1//===--- TokenConcatenation.h - Token Concatenation Avoidance ---*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the TokenConcatenation class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_LEX_TOKENCONCATENATION_H
14#define LLVM_CLANG_LEX_TOKENCONCATENATION_H
15
16#include "clang/Basic/TokenKinds.h"
17
18namespace clang {
19  class Preprocessor;
20  class Token;
21
22  /// TokenConcatenation class, which answers the question of
23  ///   "Is it safe to emit two tokens without a whitespace between them, or
24  ///    would that cause implicit concatenation of the tokens?"
25  ///
26  /// For example, it emitting two identifiers "foo" and "bar" next to each
27  /// other would cause the lexer to produce one "foobar" token.  Emitting "1"
28  /// and ")" next to each other is safe.
29  ///
30  class TokenConcatenation {
31    const Preprocessor &PP;
32
33    enum AvoidConcatInfo {
34      /// By default, a token never needs to avoid concatenation.  Most tokens
35      /// (e.g. ',', ')', etc) don't cause a problem when concatenated.
36      aci_never_avoid_concat = 0,
37
38      /// aci_custom_firstchar - AvoidConcat contains custom code to handle this
39      /// token's requirements, and it needs to know the first character of the
40      /// token.
41      aci_custom_firstchar = 1,
42
43      /// aci_custom - AvoidConcat contains custom code to handle this token's
44      /// requirements, but it doesn't need to know the first character of the
45      /// token.
46      aci_custom = 2,
47
48      /// aci_avoid_equal - Many tokens cannot be safely followed by an '='
49      /// character.  For example, "<<" turns into "<<=" when followed by an =.
50      aci_avoid_equal = 4
51    };
52
53    /// TokenInfo - This array contains information for each token on what
54    /// action to take when avoiding concatenation of tokens in the AvoidConcat
55    /// method.
56    char TokenInfo[tok::NUM_TOKENS];
57  public:
58    TokenConcatenation(const Preprocessor &PP);
59
60    bool AvoidConcat(const Token &PrevPrevTok,
61                     const Token &PrevTok,
62                     const Token &Tok) const;
63
64  private:
65    /// IsIdentifierStringPrefix - Return true if the spelling of the token
66    /// is literally 'L', 'u', 'U', or 'u8'.
67    bool IsIdentifierStringPrefix(const Token &Tok) const;
68  };
69  } // end clang namespace
70
71#endif
72