TokenLexer.h revision 21ec0e4c5db85e45b59cafabca66d640e0ee2dcc 
1//===--- TokenLexer.h - Lex from a token buffer -----------------*- 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 TokenLexer interface.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_TOKENLEXER_H
15#define LLVM_CLANG_TOKENLEXER_H
16
17#include "clang/Basic/SourceLocation.h"
18
19namespace clang {
20  class MacroInfo;
21  class Preprocessor;
22  class Token;
23  class MacroArgs;
24
25/// TokenLexer - This implements a lexer that returns token from a macro body
26/// or token stream instead of lexing from a character buffer.  This is used for
27/// macro expansion and _Pragma handling, for example.
28///
29class TokenLexer {
30  /// Macro - The macro we are expanding from.  This is null if expanding a
31  /// token stream.
32  ///
33  MacroInfo *Macro;
34
35  /// ActualArgs - The actual arguments specified for a function-like macro, or
36  /// null.  The TokenLexer owns the pointed-to object.
37  MacroArgs *ActualArgs;
38
39  /// PP - The current preprocessor object we are expanding for.
40  ///
41  Preprocessor &PP;
42
43  /// Tokens - This is the pointer to an array of tokens that the macro is
44  /// defined to, with arguments expanded for function-like macros.  If this is
45  /// a token stream, these are the tokens we are returning.
46  const Token *Tokens;
47
48  /// NumTokens - This is the length of the Tokens array.
49  ///
50  unsigned NumTokens;
51
52  /// CurToken - This is the next token that Lex will return.
53  ///
54  unsigned CurToken;
55
56  /// InstantiateLoc - The source location where this macro was instantiated.
57  ///
58  SourceLocation InstantiateLoc;
59
60  /// Lexical information about the expansion point of the macro: the identifier
61  /// that the macro expanded from had these properties.
62  bool AtStartOfLine : 1;
63  bool HasLeadingSpace : 1;
64
65  /// OwnsTokens - This is true if this TokenLexer allocated the Tokens
66  /// array, and thus needs to free it when destroyed.  For simple object-like
67  /// macros (for example) we just point into the token buffer of the macro
68  /// definition, we don't make a copy of it.
69  bool OwnsTokens : 1;
70
71  /// DisableMacroExpansion - This is true when tokens lexed from the TokenLexer
72  /// should not be subject to further macro expansion.
73  bool DisableMacroExpansion : 1;
74
75  TokenLexer(const TokenLexer&);  // DO NOT IMPLEMENT
76  void operator=(const TokenLexer&); // DO NOT IMPLEMENT
77public:
78  /// Create a TokenLexer for the specified macro with the specified actual
79  /// arguments.  Note that this ctor takes ownership of the ActualArgs pointer.
80  TokenLexer(Token &Tok, MacroArgs *ActualArgs, Preprocessor &pp)
81    : Macro(0), ActualArgs(0), PP(pp), OwnsTokens(false) {
82    Init(Tok, ActualArgs);
83  }
84
85  /// Init - Initialize this TokenLexer to expand from the specified macro
86  /// with the specified argument information.  Note that this ctor takes
87  /// ownership of the ActualArgs pointer.
88  void Init(Token &Tok, MacroArgs *ActualArgs);
89
90  /// Create a TokenLexer for the specified token stream.  If 'OwnsTokens' is
91  /// specified, this takes ownership of the tokens and delete[]'s them when
92  /// the token lexer is empty.
93  TokenLexer(const Token *TokArray, unsigned NumToks, bool DisableExpansion,
94             bool ownsTokens, Preprocessor &pp)
95    : Macro(0), ActualArgs(0), PP(pp), OwnsTokens(false) {
96    Init(TokArray, NumToks, DisableExpansion, ownsTokens);
97  }
98
99  /// Init - Initialize this TokenLexer with the specified token stream.
100  /// This does not take ownership of the specified token vector.
101  ///
102  /// DisableExpansion is true when macro expansion of tokens lexed from this
103  /// stream should be disabled.
104  void Init(const Token *TokArray, unsigned NumToks,
105            bool DisableMacroExpansion, bool OwnsTokens);
106
107  ~TokenLexer() { destroy(); }
108
109  /// isNextTokenLParen - If the next token lexed will pop this macro off the
110  /// expansion stack, return 2.  If the next unexpanded token is a '(', return
111  /// 1, otherwise return 0.
112  unsigned isNextTokenLParen() const;
113
114  /// Lex - Lex and return a token from this macro stream.
115  void Lex(Token &Tok);
116
117private:
118  void destroy();
119
120  /// isAtEnd - Return true if the next lex call will pop this macro off the
121  /// include stack.
122  bool isAtEnd() const {
123    return CurToken == NumTokens;
124  }
125
126  /// PasteTokens - Tok is the LHS of a ## operator, and CurToken is the ##
127  /// operator.  Read the ## and RHS, and paste the LHS/RHS together.  If there
128  /// are is another ## after it, chomp it iteratively.  Return the result as
129  /// Tok.  If this returns true, the caller should immediately return the
130  /// token.
131  bool PasteTokens(Token &Tok);
132
133  /// Expand the arguments of a function-like macro so that we can quickly
134  /// return preexpanded tokens from Tokens.
135  void ExpandFunctionArguments();
136
137  /// HandleMicrosoftCommentPaste - In microsoft compatibility mode, /##/ pastes
138  /// together to form a comment that comments out everything in the current
139  /// macro, other active macros, and anything left on the current physical
140  /// source line of the instantiated buffer.  Handle this by returning the
141  /// first token on the next line.
142  void HandleMicrosoftCommentPaste(Token &Tok);
143};
144
145}  // end namespace clang
146
147#endif
148