TokenConcatenation.h revision d7038e18ef540a78fe6ce2a43125ce9b08fdbbc5 
1//===--- TokenConcatenation.h - Token Concatenation Avoidance ---*- 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 TokenConcatenation class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef CLANG_LEX_TOKEN_CONCATENATION_H
15#define CLANG_LEX_TOKEN_CONCATENATION_H
16
17#include "clang/Basic/TokenKinds.h"
18
19namespace clang {
20  class Preprocessor;
21  class Token;
22
23  /// TokenConcatenation class, which answers the question of
24  ///   "Is it safe to emit two tokens without a whitespace between them, or
25  ///    would that cause implicit concatenation of the tokens?"
26  ///
27  /// For example, it emitting two identifiers "foo" and "bar" next to each
28  /// other would cause the lexer to produce one "foobar" token.  Emitting "1"
29  /// and ")" next to each other is safe.
30  ///
31  class TokenConcatenation {
32    Preprocessor &PP;
33
34    enum AvoidConcatInfo {
35      /// By default, a token never needs to avoid concatenation.  Most tokens
36      /// (e.g. ',', ')', etc) don't cause a problem when concatenated.
37      aci_never_avoid_concat = 0,
38
39      /// aci_custom_firstchar - AvoidConcat contains custom code to handle this
40      /// token's requirements, and it needs to know the first character of the
41      /// token.
42      aci_custom_firstchar = 1,
43
44      /// aci_custom - AvoidConcat contains custom code to handle this token's
45      /// requirements, but it doesn't need to know the first character of the
46      /// token.
47      aci_custom = 2,
48
49      /// aci_avoid_equal - Many tokens cannot be safely followed by an '='
50      /// character.  For example, "<<" turns into "<<=" when followed by an =.
51      aci_avoid_equal = 4
52    };
53
54    /// TokenInfo - This array contains information for each token on what
55    /// action to take when avoiding concatenation of tokens in the AvoidConcat
56    /// method.
57    char TokenInfo[tok::NUM_TOKENS];
58  public:
59    TokenConcatenation(Preprocessor &PP);
60
61    bool AvoidConcat(const Token &PrevTok, const Token &Tok) const;
62
63  private:
64    /// StartsWithL - Return true if the spelling of this token starts with 'L'.
65    bool StartsWithL(const Token &Tok) const;
66
67    /// IsIdentifierL - Return true if the spelling of this token is literally
68    /// 'L'.
69    bool IsIdentifierL(const Token &Tok) const;
70  };
71  } // end clang namespace
72
73#endif
74