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      1 //===--- PreprocessorLexer.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 PreprocessorLexer interface.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_CLANG_PreprocessorLexer_H
     15 #define LLVM_CLANG_PreprocessorLexer_H
     16 
     17 #include "clang/Lex/MultipleIncludeOpt.h"
     18 #include "clang/Lex/Token.h"
     19 #include "llvm/ADT/SmallVector.h"
     20 
     21 namespace clang {
     22 
     23 class FileEntry;
     24 class Preprocessor;
     25 
     26 class PreprocessorLexer {
     27 protected:
     28   Preprocessor *PP;              // Preprocessor object controlling lexing.
     29 
     30   /// The SourceManager FileID corresponding to the file being lexed.
     31   const FileID FID;
     32 
     33   /// \brief Number of SLocEntries before lexing the file.
     34   unsigned InitialNumSLocEntries;
     35 
     36   //===--------------------------------------------------------------------===//
     37   // Context-specific lexing flags set by the preprocessor.
     38   //===--------------------------------------------------------------------===//
     39 
     40   /// ParsingPreprocessorDirective - This is true when parsing #XXX.  This turns
     41   /// '\n' into a tok::eod token.
     42   bool ParsingPreprocessorDirective;
     43 
     44   /// ParsingFilename - True after #include: this turns <xx> into a
     45   /// tok::angle_string_literal token.
     46   bool ParsingFilename;
     47 
     48   /// LexingRawMode - True if in raw mode:  This flag disables interpretation of
     49   /// tokens and is a far faster mode to lex in than non-raw-mode.  This flag:
     50   ///  1. If EOF of the current lexer is found, the include stack isn't popped.
     51   ///  2. Identifier information is not looked up for identifier tokens.  As an
     52   ///     effect of this, implicit macro expansion is naturally disabled.
     53   ///  3. "#" tokens at the start of a line are treated as normal tokens, not
     54   ///     implicitly transformed by the lexer.
     55   ///  4. All diagnostic messages are disabled.
     56   ///  5. No callbacks are made into the preprocessor.
     57   ///
     58   /// Note that in raw mode that the PP pointer may be null.
     59   bool LexingRawMode;
     60 
     61   /// MIOpt - This is a state machine that detects the #ifndef-wrapping a file
     62   /// idiom for the multiple-include optimization.
     63   MultipleIncludeOpt MIOpt;
     64 
     65   /// ConditionalStack - Information about the set of #if/#ifdef/#ifndef blocks
     66   /// we are currently in.
     67   SmallVector<PPConditionalInfo, 4> ConditionalStack;
     68 
     69   PreprocessorLexer(const PreprocessorLexer&);          // DO NOT IMPLEMENT
     70   void operator=(const PreprocessorLexer&); // DO NOT IMPLEMENT
     71   friend class Preprocessor;
     72 
     73   PreprocessorLexer(Preprocessor *pp, FileID fid);
     74 
     75   PreprocessorLexer()
     76     : PP(0), InitialNumSLocEntries(0),
     77       ParsingPreprocessorDirective(false),
     78       ParsingFilename(false),
     79       LexingRawMode(false) {}
     80 
     81   virtual ~PreprocessorLexer() {}
     82 
     83   virtual void IndirectLex(Token& Result) = 0;
     84 
     85   /// getSourceLocation - Return the source location for the next observable
     86   ///  location.
     87   virtual SourceLocation getSourceLocation() = 0;
     88 
     89   //===--------------------------------------------------------------------===//
     90   // #if directive handling.
     91 
     92   /// pushConditionalLevel - When we enter a #if directive, this keeps track of
     93   /// what we are currently in for diagnostic emission (e.g. #if with missing
     94   /// #endif).
     95   void pushConditionalLevel(SourceLocation DirectiveStart, bool WasSkipping,
     96                             bool FoundNonSkip, bool FoundElse) {
     97     PPConditionalInfo CI;
     98     CI.IfLoc = DirectiveStart;
     99     CI.WasSkipping = WasSkipping;
    100     CI.FoundNonSkip = FoundNonSkip;
    101     CI.FoundElse = FoundElse;
    102     ConditionalStack.push_back(CI);
    103   }
    104   void pushConditionalLevel(const PPConditionalInfo &CI) {
    105     ConditionalStack.push_back(CI);
    106   }
    107 
    108   /// popConditionalLevel - Remove an entry off the top of the conditional
    109   /// stack, returning information about it.  If the conditional stack is empty,
    110   /// this returns true and does not fill in the arguments.
    111   bool popConditionalLevel(PPConditionalInfo &CI) {
    112     if (ConditionalStack.empty()) return true;
    113     CI = ConditionalStack.back();
    114     ConditionalStack.pop_back();
    115     return false;
    116   }
    117 
    118   /// peekConditionalLevel - Return the top of the conditional stack.  This
    119   /// requires that there be a conditional active.
    120   PPConditionalInfo &peekConditionalLevel() {
    121     assert(!ConditionalStack.empty() && "No conditionals active!");
    122     return ConditionalStack.back();
    123   }
    124 
    125   unsigned getConditionalStackDepth() const { return ConditionalStack.size(); }
    126 
    127 public:
    128 
    129   //===--------------------------------------------------------------------===//
    130   // Misc. lexing methods.
    131 
    132   /// LexIncludeFilename - After the preprocessor has parsed a #include, lex and
    133   /// (potentially) macro expand the filename.  If the sequence parsed is not
    134   /// lexically legal, emit a diagnostic and return a result EOD token.
    135   void LexIncludeFilename(Token &Result);
    136 
    137   /// setParsingPreprocessorDirective - Inform the lexer whether or not
    138   ///  we are currently lexing a preprocessor directive.
    139   void setParsingPreprocessorDirective(bool f) {
    140     ParsingPreprocessorDirective = f;
    141   }
    142 
    143   /// isLexingRawMode - Return true if this lexer is in raw mode or not.
    144   bool isLexingRawMode() const { return LexingRawMode; }
    145 
    146   /// getPP - Return the preprocessor object for this lexer.
    147   Preprocessor *getPP() const { return PP; }
    148 
    149   FileID getFileID() const {
    150     assert(PP &&
    151       "PreprocessorLexer::getFileID() should only be used with a Preprocessor");
    152     return FID;
    153   }
    154 
    155   /// \brief Number of SLocEntries before lexing the file.
    156   unsigned getInitialNumSLocEntries() const {
    157     return InitialNumSLocEntries;
    158   }
    159 
    160   /// getFileEntry - Return the FileEntry corresponding to this FileID.  Like
    161   /// getFileID(), this only works for lexers with attached preprocessors.
    162   const FileEntry *getFileEntry() const;
    163 
    164   /// \brief Iterator that traverses the current stack of preprocessor
    165   /// conditional directives (#if/#ifdef/#ifndef).
    166   typedef SmallVectorImpl<PPConditionalInfo>::const_iterator
    167     conditional_iterator;
    168 
    169   conditional_iterator conditional_begin() const {
    170     return ConditionalStack.begin();
    171   }
    172   conditional_iterator conditional_end() const {
    173     return ConditionalStack.end();
    174   }
    175 };
    176 
    177 }  // end namespace clang
    178 
    179 #endif
    180