1 : // Copyright 2011 Google Inc. All Rights Reserved.
2 : //
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4 : // modification, are permitted provided that the following conditions are
5 : // met:
6 : //
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8 : // notice, this list of conditions and the following disclaimer.
9 : // * Redistributions in binary form must reproduce the above
10 : // copyright notice, this list of conditions and the following disclaimer
11 : // in the documentation and/or other materials provided with the
12 : // distribution.
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15 : // this software without specific prior written permission.
16 : //
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21 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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23 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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27 : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 :
29 : #ifndef UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
30 : #define UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
31 :
32 : #include <stddef.h>
33 :
34 :
35 : namespace snappy {
36 :
37 : // A Sink is an interface that consumes a sequence of bytes.
38 : class Sink {
39 : public:
40 1837 : Sink() { }
41 : virtual ~Sink();
42 :
43 : // Append "bytes[0,n-1]" to this.
44 : virtual void Append(const char* bytes, size_t n) = 0;
45 :
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.
50 : //
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.
55 : //
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().
59 : //
60 : // The default implementation always returns the scratch buffer.
61 : virtual char* GetAppendBuffer(size_t length, char* scratch);
62 :
63 : private:
64 : // No copying
65 : Sink(const Sink&);
66 : void operator=(const Sink&);
67 : };
68 :
69 : // A Source is an interface that yields a sequence of bytes
70 : class Source {
71 : public:
72 3807 : Source() { }
73 : virtual ~Source();
74 :
75 : // Return the number of bytes left to read from the source
76 : virtual size_t Available() const = 0;
77 :
78 : // Peek at the next flat region of the source. Does not reposition
79 : // the source. The returned region is empty iff Available()==0.
80 : //
81 : // Returns a pointer to the beginning of the region and store its
82 : // length in *len.
83 : //
84 : // The returned region is valid until the next call to Skip() or
85 : // until this object is destroyed, whichever occurs first.
86 : //
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
90 : // Available() bytes.
91 : virtual const char* Peek(size_t* len) = 0;
92 :
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;
97 :
98 : private:
99 : // No copying
100 : Source(const Source&);
101 : void operator=(const Source&);
102 : };
103 :
104 : // A Source implementation that yields the contents of a flat array
105 : class ByteArraySource : public Source {
106 : public:
107 3807 : 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);
112 : private:
113 : const char* ptr_;
114 : size_t left_;
115 : };
116 :
117 : // A Sink implementation that writes to a flat array without any bound checks.
118 : class UncheckedByteArraySink : public Sink {
119 : public:
120 1837 : 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);
124 :
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 1837 : char* CurrentDestination() const { return dest_; }
129 : private:
130 : char* dest_;
131 : };
132 :
133 :
134 : }
135 :
136 : #endif // UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
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