1 //===--- Lexer.h - C Language Family Lexer ----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the Lexer interface.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_LEXER_H
15 #define LLVM_CLANG_LEXER_H
17 #include "clang/Lex/PreprocessorLexer.h"
18 #include "clang/Basic/LangOptions.h"
19 #include "llvm/ADT/SmallVector.h"
24 class DiagnosticsEngine;
27 class DiagnosticBuilder;
29 /// ConflictMarkerKind - Kinds of conflict marker which the lexer might be
31 enum ConflictMarkerKind {
32 /// Not within a conflict marker.
34 /// A normal or diff3 conflict marker, initiated by at least 7 <s,
35 /// separated by at least 7 =s or |s, and terminated by at least 7 >s.
37 /// A Perforce-style conflict marker, initiated by 4 >s, separated by 4 =s,
38 /// and terminated by 4 <s.
42 /// Lexer - This provides a simple interface that turns a text buffer into a
43 /// stream of tokens. This provides no support for file reading or buffering,
44 /// or buffering/seeking of tokens, only forward lexing is supported. It relies
45 /// on the specified Preprocessor object to handle preprocessor directives, etc.
46 class Lexer : public PreprocessorLexer {
47 //===--------------------------------------------------------------------===//
48 // Constant configuration values for this lexer.
49 const char *BufferStart; // Start of the buffer.
50 const char *BufferEnd; // End of the buffer.
51 SourceLocation FileLoc; // Location for start of file.
52 LangOptions Features; // Features enabled by this language (cache).
53 bool Is_PragmaLexer; // True if lexer for _Pragma handling.
55 //===--------------------------------------------------------------------===//
56 // Context-specific lexing flags set by the preprocessor.
59 /// ExtendedTokenMode - The lexer can optionally keep comments and whitespace
60 /// and return them as tokens. This is used for -C and -CC modes, and
61 /// whitespace preservation can be useful for some clients that want to lex
62 /// the file in raw mode and get every character from the file.
64 /// When this is set to 2 it returns comments and whitespace. When set to 1
65 /// it returns comments, when it is set to 0 it returns normal tokens only.
66 unsigned char ExtendedTokenMode;
68 //===--------------------------------------------------------------------===//
69 // Context that changes as the file is lexed.
70 // NOTE: any state that mutates when in raw mode must have save/restore code
71 // in Lexer::isNextPPTokenLParen.
73 // BufferPtr - Current pointer into the buffer. This is the next character
75 const char *BufferPtr;
77 // IsAtStartOfLine - True if the next lexed token should get the "start of
78 // line" flag set on it.
81 // CurrentConflictMarkerState - The kind of conflict marker we are handling.
82 ConflictMarkerKind CurrentConflictMarkerState;
84 Lexer(const Lexer&); // DO NOT IMPLEMENT
85 void operator=(const Lexer&); // DO NOT IMPLEMENT
86 friend class Preprocessor;
88 void InitLexer(const char *BufStart, const char *BufPtr, const char *BufEnd);
91 /// Lexer constructor - Create a new lexer object for the specified buffer
92 /// with the specified preprocessor managing the lexing process. This lexer
93 /// assumes that the associated file buffer and Preprocessor objects will
94 /// outlive it, so it doesn't take ownership of either of them.
95 Lexer(FileID FID, const llvm::MemoryBuffer *InputBuffer, Preprocessor &PP);
97 /// Lexer constructor - Create a new raw lexer object. This object is only
98 /// suitable for calls to 'LexRawToken'. This lexer assumes that the text
99 /// range will outlive it, so it doesn't take ownership of it.
100 Lexer(SourceLocation FileLoc, const LangOptions &Features,
101 const char *BufStart, const char *BufPtr, const char *BufEnd);
103 /// Lexer constructor - Create a new raw lexer object. This object is only
104 /// suitable for calls to 'LexRawToken'. This lexer assumes that the text
105 /// range will outlive it, so it doesn't take ownership of it.
106 Lexer(FileID FID, const llvm::MemoryBuffer *InputBuffer,
107 const SourceManager &SM, const LangOptions &Features);
109 /// Create_PragmaLexer: Lexer constructor - Create a new lexer object for
110 /// _Pragma expansion. This has a variety of magic semantics that this method
111 /// sets up. It returns a new'd Lexer that must be delete'd when done.
112 static Lexer *Create_PragmaLexer(SourceLocation SpellingLoc,
113 SourceLocation ExpansionLocStart,
114 SourceLocation ExpansionLocEnd,
115 unsigned TokLen, Preprocessor &PP);
118 /// getFeatures - Return the language features currently enabled. NOTE: this
119 /// lexer modifies features as a file is parsed!
120 const LangOptions &getFeatures() const { return Features; }
122 /// getFileLoc - Return the File Location for the file we are lexing out of.
123 /// The physical location encodes the location where the characters come from,
124 /// the virtual location encodes where we should *claim* the characters came
125 /// from. Currently this is only used by _Pragma handling.
126 SourceLocation getFileLoc() const { return FileLoc; }
128 /// Lex - Return the next token in the file. If this is the end of file, it
129 /// return the tok::eof token. Return true if an error occurred and
130 /// compilation should terminate, false if normal. This implicitly involves
131 /// the preprocessor.
132 void Lex(Token &Result) {
133 // Start a new token.
136 // NOTE, any changes here should also change code after calls to
137 // Preprocessor::HandleDirective
138 if (IsAtStartOfLine) {
139 Result.setFlag(Token::StartOfLine);
140 IsAtStartOfLine = false;
143 // Get a token. Note that this may delete the current lexer if the end of
145 LexTokenInternal(Result);
148 /// isPragmaLexer - Returns true if this Lexer is being used to lex a pragma.
149 bool isPragmaLexer() const { return Is_PragmaLexer; }
151 /// IndirectLex - An indirect call to 'Lex' that can be invoked via
152 /// the PreprocessorLexer interface.
153 void IndirectLex(Token &Result) { Lex(Result); }
155 /// LexFromRawLexer - Lex a token from a designated raw lexer (one with no
156 /// associated preprocessor object. Return true if the 'next character to
157 /// read' pointer points at the end of the lexer buffer, false otherwise.
158 bool LexFromRawLexer(Token &Result) {
159 assert(LexingRawMode && "Not already in raw mode!");
161 // Note that lexing to the end of the buffer doesn't implicitly delete the
162 // lexer when in raw mode.
163 return BufferPtr == BufferEnd;
166 /// isKeepWhitespaceMode - Return true if the lexer should return tokens for
167 /// every character in the file, including whitespace and comments. This
168 /// should only be used in raw mode, as the preprocessor is not prepared to
169 /// deal with the excess tokens.
170 bool isKeepWhitespaceMode() const {
171 return ExtendedTokenMode > 1;
174 /// SetKeepWhitespaceMode - This method lets clients enable or disable
175 /// whitespace retention mode.
176 void SetKeepWhitespaceMode(bool Val) {
177 assert((!Val || LexingRawMode) &&
178 "Can only enable whitespace retention in raw mode");
179 ExtendedTokenMode = Val ? 2 : 0;
182 /// inKeepCommentMode - Return true if the lexer should return comments as
184 bool inKeepCommentMode() const {
185 return ExtendedTokenMode > 0;
188 /// SetCommentRetentionMode - Change the comment retention mode of the lexer
189 /// to the specified mode. This is really only useful when lexing in raw
190 /// mode, because otherwise the lexer needs to manage this.
191 void SetCommentRetentionState(bool Mode) {
192 assert(!isKeepWhitespaceMode() &&
193 "Can't play with comment retention state when retaining whitespace");
194 ExtendedTokenMode = Mode ? 1 : 0;
197 const char *getBufferStart() const { return BufferStart; }
199 /// ReadToEndOfLine - Read the rest of the current preprocessor line as an
200 /// uninterpreted string. This switches the lexer out of directive mode.
201 std::string ReadToEndOfLine();
204 /// Diag - Forwarding function for diagnostics. This translate a source
205 /// position in the current buffer into a SourceLocation object for rendering.
206 DiagnosticBuilder Diag(const char *Loc, unsigned DiagID) const;
208 /// getSourceLocation - Return a source location identifier for the specified
209 /// offset in the current file.
210 SourceLocation getSourceLocation(const char *Loc, unsigned TokLen = 1) const;
212 /// getSourceLocation - Return a source location for the next character in
213 /// the current file.
214 SourceLocation getSourceLocation() { return getSourceLocation(BufferPtr); }
216 /// \brief Return the current location in the buffer.
217 const char *getBufferLocation() const { return BufferPtr; }
219 /// Stringify - Convert the specified string into a C string by escaping '\'
220 /// and " characters. This does not add surrounding ""'s to the string.
221 /// If Charify is true, this escapes the ' character instead of ".
222 static std::string Stringify(const std::string &Str, bool Charify = false);
224 /// Stringify - Convert the specified string into a C string by escaping '\'
225 /// and " characters. This does not add surrounding ""'s to the string.
226 static void Stringify(SmallVectorImpl<char> &Str);
229 /// getSpelling - This method is used to get the spelling of a token into a
230 /// preallocated buffer, instead of as an std::string. The caller is required
231 /// to allocate enough space for the token, which is guaranteed to be at least
232 /// Tok.getLength() bytes long. The length of the actual result is returned.
234 /// Note that this method may do two possible things: it may either fill in
235 /// the buffer specified with characters, or it may *change the input pointer*
236 /// to point to a constant buffer with the data already in it (avoiding a
237 /// copy). The caller is not allowed to modify the returned buffer pointer
238 /// if an internal buffer is returned.
239 static unsigned getSpelling(const Token &Tok, const char *&Buffer,
240 const SourceManager &SourceMgr,
241 const LangOptions &Features,
244 /// getSpelling() - Return the 'spelling' of the Tok token. The spelling of a
245 /// token is the characters used to represent the token in the source file
246 /// after trigraph expansion and escaped-newline folding. In particular, this
247 /// wants to get the true, uncanonicalized, spelling of things like digraphs
249 static std::string getSpelling(const Token &Tok,
250 const SourceManager &SourceMgr,
251 const LangOptions &Features,
254 /// getSpelling - This method is used to get the spelling of the
255 /// token at the given source location. If, as is usually true, it
256 /// is not necessary to copy any data, then the returned string may
257 /// not point into the provided buffer.
259 /// This method lexes at the expansion depth of the given
260 /// location and does not jump to the expansion or spelling
262 static StringRef getSpelling(SourceLocation loc,
263 SmallVectorImpl<char> &buffer,
264 const SourceManager &SourceMgr,
265 const LangOptions &Features,
268 /// MeasureTokenLength - Relex the token at the specified location and return
269 /// its length in bytes in the input file. If the token needs cleaning (e.g.
270 /// includes a trigraph or an escaped newline) then this count includes bytes
271 /// that are part of that.
272 static unsigned MeasureTokenLength(SourceLocation Loc,
273 const SourceManager &SM,
274 const LangOptions &LangOpts);
276 /// \brief Given a location any where in a source buffer, find the location
277 /// that corresponds to the beginning of the token in which the original
278 /// source location lands.
281 static SourceLocation GetBeginningOfToken(SourceLocation Loc,
282 const SourceManager &SM,
283 const LangOptions &LangOpts);
285 /// AdvanceToTokenCharacter - If the current SourceLocation specifies a
286 /// location at the start of a token, return a new location that specifies a
287 /// character within the token. This handles trigraphs and escaped newlines.
288 static SourceLocation AdvanceToTokenCharacter(SourceLocation TokStart,
290 const SourceManager &SM,
291 const LangOptions &Features);
293 /// \brief Computes the source location just past the end of the
294 /// token at this source location.
296 /// This routine can be used to produce a source location that
297 /// points just past the end of the token referenced by \p Loc, and
298 /// is generally used when a diagnostic needs to point just after a
299 /// token where it expected something different that it received. If
300 /// the returned source location would not be meaningful (e.g., if
301 /// it points into a macro), this routine returns an invalid
304 /// \param Offset an offset from the end of the token, where the source
305 /// location should refer to. The default offset (0) produces a source
306 /// location pointing just past the end of the token; an offset of 1 produces
307 /// a source location pointing to the last character in the token, etc.
308 static SourceLocation getLocForEndOfToken(SourceLocation Loc, unsigned Offset,
309 const SourceManager &SM,
310 const LangOptions &Features);
312 /// \brief Returns true if the given MacroID location points at the first
313 /// token of the macro expansion.
314 static bool isAtStartOfMacroExpansion(SourceLocation loc,
315 const SourceManager &SM,
316 const LangOptions &LangOpts);
318 /// \brief Returns true if the given MacroID location points at the last
319 /// token of the macro expansion.
320 static bool isAtEndOfMacroExpansion(SourceLocation loc,
321 const SourceManager &SM,
322 const LangOptions &LangOpts);
324 /// \brief Compute the preamble of the given file.
326 /// The preamble of a file contains the initial comments, include directives,
327 /// and other preprocessor directives that occur before the code in this
328 /// particular file actually begins. The preamble of the main source file is
329 /// a potential prefix header.
331 /// \param Buffer The memory buffer containing the file's contents.
333 /// \param MaxLines If non-zero, restrict the length of the preamble
334 /// to fewer than this number of lines.
336 /// \returns The offset into the file where the preamble ends and the rest
337 /// of the file begins along with a boolean value indicating whether
338 /// the preamble ends at the beginning of a new line.
339 static std::pair<unsigned, bool>
340 ComputePreamble(const llvm::MemoryBuffer *Buffer, const LangOptions &Features,
341 unsigned MaxLines = 0);
343 //===--------------------------------------------------------------------===//
344 // Internal implementation interfaces.
347 /// LexTokenInternal - Internal interface to lex a preprocessing token. Called
350 void LexTokenInternal(Token &Result);
352 /// FormTokenWithChars - When we lex a token, we have identified a span
353 /// starting at BufferPtr, going to TokEnd that forms the token. This method
354 /// takes that range and assigns it to the token as its location and size. In
355 /// addition, since tokens cannot overlap, this also updates BufferPtr to be
357 void FormTokenWithChars(Token &Result, const char *TokEnd,
358 tok::TokenKind Kind) {
359 unsigned TokLen = TokEnd-BufferPtr;
360 Result.setLength(TokLen);
361 Result.setLocation(getSourceLocation(BufferPtr, TokLen));
362 Result.setKind(Kind);
366 /// isNextPPTokenLParen - Return 1 if the next unexpanded token will return a
367 /// tok::l_paren token, 0 if it is something else and 2 if there are no more
368 /// tokens in the buffer controlled by this lexer.
369 unsigned isNextPPTokenLParen();
371 //===--------------------------------------------------------------------===//
372 // Lexer character reading interfaces.
375 // This lexer is built on two interfaces for reading characters, both of which
376 // automatically provide phase 1/2 translation. getAndAdvanceChar is used
377 // when we know that we will be reading a character from the input buffer and
378 // that this character will be part of the result token. This occurs in (f.e.)
379 // string processing, because we know we need to read until we find the
380 // closing '"' character.
382 // The second interface is the combination of getCharAndSize with
383 // ConsumeChar. getCharAndSize reads a phase 1/2 translated character,
384 // returning it and its size. If the lexer decides that this character is
385 // part of the current token, it calls ConsumeChar on it. This two stage
386 // approach allows us to emit diagnostics for characters (e.g. warnings about
387 // trigraphs), knowing that they only are emitted if the character is
390 /// isObviouslySimpleCharacter - Return true if the specified character is
391 /// obviously the same in translation phase 1 and translation phase 3. This
392 /// can return false for characters that end up being the same, but it will
393 /// never return true for something that needs to be mapped.
394 static bool isObviouslySimpleCharacter(char C) {
395 return C != '?' && C != '\\';
398 /// getAndAdvanceChar - Read a single 'character' from the specified buffer,
399 /// advance over it, and return it. This is tricky in several cases. Here we
400 /// just handle the trivial case and fall-back to the non-inlined
401 /// getCharAndSizeSlow method to handle the hard case.
402 inline char getAndAdvanceChar(const char *&Ptr, Token &Tok) {
403 // If this is not a trigraph and not a UCN or escaped newline, return
405 if (isObviouslySimpleCharacter(Ptr[0])) return *Ptr++;
408 char C = getCharAndSizeSlow(Ptr, Size, &Tok);
414 /// ConsumeChar - When a character (identified by getCharAndSize) is consumed
415 /// and added to a given token, check to see if there are diagnostics that
416 /// need to be emitted or flags that need to be set on the token. If so, do
418 const char *ConsumeChar(const char *Ptr, unsigned Size, Token &Tok) {
419 // Normal case, we consumed exactly one token. Just return it.
423 // Otherwise, re-lex the character with a current token, allowing
424 // diagnostics to be emitted and flags to be set.
426 getCharAndSizeSlow(Ptr, Size, &Tok);
430 /// getCharAndSize - Peek a single 'character' from the specified buffer,
431 /// get its size, and return it. This is tricky in several cases. Here we
432 /// just handle the trivial case and fall-back to the non-inlined
433 /// getCharAndSizeSlow method to handle the hard case.
434 inline char getCharAndSize(const char *Ptr, unsigned &Size) {
435 // If this is not a trigraph and not a UCN or escaped newline, return
437 if (isObviouslySimpleCharacter(Ptr[0])) {
443 return getCharAndSizeSlow(Ptr, Size);
446 /// getCharAndSizeSlow - Handle the slow/uncommon case of the getCharAndSize
448 char getCharAndSizeSlow(const char *Ptr, unsigned &Size, Token *Tok = 0);
451 /// getCharAndSizeNoWarn - Like the getCharAndSize method, but does not ever
453 static inline char getCharAndSizeNoWarn(const char *Ptr, unsigned &Size,
454 const LangOptions &Features) {
455 // If this is not a trigraph and not a UCN or escaped newline, return
457 if (isObviouslySimpleCharacter(Ptr[0])) {
463 return getCharAndSizeSlowNoWarn(Ptr, Size, Features);
466 /// getEscapedNewLineSize - Return the size of the specified escaped newline,
467 /// or 0 if it is not an escaped newline. P[-1] is known to be a "\" on entry
468 /// to this function.
469 static unsigned getEscapedNewLineSize(const char *P);
471 /// SkipEscapedNewLines - If P points to an escaped newline (or a series of
472 /// them), skip over them and return the first non-escaped-newline found,
473 /// otherwise return P.
474 static const char *SkipEscapedNewLines(const char *P);
476 /// \brief Checks that the given token is the first token that occurs after
477 /// the given location (this excludes comments and whitespace). Returns the
478 /// location immediately after the specified token. If the token is not found
479 /// or the location is inside a macro, the returned source location will be
481 static SourceLocation findLocationAfterToken(SourceLocation loc,
482 tok::TokenKind TKind,
483 const SourceManager &SM,
484 const LangOptions &LangOpts,
485 bool SkipTrailingWhitespaceAndNewLine);
489 /// getCharAndSizeSlowNoWarn - Same as getCharAndSizeSlow, but never emits a
491 static char getCharAndSizeSlowNoWarn(const char *Ptr, unsigned &Size,
492 const LangOptions &Features);
494 //===--------------------------------------------------------------------===//
495 // Other lexer functions.
497 void SkipBytes(unsigned Bytes, bool StartOfLine);
499 // Helper functions to lex the remainder of a token of the specific type.
500 void LexIdentifier (Token &Result, const char *CurPtr);
501 void LexNumericConstant (Token &Result, const char *CurPtr);
502 void LexStringLiteral (Token &Result, const char *CurPtr,
503 tok::TokenKind Kind);
504 void LexRawStringLiteral (Token &Result, const char *CurPtr,
505 tok::TokenKind Kind);
506 void LexAngledStringLiteral(Token &Result, const char *CurPtr);
507 void LexCharConstant (Token &Result, const char *CurPtr,
508 tok::TokenKind Kind);
509 bool LexEndOfFile (Token &Result, const char *CurPtr);
511 bool SkipWhitespace (Token &Result, const char *CurPtr);
512 bool SkipBCPLComment (Token &Result, const char *CurPtr);
513 bool SkipBlockComment (Token &Result, const char *CurPtr);
514 bool SaveBCPLComment (Token &Result, const char *CurPtr);
516 bool IsStartOfConflictMarker(const char *CurPtr);
517 bool HandleEndOfConflictMarker(const char *CurPtr);
519 bool isCodeCompletionPoint(const char *CurPtr) const;
520 void cutOffLexing() { BufferPtr = BufferEnd; }
524 } // end namespace clang