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-rw-r--r-- | other-licenses/snappy/src/snappy-sinksource.h | 182 |
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diff --git a/other-licenses/snappy/src/snappy-sinksource.h b/other-licenses/snappy/src/snappy-sinksource.h new file mode 100644 index 0000000000..3c74e1bb6e --- /dev/null +++ b/other-licenses/snappy/src/snappy-sinksource.h @@ -0,0 +1,182 @@ +// 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 THIRD_PARTY_SNAPPY_SNAPPY_SINKSOURCE_H_ +#define THIRD_PARTY_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); + + // For higher performance, Sink implementations can provide custom + // AppendAndTakeOwnership() and GetAppendBufferVariable() methods. + // These methods can reduce the number of copies done during + // compression/decompression. + + // Append "bytes[0,n-1] to the sink. Takes ownership of "bytes" + // and calls the deleter function as (*deleter)(deleter_arg, bytes, n) + // to free the buffer. deleter function must be non NULL. + // + // The default implementation just calls Append and frees "bytes". + // Other implementations may avoid a copy while appending the buffer. + virtual void AppendAndTakeOwnership( + char* bytes, size_t n, void (*deleter)(void*, const char*, size_t), + void *deleter_arg); + + // Returns a writable buffer for appending and writes the buffer's capacity to + // *allocated_size. Guarantees *allocated_size >= min_size. + // May return a pointer to the caller-owned scratch buffer which must have + // scratch_size >= min_size. + // + // The returned buffer is only valid until the next operation + // on this ByteSink. + // + // After writing at most *allocated_size 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 the sink implementation allocates or reallocates an internal buffer, + // it should use the desired_size_hint if appropriate. If a caller cannot + // provide a reasonable guess at the desired capacity, it should set + // desired_size_hint = 0. + // + // If a non-scratch buffer is returned, the caller may only pass + // a prefix to it to Append(). That is, it is not correct to pass an + // interior pointer to Append(). + // + // The default implementation always returns the scratch buffer. + virtual char* GetAppendBufferVariable( + size_t min_size, size_t desired_size_hint, char* scratch, + size_t scratch_size, size_t* allocated_size); + + 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) { } + ~ByteArraySource() override; + size_t Available() const override; + const char* Peek(size_t* len) override; + void Skip(size_t n) override; + 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) { } + ~UncheckedByteArraySink() override; + void Append(const char* data, size_t n) override; + char* GetAppendBuffer(size_t len, char* scratch) override; + char* GetAppendBufferVariable( + size_t min_size, size_t desired_size_hint, char* scratch, + size_t scratch_size, size_t* allocated_size) override; + void AppendAndTakeOwnership( + char* bytes, size_t n, void (*deleter)(void*, const char*, size_t), + void *deleter_arg) override; + + // 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_; +}; + +} // namespace snappy + +#endif // THIRD_PARTY_SNAPPY_SNAPPY_SINKSOURCE_H_ |