Repository navigation
Expand file tree
/
Copy pathsinksource.h
More file actions
224 lines (191 loc) · 6.6 KB
/
Copy pathsinksource.h
File metadata and controls
224 lines (191 loc) · 6.6 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
#ifndef UTIL_COMPRESSION_GIPFELI_OPENSOURCE_SINKSOURCE_H_
#define UTIL_COMPRESSION_GIPFELI_OPENSOURCE_SINKSOURCE_H_
// Based on Snappy sink source implementation.
#include <stddef.h>
#include "stubs-internal.h"
using std::min;
namespace util {
namespace compression {
// MemBlock needed for Sink
class MemBlock {
public:
virtual ~MemBlock() { }
void* data() { return data_; }
const void* data() const { return data_; }
size_t length() const { return length_; }
// Original pointer/size passed to constructor (before adjusts)
void* orig_data() { return orig_data_; }
const void* orig_data() const { return orig_data_; }
size_t orig_length() const { return orig_length_; }
// Helper routines to reduce the extent of the visible block. These
// do not affect orig_data/orig_length, so those values can be used
// for appropriate cleanup in the destructors.
//
// It is an error to call these routines with "n > length()".
// Also note, multiple discard operations are cumulative.
// E.g., two calls to "DiscardPrefix(10)" are equivalent to
// one call to "DiscardPrefix(20)".
void DiscardPrefix(size_t n) {
data_ = reinterpret_cast<char*>(data_) + n;
length_ -= n;
}
void DiscardSuffix(size_t n) {
length_ -= n;
}
protected:
// For use by subclasses
MemBlock(void* mem, size_t len) {
data_ = orig_data_ = mem;
length_ = orig_length_ = len;
}
private:
void* data_;
size_t length_;
void* orig_data_;
size_t orig_length_;
DISALLOW_COPY_AND_ASSIGN(MemBlock);
};
// Data block 'space' of specified 'length' must have been created by 'new
// char[]', and it will be delete[]'ed when this object is destroyed.
class NewedMemBlock: public MemBlock {
public:
NewedMemBlock(char* space, size_t len)
: MemBlock(space, len) {
assert(orig_data() != NULL);
}
virtual ~NewedMemBlock() {
delete[] reinterpret_cast<char*>(orig_data());
}
private:
DISALLOW_COPY_AND_ASSIGN(NewedMemBlock);
};
// 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;
// Appends the data from the given MemBlock (see //strings/memblock.h). The
// ByteSink takes ownership of the block, so the given MemBlock must be heap
// allocated. The default implementation calls through to Append(), then
// deletes the given block.
virtual void AppendMemBlock(MemBlock* block) {
Append(reinterpret_cast<char*>(block->data()), block->length());
delete block;
}
// 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* GetAppendBuffer(
size_t min_size, size_t desired_size_hint, char* scratch,
size_t scratch_size, size_t* allocated_size) {
*allocated_size = scratch_size;
return scratch;
}
private:
DISALLOW_COPY_AND_ASSIGN(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;
void CopyTo(Sink* sink, size_t n) {
while (n > 0) {
size_t fragment_size;
const char* fragment_data = Peek(&fragment_size);
if (fragment_size == 0) {
break;
}
fragment_size = min<size_t>(n, fragment_size);
sink->Append(fragment_data, fragment_size);
Skip(fragment_size);
n -= fragment_size;
}
}
private:
DISALLOW_COPY_AND_ASSIGN(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 { return left_; }
virtual const char* Peek(size_t* len) {
*len = left_;
return ptr_;
}
virtual void Skip(size_t n) {
left_ -= n;
ptr_ += 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) {
// Do no copying if the caller filled in the result of GetAppendBuffer()
if (data != dest_) {
memcpy(dest_, data, n);
}
dest_ += n;
}
char* GetAppendBufferVariable(size_t min_size, size_t desired_size_hint,
char* scratch, size_t scratch_size,
size_t* allocated_size) {
*allocated_size = desired_size_hint;
return dest_;
}
private:
char* dest_;
};
} // namespace compression
} // namespace util
#endif // UTIL_COMPRESSION_GIPFELI_OPENSOURCE_SINKSOURCE_H_