xgboost

base64.h
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1
8 #ifndef XGBOOST_COMMON_BASE64_H_
9 #define XGBOOST_COMMON_BASE64_H_
10
11 #include <xgboost/logging.h>
12 #include <cctype>
13 #include <cstdio>
14 #include <string>
15 #include "./io.h"
16
17 namespace xgboost {
18 namespace common {
20 class StreamBufferReader {
21 public:
22 explicit StreamBufferReader(size_t buffer_size)
23 :stream_(NULL),
24 read_len_(1), read_ptr_(1) {
25 buffer_.resize(buffer_size);
26 }
30 inline void set_stream(dmlc::Stream *stream) {
31 stream_ = stream;
32 read_len_ = read_ptr_ = 1;
33 }
37 inline char GetChar(void) {
38 while (true) {
39 if (read_ptr_ < read_len_) {
40 return buffer_[read_ptr_++];
41 } else {
42 read_len_ = stream_->Read(&buffer_[0], buffer_.length());
43 if (read_len_ == 0) return EOF;
44 read_ptr_ = 0;
45 }
46 }
47 }
49 inline bool AtEnd(void) const {
50 return read_len_ == 0;
51 }
52
53 private:
55 dmlc::Stream *stream_;
57 std::string buffer_;
59 size_t read_len_;
61 size_t read_ptr_;
62 };
63
65 namespace base64 {
66 const char DecodeTable[] = {
67 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
68 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
69 62, // '+'
70 0, 0, 0,
71 63, // '/'
72 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // '0'-'9'
73 0, 0, 0, 0, 0, 0, 0,
74 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
75 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 'A'-'Z'
76 0, 0, 0, 0, 0, 0,
77 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
78 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // 'a'-'z'
79 };
80 static const char EncodeTable[] =
81 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
82 } // namespace base64
84 class Base64InStream: public dmlc::Stream {
85 public:
86 explicit Base64InStream(dmlc::Stream *fs) : reader_(256) {
87 reader_.set_stream(fs);
88 num_prev = 0; tmp_ch = 0;
89 }
94 inline void InitPosition(void) {
95 // get a character
96 do {
97 tmp_ch = reader_.GetChar();
98 } while (isspace(tmp_ch));
99 }
101 inline bool IsEOF(void) const {
102 return num_prev == 0 && (tmp_ch == EOF || isspace(tmp_ch));
103 }
104 virtual size_t Read(void *ptr, size_t size) {
105 using base64::DecodeTable;
106 if (size == 0) return 0;
107 // use tlen to record left size
108 size_t tlen = size;
109 unsigned char *cptr = static_cast<unsigned char*>(ptr);
110 // if anything left, load from previous buffered result
111 if (num_prev != 0) {
112 if (num_prev == 2) {
113 if (tlen >= 2) {
114 *cptr++ = buf_prev[0];
115 *cptr++ = buf_prev[1];
116 tlen -= 2;
117 num_prev = 0;
118 } else {
119 // assert tlen == 1
120 *cptr++ = buf_prev[0]; --tlen;
121 buf_prev[0] = buf_prev[1];
122 num_prev = 1;
123 }
124 } else {
125 // assert num_prev == 1
126 *cptr++ = buf_prev[0]; --tlen; num_prev = 0;
127 }
128 }
129 if (tlen == 0) return size;
130 int nvalue;
131 // note: everything goes with 4 bytes in Base64
132 // so we process 4 bytes a unit
133 while (tlen && tmp_ch != EOF && !isspace(tmp_ch)) {
134 // first byte
135 nvalue = DecodeTable[tmp_ch] << 18;
136 {
137 // second byte
138 tmp_ch = reader_.GetChar();
139 CHECK(tmp_ch != EOF && !isspace(tmp_ch)) << "invalid base64 format";
140 nvalue |= DecodeTable[tmp_ch] << 12;
141 *cptr++ = (nvalue >> 16) & 0xFF; --tlen;
142 }
143 {
144 // third byte
145 tmp_ch = reader_.GetChar();
146 CHECK(tmp_ch != EOF && !isspace(tmp_ch)) << "invalid base64 format";
147 // handle termination
148 if (tmp_ch == '=') {
149 tmp_ch = reader_.GetChar();
150 CHECK(tmp_ch == '=') << "invalid base64 format";
151 tmp_ch = reader_.GetChar();
152 CHECK(tmp_ch == EOF || isspace(tmp_ch))
153 << "invalid base64 format";
154 break;
155 }
156 nvalue |= DecodeTable[tmp_ch] << 6;
157 if (tlen) {
158 *cptr++ = (nvalue >> 8) & 0xFF; --tlen;
159 } else {
160 buf_prev[num_prev++] = (nvalue >> 8) & 0xFF;
161 }
162 }
163 {
164 // fourth byte
165 tmp_ch = reader_.GetChar();
166 CHECK(tmp_ch != EOF && !isspace(tmp_ch))
167 << "invalid base64 format";
168 if (tmp_ch == '=') {
169 tmp_ch = reader_.GetChar();
170 CHECK(tmp_ch == EOF || isspace(tmp_ch))
171 << "invalid base64 format";
172 break;
173 }
174 nvalue |= DecodeTable[tmp_ch];
175 if (tlen) {
176 *cptr++ = nvalue & 0xFF; --tlen;
177 } else {
178 buf_prev[num_prev ++] = nvalue & 0xFF;
179 }
180 }
181 // get next char
182 tmp_ch = reader_.GetChar();
183 }
184 if (kStrictCheck) {
185 CHECK_EQ(tlen, 0) << "Base64InStream: read incomplete";
186 }
187 return size - tlen;
188 }
189 virtual void Write(const void *ptr, size_t size) {
190 LOG(FATAL) << "Base64InStream do not support write";
191 }
192
193 private:
194 StreamBufferReader reader_;
195 int tmp_ch;
196 int num_prev;
197 unsigned char buf_prev[2];
198 // whether we need to do strict check
199 static const bool kStrictCheck = false;
200 };
202 class Base64OutStream: public dmlc::Stream {
203 public:
204 explicit Base64OutStream(dmlc::Stream *fp) : fp(fp) {
205 buf_top = 0;
206 }
207 virtual void Write(const void *ptr, size_t size) {
208 using base64::EncodeTable;
209 size_t tlen = size;
210 const unsigned char *cptr = static_cast<const unsigned char*>(ptr);
211 while (tlen) {
212 while (buf_top < 3 && tlen != 0) {
213 buf[++buf_top] = *cptr++; --tlen;
214 }
215 if (buf_top == 3) {
216 // flush 4 bytes out
217 PutChar(EncodeTable[buf[1] >> 2]);
218 PutChar(EncodeTable[((buf[1] << 4) | (buf[2] >> 4)) & 0x3F]);
219 PutChar(EncodeTable[((buf[2] << 2) | (buf[3] >> 6)) & 0x3F]);
220 PutChar(EncodeTable[buf[3] & 0x3F]);
221 buf_top = 0;
222 }
223 }
224 }
225 virtual size_t Read(void *ptr, size_t size) {
226 LOG(FATAL) << "Base64OutStream do not support read";
227 return 0;
228 }
233 inline void Finish(char endch = EOF) {
234 using base64::EncodeTable;
235 if (buf_top == 1) {
236 PutChar(EncodeTable[buf[1] >> 2]);
237 PutChar(EncodeTable[(buf[1] << 4) & 0x3F]);
238 PutChar('=');
239 PutChar('=');
240 }
241 if (buf_top == 2) {
242 PutChar(EncodeTable[buf[1] >> 2]);
243 PutChar(EncodeTable[((buf[1] << 4) | (buf[2] >> 4)) & 0x3F]);
244 PutChar(EncodeTable[(buf[2] << 2) & 0x3F]);
245 PutChar('=');
246 }
247 buf_top = 0;
248 if (endch != EOF) PutChar(endch);
249 this->Flush();
250 }
251
252 private:
253 dmlc::Stream *fp;
254 int buf_top;
255 unsigned char buf[4];
256 std::string out_buf;
257 static const size_t kBufferSize = 256;
258
259 inline void PutChar(char ch) {
260 out_buf += ch;
261 if (out_buf.length() >= kBufferSize) Flush();
262 }
263 inline void Flush(void) {
264 if (out_buf.length() != 0) {
265 fp->Write(&out_buf[0], out_buf.length());
266 out_buf.clear();
267 }
268 }
269 };
270 } // namespace common
271 } // namespace xgboost
272 #endif // XGBOOST_COMMON_BASE64_H_
xgboost::common::StreamBufferReader
buffer reader of the stream that allows you to get
Definition: base64.h:20
xgboost::common::base64::DecodeTable
const char DecodeTable[]
Definition: base64.h:66
xgboost::common::StreamBufferReader::AtEnd
bool AtEnd(void) const
whether we are reaching the end of file
Definition: base64.h:49
xgboost::common::StreamBufferReader::GetChar
char GetChar(void)
allows quick read using get char
Definition: base64.h:37
xgboost::common::Base64InStream::Read
virtual size_t Read(void *ptr, size_t size)
Definition: base64.h:104
io.h
general stream interface for serialization, I/O
xgboost::common::Base64OutStream::Finish
void Finish(char endch=EOF)
finish writing of all current base64 stream, do some post processing
Definition: base64.h:233
xgboost::common::StreamBufferReader::set_stream
void set_stream(dmlc::Stream *stream)
set input stream
Definition: base64.h:30
xgboost::common::Base64OutStream
the stream that write to base64, note we take from file pointers
Definition: base64.h:202
xgboost::common::Base64InStream
the stream that reads from base64, note we take from file pointers
Definition: base64.h:84
xgboost::common::Base64OutStream::Base64OutStream
Base64OutStream(dmlc::Stream *fp)
Definition: base64.h:204
xgboost::common::Base64InStream::InitPosition
void InitPosition(void)
initialize the stream position to beginning of next base64 stream call this function before actually ...
Definition: base64.h:94
xgboost
namespace of xgboost
Definition: base.h:102
xgboost::common::Base64OutStream::Write
virtual void Write(const void *ptr, size_t size)
Definition: base64.h:207
xgboost::common::Base64InStream::Base64InStream
Base64InStream(dmlc::Stream *fs)
Definition: base64.h:86
xgboost::common::Base64InStream::IsEOF
bool IsEOF(void) const
whether current position is end of a base64 stream
Definition: base64.h:101
xgboost::common::Base64OutStream::Read
virtual size_t Read(void *ptr, size_t size)
Definition: base64.h:225
xgboost::common::Base64InStream::Write
virtual void Write(const void *ptr, size_t size)
Definition: base64.h:189
xgboost::common::StreamBufferReader::StreamBufferReader
StreamBufferReader(size_t buffer_size)
Definition: base64.h:22