1 // Copyright 2011 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #include "v8.h" 29 30 #include "scanner-character-streams.h" 31 32 #include "handles.h" 33 #include "unicode-inl.h" 34 35 namespace v8 { 36 namespace internal { 37 38 // ---------------------------------------------------------------------------- 39 // BufferedUtf16CharacterStreams 40 41 BufferedUtf16CharacterStream::BufferedUtf16CharacterStream() 42 : Utf16CharacterStream(), 43 pushback_limit_(NULL) { 44 // Initialize buffer as being empty. First read will fill the buffer. 45 buffer_cursor_ = buffer_; 46 buffer_end_ = buffer_; 47 } 48 49 BufferedUtf16CharacterStream::~BufferedUtf16CharacterStream() { } 50 51 void BufferedUtf16CharacterStream::PushBack(uc32 character) { 52 if (character == kEndOfInput) { 53 pos_--; 54 return; 55 } 56 if (pushback_limit_ == NULL && buffer_cursor_ > buffer_) { 57 // buffer_ is writable, buffer_cursor_ is const pointer. 58 buffer_[--buffer_cursor_ - buffer_] = static_cast<uc16>(character); 59 pos_--; 60 return; 61 } 62 SlowPushBack(static_cast<uc16>(character)); 63 } 64 65 66 void BufferedUtf16CharacterStream::SlowPushBack(uc16 character) { 67 // In pushback mode, the end of the buffer contains pushback, 68 // and the start of the buffer (from buffer start to pushback_limit_) 69 // contains valid data that comes just after the pushback. 70 // We NULL the pushback_limit_ if pushing all the way back to the 71 // start of the buffer. 72 73 if (pushback_limit_ == NULL) { 74 // Enter pushback mode. 75 pushback_limit_ = buffer_end_; 76 buffer_end_ = buffer_ + kBufferSize; 77 buffer_cursor_ = buffer_end_; 78 } 79 // Ensure that there is room for at least one pushback. 80 ASSERT(buffer_cursor_ > buffer_); 81 ASSERT(pos_ > 0); 82 buffer_[--buffer_cursor_ - buffer_] = character; 83 if (buffer_cursor_ == buffer_) { 84 pushback_limit_ = NULL; 85 } else if (buffer_cursor_ < pushback_limit_) { 86 pushback_limit_ = buffer_cursor_; 87 } 88 pos_--; 89 } 90 91 92 bool BufferedUtf16CharacterStream::ReadBlock() { 93 buffer_cursor_ = buffer_; 94 if (pushback_limit_ != NULL) { 95 // Leave pushback mode. 96 buffer_end_ = pushback_limit_; 97 pushback_limit_ = NULL; 98 // If there were any valid characters left at the 99 // start of the buffer, use those. 100 if (buffer_cursor_ < buffer_end_) return true; 101 // Otherwise read a new block. 102 } 103 unsigned length = FillBuffer(pos_, kBufferSize); 104 buffer_end_ = buffer_ + length; 105 return length > 0; 106 } 107 108 109 unsigned BufferedUtf16CharacterStream::SlowSeekForward(unsigned delta) { 110 // Leave pushback mode (i.e., ignore that there might be valid data 111 // in the buffer before the pushback_limit_ point). 112 pushback_limit_ = NULL; 113 return BufferSeekForward(delta); 114 } 115 116 // ---------------------------------------------------------------------------- 117 // GenericStringUtf16CharacterStream 118 119 120 GenericStringUtf16CharacterStream::GenericStringUtf16CharacterStream( 121 Handle<String> data, 122 unsigned start_position, 123 unsigned end_position) 124 : string_(data), 125 length_(end_position) { 126 ASSERT(end_position >= start_position); 127 buffer_cursor_ = buffer_; 128 buffer_end_ = buffer_; 129 pos_ = start_position; 130 } 131 132 133 GenericStringUtf16CharacterStream::~GenericStringUtf16CharacterStream() { } 134 135 136 unsigned GenericStringUtf16CharacterStream::BufferSeekForward(unsigned delta) { 137 unsigned old_pos = pos_; 138 pos_ = Min(pos_ + delta, length_); 139 ReadBlock(); 140 return pos_ - old_pos; 141 } 142 143 144 unsigned GenericStringUtf16CharacterStream::FillBuffer(unsigned from_pos, 145 unsigned length) { 146 if (from_pos >= length_) return 0; 147 if (from_pos + length > length_) { 148 length = length_ - from_pos; 149 } 150 String::WriteToFlat<uc16>(*string_, buffer_, from_pos, from_pos + length); 151 return length; 152 } 153 154 155 // ---------------------------------------------------------------------------- 156 // Utf8ToUtf16CharacterStream 157 Utf8ToUtf16CharacterStream::Utf8ToUtf16CharacterStream(const byte* data, 158 unsigned length) 159 : BufferedUtf16CharacterStream(), 160 raw_data_(data), 161 raw_data_length_(length), 162 raw_data_pos_(0), 163 raw_character_position_(0) { 164 ReadBlock(); 165 } 166 167 168 Utf8ToUtf16CharacterStream::~Utf8ToUtf16CharacterStream() { } 169 170 171 unsigned Utf8ToUtf16CharacterStream::BufferSeekForward(unsigned delta) { 172 unsigned old_pos = pos_; 173 unsigned target_pos = pos_ + delta; 174 SetRawPosition(target_pos); 175 pos_ = raw_character_position_; 176 ReadBlock(); 177 return pos_ - old_pos; 178 } 179 180 181 unsigned Utf8ToUtf16CharacterStream::FillBuffer(unsigned char_position, 182 unsigned length) { 183 static const unibrow::uchar kMaxUtf16Character = 0xffff; 184 SetRawPosition(char_position); 185 if (raw_character_position_ != char_position) { 186 // char_position was not a valid position in the stream (hit the end 187 // while spooling to it). 188 return 0u; 189 } 190 unsigned i = 0; 191 while (i < length - 1) { 192 if (raw_data_pos_ == raw_data_length_) break; 193 unibrow::uchar c = raw_data_[raw_data_pos_]; 194 if (c <= unibrow::Utf8::kMaxOneByteChar) { 195 raw_data_pos_++; 196 } else { 197 c = unibrow::Utf8::CalculateValue(raw_data_ + raw_data_pos_, 198 raw_data_length_ - raw_data_pos_, 199 &raw_data_pos_); 200 } 201 if (c > kMaxUtf16Character) { 202 buffer_[i++] = unibrow::Utf16::LeadSurrogate(c); 203 buffer_[i++] = unibrow::Utf16::TrailSurrogate(c); 204 } else { 205 buffer_[i++] = static_cast<uc16>(c); 206 } 207 } 208 raw_character_position_ = char_position + i; 209 return i; 210 } 211 212 213 static const byte kUtf8MultiByteMask = 0xC0; 214 static const byte kUtf8MultiByteCharStart = 0xC0; 215 static const byte kUtf8MultiByteCharFollower = 0x80; 216 217 218 #ifdef DEBUG 219 static bool IsUtf8MultiCharacterStart(byte first_byte) { 220 return (first_byte & kUtf8MultiByteMask) == kUtf8MultiByteCharStart; 221 } 222 #endif 223 224 225 static bool IsUtf8MultiCharacterFollower(byte later_byte) { 226 return (later_byte & kUtf8MultiByteMask) == kUtf8MultiByteCharFollower; 227 } 228 229 230 // Move the cursor back to point at the preceding UTF-8 character start 231 // in the buffer. 232 static inline void Utf8CharacterBack(const byte* buffer, unsigned* cursor) { 233 byte character = buffer[--*cursor]; 234 if (character > unibrow::Utf8::kMaxOneByteChar) { 235 ASSERT(IsUtf8MultiCharacterFollower(character)); 236 // Last byte of a multi-byte character encoding. Step backwards until 237 // pointing to the first byte of the encoding, recognized by having the 238 // top two bits set. 239 while (IsUtf8MultiCharacterFollower(buffer[--*cursor])) { } 240 ASSERT(IsUtf8MultiCharacterStart(buffer[*cursor])); 241 } 242 } 243 244 245 // Move the cursor forward to point at the next following UTF-8 character start 246 // in the buffer. 247 static inline void Utf8CharacterForward(const byte* buffer, unsigned* cursor) { 248 byte character = buffer[(*cursor)++]; 249 if (character > unibrow::Utf8::kMaxOneByteChar) { 250 // First character of a multi-byte character encoding. 251 // The number of most-significant one-bits determines the length of the 252 // encoding: 253 // 110..... - (0xCx, 0xDx) one additional byte (minimum). 254 // 1110.... - (0xEx) two additional bytes. 255 // 11110... - (0xFx) three additional bytes (maximum). 256 ASSERT(IsUtf8MultiCharacterStart(character)); 257 // Additional bytes is: 258 // 1 if value in range 0xC0 .. 0xDF. 259 // 2 if value in range 0xE0 .. 0xEF. 260 // 3 if value in range 0xF0 .. 0xF7. 261 // Encode that in a single value. 262 unsigned additional_bytes = 263 ((0x3211u) >> (((character - 0xC0) >> 2) & 0xC)) & 0x03; 264 *cursor += additional_bytes; 265 ASSERT(!IsUtf8MultiCharacterFollower(buffer[1 + additional_bytes])); 266 } 267 } 268 269 270 // This can't set a raw position between two surrogate pairs, since there 271 // is no position in the UTF8 stream that corresponds to that. This assumes 272 // that the surrogate pair is correctly coded as a 4 byte UTF-8 sequence. If 273 // it is illegally coded as two 3 byte sequences then there is no problem here. 274 void Utf8ToUtf16CharacterStream::SetRawPosition(unsigned target_position) { 275 if (raw_character_position_ > target_position) { 276 // Spool backwards in utf8 buffer. 277 do { 278 int old_pos = raw_data_pos_; 279 Utf8CharacterBack(raw_data_, &raw_data_pos_); 280 raw_character_position_--; 281 ASSERT(old_pos - raw_data_pos_ <= 4); 282 // Step back over both code units for surrogate pairs. 283 if (old_pos - raw_data_pos_ == 4) raw_character_position_--; 284 } while (raw_character_position_ > target_position); 285 // No surrogate pair splitting. 286 ASSERT(raw_character_position_ == target_position); 287 return; 288 } 289 // Spool forwards in the utf8 buffer. 290 while (raw_character_position_ < target_position) { 291 if (raw_data_pos_ == raw_data_length_) return; 292 int old_pos = raw_data_pos_; 293 Utf8CharacterForward(raw_data_, &raw_data_pos_); 294 raw_character_position_++; 295 ASSERT(raw_data_pos_ - old_pos <= 4); 296 if (raw_data_pos_ - old_pos == 4) raw_character_position_++; 297 } 298 // No surrogate pair splitting. 299 ASSERT(raw_character_position_ == target_position); 300 } 301 302 303 // ---------------------------------------------------------------------------- 304 // ExternalTwoByteStringUtf16CharacterStream 305 306 ExternalTwoByteStringUtf16CharacterStream:: 307 ~ExternalTwoByteStringUtf16CharacterStream() { } 308 309 310 ExternalTwoByteStringUtf16CharacterStream 311 ::ExternalTwoByteStringUtf16CharacterStream( 312 Handle<ExternalTwoByteString> data, 313 int start_position, 314 int end_position) 315 : Utf16CharacterStream(), 316 source_(data), 317 raw_data_(data->GetTwoByteData(start_position)) { 318 buffer_cursor_ = raw_data_, 319 buffer_end_ = raw_data_ + (end_position - start_position); 320 pos_ = start_position; 321 } 322 323 } } // namespace v8::internal 324
