array
michael@0: class ByteArraySource : public Source {
michael@0:  public:
michael@0:   ByteArraySource(const char* p, size_t n) : ptr_(p), left_(n) { }
michael@0:   virtual ~ByteArraySource();
michael@0:   virtual size_t Available() const;
michael@0:   virtual const char* Peek(size_t* len);
michael@0:   virtual void Skip(size_t n);
michael@0:  private:
michael@0:   const char* ptr_;
michael@0:   size_t left_;
michael@0: };
michael@0: 
michael@0: // A Sink implementation that writes to a flat array without any bound checks.
michael@0: class UncheckedByteArraySink : public Sink {
michael@0:  public:
michael@0:   explicit UncheckedByteArraySink(char* dest) : dest_(dest) { }
michael@0:   virtual ~UncheckedByteArraySink();
michael@0:   virtual void Append(const char* data, size_t n);
michael@0:   virtual char* GetAppendBuffer(size_t len, char* scratch);
michael@0: 
michael@0:   // Return the current output pointer so that a caller can see how
michael@0:   // many bytes were produced.
michael@0:   // Note: this is not a Sink method.
michael@0:   char* CurrentDestination() const { return dest_; }
michael@0:  private:
michael@0:   char* dest_;
michael@0: };
michael@0: 
michael@0: 
michael@0: }
michael@0: 
michael@0: #endif  // UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_