Lexer.h revision 6e2901407bff59aeb4cc301cc58b034723d0eb49
1//===--- Lexer.h - C Language Family Lexer ----------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the Lexer interface. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_CLANG_LEXER_H 15#define LLVM_CLANG_LEXER_H 16 17#include "clang/Lex/PreprocessorLexer.h" 18#include "clang/Basic/LangOptions.h" 19#include "llvm/ADT/SmallVector.h" 20#include <string> 21#include <vector> 22#include <cassert> 23 24namespace clang { 25class Diagnostic; 26class SourceManager; 27class Preprocessor; 28class DiagnosticBuilder; 29 30/// Lexer - This provides a simple interface that turns a text buffer into a 31/// stream of tokens. This provides no support for file reading or buffering, 32/// or buffering/seeking of tokens, only forward lexing is supported. It relies 33/// on the specified Preprocessor object to handle preprocessor directives, etc. 34class Lexer : public PreprocessorLexer { 35 //===--------------------------------------------------------------------===// 36 // Constant configuration values for this lexer. 37 const char *BufferStart; // Start of the buffer. 38 const char *BufferEnd; // End of the buffer. 39 SourceLocation FileLoc; // Location for start of file. 40 LangOptions Features; // Features enabled by this language (cache). 41 bool Is_PragmaLexer; // True if lexer for _Pragma handling. 42 bool IsEofCodeCompletion; // True if EOF is treated as a code-completion. 43 44 //===--------------------------------------------------------------------===// 45 // Context-specific lexing flags set by the preprocessor. 46 // 47 48 /// ExtendedTokenMode - The lexer can optionally keep comments and whitespace 49 /// and return them as tokens. This is used for -C and -CC modes, and 50 /// whitespace preservation can be useful for some clients that want to lex 51 /// the file in raw mode and get every character from the file. 52 /// 53 /// When this is set to 2 it returns comments and whitespace. When set to 1 54 /// it returns comments, when it is set to 0 it returns normal tokens only. 55 unsigned char ExtendedTokenMode; 56 57 //===--------------------------------------------------------------------===// 58 // Context that changes as the file is lexed. 59 // NOTE: any state that mutates when in raw mode must have save/restore code 60 // in Lexer::isNextPPTokenLParen. 61 62 // BufferPtr - Current pointer into the buffer. This is the next character 63 // to be lexed. 64 const char *BufferPtr; 65 66 // IsAtStartOfLine - True if the next lexed token should get the "start of 67 // line" flag set on it. 68 bool IsAtStartOfLine; 69 70 Lexer(const Lexer&); // DO NOT IMPLEMENT 71 void operator=(const Lexer&); // DO NOT IMPLEMENT 72 friend class Preprocessor; 73 74 void InitLexer(const char *BufStart, const char *BufPtr, const char *BufEnd); 75public: 76 77 /// Lexer constructor - Create a new lexer object for the specified buffer 78 /// with the specified preprocessor managing the lexing process. This lexer 79 /// assumes that the associated file buffer and Preprocessor objects will 80 /// outlive it, so it doesn't take ownership of either of them. 81 Lexer(FileID FID, const llvm::MemoryBuffer *InputBuffer, Preprocessor &PP); 82 83 /// Lexer constructor - Create a new raw lexer object. This object is only 84 /// suitable for calls to 'LexRawToken'. This lexer assumes that the text 85 /// range will outlive it, so it doesn't take ownership of it. 86 Lexer(SourceLocation FileLoc, const LangOptions &Features, 87 const char *BufStart, const char *BufPtr, const char *BufEnd); 88 89 /// Lexer constructor - Create a new raw lexer object. This object is only 90 /// suitable for calls to 'LexRawToken'. This lexer assumes that the text 91 /// range will outlive it, so it doesn't take ownership of it. 92 Lexer(FileID FID, const llvm::MemoryBuffer *InputBuffer, 93 const SourceManager &SM, const LangOptions &Features); 94 95 /// Create_PragmaLexer: Lexer constructor - Create a new lexer object for 96 /// _Pragma expansion. This has a variety of magic semantics that this method 97 /// sets up. It returns a new'd Lexer that must be delete'd when done. 98 static Lexer *Create_PragmaLexer(SourceLocation SpellingLoc, 99 SourceLocation InstantiationLocStart, 100 SourceLocation InstantiationLocEnd, 101 unsigned TokLen, Preprocessor &PP); 102 103 104 /// getFeatures - Return the language features currently enabled. NOTE: this 105 /// lexer modifies features as a file is parsed! 106 const LangOptions &getFeatures() const { return Features; } 107 108 /// getFileLoc - Return the File Location for the file we are lexing out of. 109 /// The physical location encodes the location where the characters come from, 110 /// the virtual location encodes where we should *claim* the characters came 111 /// from. Currently this is only used by _Pragma handling. 112 SourceLocation getFileLoc() const { return FileLoc; } 113 114 /// Lex - Return the next token in the file. If this is the end of file, it 115 /// return the tok::eof token. Return true if an error occurred and 116 /// compilation should terminate, false if normal. This implicitly involves 117 /// the preprocessor. 118 void Lex(Token &Result) { 119 // Start a new token. 120 Result.startToken(); 121 122 // NOTE, any changes here should also change code after calls to 123 // Preprocessor::HandleDirective 124 if (IsAtStartOfLine) { 125 Result.setFlag(Token::StartOfLine); 126 IsAtStartOfLine = false; 127 } 128 129 // Get a token. Note that this may delete the current lexer if the end of 130 // file is reached. 131 LexTokenInternal(Result); 132 } 133 134 /// isPragmaLexer - Returns true if this Lexer is being used to lex a pragma. 135 bool isPragmaLexer() const { return Is_PragmaLexer; } 136 137 /// IndirectLex - An indirect call to 'Lex' that can be invoked via 138 /// the PreprocessorLexer interface. 139 void IndirectLex(Token &Result) { Lex(Result); } 140 141 /// LexFromRawLexer - Lex a token from a designated raw lexer (one with no 142 /// associated preprocessor object. Return true if the 'next character to 143 /// read' pointer points at the end of the lexer buffer, false otherwise. 144 bool LexFromRawLexer(Token &Result) { 145 assert(LexingRawMode && "Not already in raw mode!"); 146 Lex(Result); 147 // Note that lexing to the end of the buffer doesn't implicitly delete the 148 // lexer when in raw mode. 149 return BufferPtr == BufferEnd; 150 } 151 152 /// isKeepWhitespaceMode - Return true if the lexer should return tokens for 153 /// every character in the file, including whitespace and comments. This 154 /// should only be used in raw mode, as the preprocessor is not prepared to 155 /// deal with the excess tokens. 156 bool isKeepWhitespaceMode() const { 157 return ExtendedTokenMode > 1; 158 } 159 160 /// SetKeepWhitespaceMode - This method lets clients enable or disable 161 /// whitespace retention mode. 162 void SetKeepWhitespaceMode(bool Val) { 163 assert((!Val || LexingRawMode) && 164 "Can only enable whitespace retention in raw mode"); 165 ExtendedTokenMode = Val ? 2 : 0; 166 } 167 168 /// inKeepCommentMode - Return true if the lexer should return comments as 169 /// tokens. 170 bool inKeepCommentMode() const { 171 return ExtendedTokenMode > 0; 172 } 173 174 /// SetCommentRetentionMode - Change the comment retention mode of the lexer 175 /// to the specified mode. This is really only useful when lexing in raw 176 /// mode, because otherwise the lexer needs to manage this. 177 void SetCommentRetentionState(bool Mode) { 178 assert(!isKeepWhitespaceMode() && 179 "Can't play with comment retention state when retaining whitespace"); 180 ExtendedTokenMode = Mode ? 1 : 0; 181 } 182 183 /// \brief Specify that end-of-file is to be considered a code-completion 184 /// token. 185 /// 186 /// When in this mode, the end-of-file token will be immediately preceded 187 /// by a code-completion token. 188 void SetEofIsCodeCompletion(bool Val = true) { 189 IsEofCodeCompletion = Val; 190 } 191 192 const char *getBufferStart() const { return BufferStart; } 193 194 /// ReadToEndOfLine - Read the rest of the current preprocessor line as an 195 /// uninterpreted string. This switches the lexer out of directive mode. 196 std::string ReadToEndOfLine(); 197 198 199 /// Diag - Forwarding function for diagnostics. This translate a source 200 /// position in the current buffer into a SourceLocation object for rendering. 201 DiagnosticBuilder Diag(const char *Loc, unsigned DiagID) const; 202 203 /// getSourceLocation - Return a source location identifier for the specified 204 /// offset in the current file. 205 SourceLocation getSourceLocation(const char *Loc, unsigned TokLen = 1) const; 206 207 /// getSourceLocation - Return a source location for the next character in 208 /// the current file. 209 SourceLocation getSourceLocation() { return getSourceLocation(BufferPtr); } 210 211 /// Stringify - Convert the specified string into a C string by escaping '\' 212 /// and " characters. This does not add surrounding ""'s to the string. 213 /// If Charify is true, this escapes the ' character instead of ". 214 static std::string Stringify(const std::string &Str, bool Charify = false); 215 216 /// Stringify - Convert the specified string into a C string by escaping '\' 217 /// and " characters. This does not add surrounding ""'s to the string. 218 static void Stringify(llvm::SmallVectorImpl<char> &Str); 219 220 /// MeasureTokenLength - Relex the token at the specified location and return 221 /// its length in bytes in the input file. If the token needs cleaning (e.g. 222 /// includes a trigraph or an escaped newline) then this count includes bytes 223 /// that are part of that. 224 static unsigned MeasureTokenLength(SourceLocation Loc, 225 const SourceManager &SM, 226 const LangOptions &LangOpts); 227 228 //===--------------------------------------------------------------------===// 229 // Internal implementation interfaces. 230private: 231 232 /// LexTokenInternal - Internal interface to lex a preprocessing token. Called 233 /// by Lex. 234 /// 235 void LexTokenInternal(Token &Result); 236 237 /// FormTokenWithChars - When we lex a token, we have identified a span 238 /// starting at BufferPtr, going to TokEnd that forms the token. This method 239 /// takes that range and assigns it to the token as its location and size. In 240 /// addition, since tokens cannot overlap, this also updates BufferPtr to be 241 /// TokEnd. 242 void FormTokenWithChars(Token &Result, const char *TokEnd, 243 tok::TokenKind Kind) { 244 unsigned TokLen = TokEnd-BufferPtr; 245 Result.setLength(TokLen); 246 Result.setLocation(getSourceLocation(BufferPtr, TokLen)); 247 Result.setKind(Kind); 248 BufferPtr = TokEnd; 249 } 250 251 /// isNextPPTokenLParen - Return 1 if the next unexpanded token will return a 252 /// tok::l_paren token, 0 if it is something else and 2 if there are no more 253 /// tokens in the buffer controlled by this lexer. 254 unsigned isNextPPTokenLParen(); 255 256 //===--------------------------------------------------------------------===// 257 // Lexer character reading interfaces. 258public: 259 260 // This lexer is built on two interfaces for reading characters, both of which 261 // automatically provide phase 1/2 translation. getAndAdvanceChar is used 262 // when we know that we will be reading a character from the input buffer and 263 // that this character will be part of the result token. This occurs in (f.e.) 264 // string processing, because we know we need to read until we find the 265 // closing '"' character. 266 // 267 // The second interface is the combination of PeekCharAndSize with 268 // ConsumeChar. PeekCharAndSize reads a phase 1/2 translated character, 269 // returning it and its size. If the lexer decides that this character is 270 // part of the current token, it calls ConsumeChar on it. This two stage 271 // approach allows us to emit diagnostics for characters (e.g. warnings about 272 // trigraphs), knowing that they only are emitted if the character is 273 // consumed. 274 275 /// isObviouslySimpleCharacter - Return true if the specified character is 276 /// obviously the same in translation phase 1 and translation phase 3. This 277 /// can return false for characters that end up being the same, but it will 278 /// never return true for something that needs to be mapped. 279 static bool isObviouslySimpleCharacter(char C) { 280 return C != '?' && C != '\\'; 281 } 282 283 /// getAndAdvanceChar - Read a single 'character' from the specified buffer, 284 /// advance over it, and return it. This is tricky in several cases. Here we 285 /// just handle the trivial case and fall-back to the non-inlined 286 /// getCharAndSizeSlow method to handle the hard case. 287 inline char getAndAdvanceChar(const char *&Ptr, Token &Tok) { 288 // If this is not a trigraph and not a UCN or escaped newline, return 289 // quickly. 290 if (isObviouslySimpleCharacter(Ptr[0])) return *Ptr++; 291 292 unsigned Size = 0; 293 char C = getCharAndSizeSlow(Ptr, Size, &Tok); 294 Ptr += Size; 295 return C; 296 } 297 298private: 299 /// ConsumeChar - When a character (identified by PeekCharAndSize) is consumed 300 /// and added to a given token, check to see if there are diagnostics that 301 /// need to be emitted or flags that need to be set on the token. If so, do 302 /// it. 303 const char *ConsumeChar(const char *Ptr, unsigned Size, Token &Tok) { 304 // Normal case, we consumed exactly one token. Just return it. 305 if (Size == 1) 306 return Ptr+Size; 307 308 // Otherwise, re-lex the character with a current token, allowing 309 // diagnostics to be emitted and flags to be set. 310 Size = 0; 311 getCharAndSizeSlow(Ptr, Size, &Tok); 312 return Ptr+Size; 313 } 314 315 /// getCharAndSize - Peek a single 'character' from the specified buffer, 316 /// get its size, and return it. This is tricky in several cases. Here we 317 /// just handle the trivial case and fall-back to the non-inlined 318 /// getCharAndSizeSlow method to handle the hard case. 319 inline char getCharAndSize(const char *Ptr, unsigned &Size) { 320 // If this is not a trigraph and not a UCN or escaped newline, return 321 // quickly. 322 if (isObviouslySimpleCharacter(Ptr[0])) { 323 Size = 1; 324 return *Ptr; 325 } 326 327 Size = 0; 328 return getCharAndSizeSlow(Ptr, Size); 329 } 330 331 /// getCharAndSizeSlow - Handle the slow/uncommon case of the getCharAndSize 332 /// method. 333 char getCharAndSizeSlow(const char *Ptr, unsigned &Size, Token *Tok = 0); 334public: 335 336 /// getCharAndSizeNoWarn - Like the getCharAndSize method, but does not ever 337 /// emit a warning. 338 static inline char getCharAndSizeNoWarn(const char *Ptr, unsigned &Size, 339 const LangOptions &Features) { 340 // If this is not a trigraph and not a UCN or escaped newline, return 341 // quickly. 342 if (isObviouslySimpleCharacter(Ptr[0])) { 343 Size = 1; 344 return *Ptr; 345 } 346 347 Size = 0; 348 return getCharAndSizeSlowNoWarn(Ptr, Size, Features); 349 } 350 351 /// getEscapedNewLineSize - Return the size of the specified escaped newline, 352 /// or 0 if it is not an escaped newline. P[-1] is known to be a "\" on entry 353 /// to this function. 354 static unsigned getEscapedNewLineSize(const char *P); 355 356 /// SkipEscapedNewLines - If P points to an escaped newline (or a series of 357 /// them), skip over them and return the first non-escaped-newline found, 358 /// otherwise return P. 359 static const char *SkipEscapedNewLines(const char *P); 360private: 361 362 /// getCharAndSizeSlowNoWarn - Same as getCharAndSizeSlow, but never emits a 363 /// diagnostic. 364 static char getCharAndSizeSlowNoWarn(const char *Ptr, unsigned &Size, 365 const LangOptions &Features); 366 367 //===--------------------------------------------------------------------===// 368 // Other lexer functions. 369 370 // Helper functions to lex the remainder of a token of the specific type. 371 void LexIdentifier (Token &Result, const char *CurPtr); 372 void LexNumericConstant (Token &Result, const char *CurPtr); 373 void LexStringLiteral (Token &Result, const char *CurPtr,bool Wide); 374 void LexAngledStringLiteral(Token &Result, const char *CurPtr); 375 void LexCharConstant (Token &Result, const char *CurPtr); 376 bool LexEndOfFile (Token &Result, const char *CurPtr); 377 378 bool SkipWhitespace (Token &Result, const char *CurPtr); 379 bool SkipBCPLComment (Token &Result, const char *CurPtr); 380 bool SkipBlockComment (Token &Result, const char *CurPtr); 381 bool SaveBCPLComment (Token &Result, const char *CurPtr); 382}; 383 384 385} // end namespace clang 386 387#endif 388