scanner.cc revision 69a99ed0b2b2ef69d393c371b03db3a98aaf880e
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 "ast.h" 31#include "handles.h" 32#include "scanner.h" 33#include "unicode-inl.h" 34 35namespace v8 { 36namespace internal { 37 38// ---------------------------------------------------------------------------- 39// BufferedUC16CharacterStreams 40 41BufferedUC16CharacterStream::BufferedUC16CharacterStream() 42 : UC16CharacterStream(), 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 49BufferedUC16CharacterStream::~BufferedUC16CharacterStream() { } 50 51void BufferedUC16CharacterStream::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 66void BufferedUC16CharacterStream::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 92bool BufferedUC16CharacterStream::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 109unsigned BufferedUC16CharacterStream::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// GenericStringUC16CharacterStream 118 119 120GenericStringUC16CharacterStream::GenericStringUC16CharacterStream( 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 133GenericStringUC16CharacterStream::~GenericStringUC16CharacterStream() { } 134 135 136unsigned GenericStringUC16CharacterStream::BufferSeekForward(unsigned delta) { 137 unsigned old_pos = pos_; 138 pos_ = Min(pos_ + delta, length_); 139 ReadBlock(); 140 return pos_ - old_pos; 141} 142 143 144unsigned GenericStringUC16CharacterStream::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// Utf8ToUC16CharacterStream 157Utf8ToUC16CharacterStream::Utf8ToUC16CharacterStream(const byte* data, 158 unsigned length) 159 : BufferedUC16CharacterStream(), 160 raw_data_(data), 161 raw_data_length_(length), 162 raw_data_pos_(0), 163 raw_character_position_(0) { 164 ReadBlock(); 165} 166 167 168Utf8ToUC16CharacterStream::~Utf8ToUC16CharacterStream() { } 169 170 171unsigned Utf8ToUC16CharacterStream::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 181unsigned Utf8ToUC16CharacterStream::FillBuffer(unsigned char_position, 182 unsigned length) { 183 static const unibrow::uchar kMaxUC16Character = 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) { 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 // Don't allow characters outside of the BMP. 201 if (c > kMaxUC16Character) { 202 c = unibrow::Utf8::kBadChar; 203 } 204 } 205 buffer_[i++] = static_cast<uc16>(c); 206 } 207 raw_character_position_ = char_position + i; 208 return i; 209} 210 211 212static const byte kUtf8MultiByteMask = 0xC0; 213static const byte kUtf8MultiByteCharStart = 0xC0; 214static const byte kUtf8MultiByteCharFollower = 0x80; 215 216 217#ifdef DEBUG 218static bool IsUtf8MultiCharacterStart(byte first_byte) { 219 return (first_byte & kUtf8MultiByteMask) == kUtf8MultiByteCharStart; 220} 221#endif 222 223 224static bool IsUtf8MultiCharacterFollower(byte later_byte) { 225 return (later_byte & kUtf8MultiByteMask) == kUtf8MultiByteCharFollower; 226} 227 228 229// Move the cursor back to point at the preceding UTF-8 character start 230// in the buffer. 231static inline void Utf8CharacterBack(const byte* buffer, unsigned* cursor) { 232 byte character = buffer[--*cursor]; 233 if (character > unibrow::Utf8::kMaxOneByteChar) { 234 ASSERT(IsUtf8MultiCharacterFollower(character)); 235 // Last byte of a multi-byte character encoding. Step backwards until 236 // pointing to the first byte of the encoding, recognized by having the 237 // top two bits set. 238 while (IsUtf8MultiCharacterFollower(buffer[--*cursor])) { } 239 ASSERT(IsUtf8MultiCharacterStart(buffer[*cursor])); 240 } 241} 242 243 244// Move the cursor forward to point at the next following UTF-8 character start 245// in the buffer. 246static inline void Utf8CharacterForward(const byte* buffer, unsigned* cursor) { 247 byte character = buffer[(*cursor)++]; 248 if (character > unibrow::Utf8::kMaxOneByteChar) { 249 // First character of a multi-byte character encoding. 250 // The number of most-significant one-bits determines the length of the 251 // encoding: 252 // 110..... - (0xCx, 0xDx) one additional byte (minimum). 253 // 1110.... - (0xEx) two additional bytes. 254 // 11110... - (0xFx) three additional bytes (maximum). 255 ASSERT(IsUtf8MultiCharacterStart(character)); 256 // Additional bytes is: 257 // 1 if value in range 0xC0 .. 0xDF. 258 // 2 if value in range 0xE0 .. 0xEF. 259 // 3 if value in range 0xF0 .. 0xF7. 260 // Encode that in a single value. 261 unsigned additional_bytes = 262 ((0x3211u) >> (((character - 0xC0) >> 2) & 0xC)) & 0x03; 263 *cursor += additional_bytes; 264 ASSERT(!IsUtf8MultiCharacterFollower(buffer[1 + additional_bytes])); 265 } 266} 267 268 269void Utf8ToUC16CharacterStream::SetRawPosition(unsigned target_position) { 270 if (raw_character_position_ > target_position) { 271 // Spool backwards in utf8 buffer. 272 do { 273 Utf8CharacterBack(raw_data_, &raw_data_pos_); 274 raw_character_position_--; 275 } while (raw_character_position_ > target_position); 276 return; 277 } 278 // Spool forwards in the utf8 buffer. 279 while (raw_character_position_ < target_position) { 280 if (raw_data_pos_ == raw_data_length_) return; 281 Utf8CharacterForward(raw_data_, &raw_data_pos_); 282 raw_character_position_++; 283 } 284} 285 286 287// ---------------------------------------------------------------------------- 288// ExternalTwoByteStringUC16CharacterStream 289 290ExternalTwoByteStringUC16CharacterStream:: 291 ~ExternalTwoByteStringUC16CharacterStream() { } 292 293 294ExternalTwoByteStringUC16CharacterStream 295 ::ExternalTwoByteStringUC16CharacterStream( 296 Handle<ExternalTwoByteString> data, 297 int start_position, 298 int end_position) 299 : UC16CharacterStream(), 300 source_(data), 301 raw_data_(data->GetTwoByteData(start_position)) { 302 buffer_cursor_ = raw_data_, 303 buffer_end_ = raw_data_ + (end_position - start_position); 304 pos_ = start_position; 305} 306 307 308// ---------------------------------------------------------------------------- 309// Scanner::LiteralScope 310 311Scanner::LiteralScope::LiteralScope(Scanner* self) 312 : scanner_(self), complete_(false) { 313 self->StartLiteral(); 314} 315 316 317Scanner::LiteralScope::~LiteralScope() { 318 if (!complete_) scanner_->DropLiteral(); 319} 320 321 322void Scanner::LiteralScope::Complete() { 323 scanner_->TerminateLiteral(); 324 complete_ = true; 325} 326 327} } // namespace v8::internal 328