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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_