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1 : // Copyright 2011 Google Inc. All Rights Reserved.
2 : //
3 : // Redistribution and use in source and binary forms, with or without
4 : // modification, are permitted provided that the following conditions are
5 : // met:
6 : //
7 : // * Redistributions of source code must retain the above copyright
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.
13 : // * Neither the name of Google Inc. nor the names of its
14 : // contributors may be used to endorse or promote products derived from
15 : // this software without specific prior written permission.
16 : //
17 : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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 74 : 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 :
64 : private:
65 : // No copying
66 : explicit Sink(const Sink&);
67 : void operator=(const Sink&);
68 : };
69 :
70 : // A Source is an interface that yields a sequence of bytes
71 : class Source {
72 : public:
73 148 : Source() { }
74 : virtual ~Source();
75 :
76 : // Return the number of bytes left to read from the source
77 : virtual size_t Available() const = 0;
78 :
79 : // Peek at the next flat region of the source. Does not reposition
80 : // the source. The returned region is empty iff Available()==0.
81 : //
82 : // Returns a pointer to the beginning of the region and store its
83 : // length in *len.
84 : //
85 : // The returned region is valid until the next call to Skip() or
86 : // until this object is destroyed, whichever occurs first.
87 : //
88 : // The returned region may be larger than Available() (for example
89 : // if this ByteSource is a view on a substring of a larger source).
90 : // The caller is responsible for ensuring that it only reads the
91 : // Available() bytes.
92 : virtual const char* Peek(size_t* len) = 0;
93 :
94 : // Skip the next n bytes. Invalidates any buffer returned by
95 : // a previous call to Peek().
96 : // REQUIRES: Available() >= n
97 : virtual void Skip(size_t n) = 0;
98 :
99 : private:
100 : // No copying
101 : explicit Source(const Source&);
102 : void operator=(const Source&);
103 : };
104 :
105 : // A Source implementation that yields the contents of a flat array
106 : class ByteArraySource : public Source {
107 : public:
108 148 : ByteArraySource(const char* p, size_t n) : ptr_(p), left_(n) { }
109 : virtual ~ByteArraySource();
110 : virtual size_t Available() const;
111 : virtual const char* Peek(size_t* len);
112 : virtual void Skip(size_t n);
113 : private:
114 : const char* ptr_;
115 : size_t left_;
116 : };
117 :
118 : // A Sink implementation that writes to a flat array without any bound checks.
119 : class UncheckedByteArraySink : public Sink {
120 : public:
121 74 : explicit UncheckedByteArraySink(char* dest) : dest_(dest) { }
122 : virtual ~UncheckedByteArraySink();
123 : virtual void Append(const char* data, size_t n);
124 : virtual char* GetAppendBuffer(size_t len, char* scratch);
125 :
126 : // Return the current output pointer so that a caller can see how
127 : // many bytes were produced.
128 : // Note: this is not a Sink method.
129 74 : char* CurrentDestination() const { return dest_; }
130 : private:
131 : char* dest_;
132 : };
133 :
134 :
135 : }
136 :
137 : #endif // UTIL_SNAPPY_SNAPPY_SINKSOURCE_H_
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