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29 #ifndef UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
30 #define UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
37 // A Sink is an interface that consumes a sequence of bytes.
43 // Append "bytes[0,n-1]" to this.
44 virtual void Append(const char* bytes, size_t n) = 0;
46 // Returns a writable buffer of the specified length for appending.
47 // May return a pointer to the caller-owned scratch buffer which
48 // must have at least the indicated length. The returned buffer is
49 // only valid until the next operation on this Sink.
51 // After writing at most "length" bytes, call Append() with the
52 // pointer returned from this function and the number of bytes
53 // written. Many Append() implementations will avoid copying
54 // bytes if this function returned an internal buffer.
56 // If a non-scratch buffer is returned, the caller may only pass a
57 // prefix of it to Append(). That is, it is not correct to pass an
58 // interior pointer of the returned array to Append().
60 // The default implementation always returns the scratch buffer.
61 virtual char* GetAppendBuffer(size_t length, char* scratch);
66 void operator=(const Sink&);
69 // A Source is an interface that yields a sequence of bytes
75 // Return the number of bytes left to read from the source
76 virtual size_t Available() const = 0;
78 // Peek at the next flat region of the source. Does not reposition
79 // the source. The returned region is empty iff Available()==0.
81 // Returns a pointer to the beginning of the region and store its
84 // The returned region is valid until the next call to Skip() or
85 // until this object is destroyed, whichever occurs first.
87 // The returned region may be larger than Available() (for example
88 // if this ByteSource is a view on a substring of a larger source).
89 // The caller is responsible for ensuring that it only reads the
91 virtual const char* Peek(size_t* len) = 0;
93 // Skip the next n bytes. Invalidates any buffer returned by
94 // a previous call to Peek().
95 // REQUIRES: Available() >= n
96 virtual void Skip(size_t n) = 0;
100 Source(const Source&);
101 void operator=(const Source&);
104 // A Source implementation that yields the contents of a flat array
105 class ByteArraySource : public Source {
107 ByteArraySource(const char* p, size_t n) : ptr_(p), left_(n) { }
108 virtual ~ByteArraySource();
109 virtual size_t Available() const;
110 virtual const char* Peek(size_t* len);
111 virtual void Skip(size_t n);
117 // A Sink implementation that writes to a flat array without any bound checks.
118 class UncheckedByteArraySink : public Sink {
120 explicit UncheckedByteArraySink(char* dest) : dest_(dest) { }
121 virtual ~UncheckedByteArraySink();
122 virtual void Append(const char* data, size_t n);
123 virtual char* GetAppendBuffer(size_t len, char* scratch);
125 // Return the current output pointer so that a caller can see how
126 // many bytes were produced.
127 // Note: this is not a Sink method.
128 char* CurrentDestination() const { return dest_; }
136 #endif // UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_