1//===- PreprocessorLexer.h - C Language Family Lexer ------------*- 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/// \file
10/// Defines the PreprocessorLexer interface.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LEX_PREPROCESSORLEXER_H
15#define LLVM_CLANG_LEX_PREPROCESSORLEXER_H
16
17#include "clang/Basic/FileEntry.h"
18#include "clang/Basic/SourceLocation.h"
19#include "clang/Lex/MultipleIncludeOpt.h"
20#include "clang/Lex/Token.h"
21#include "llvm/ADT/ArrayRef.h"
22#include "llvm/ADT/SmallVector.h"
23#include <cassert>
24
25namespace clang {
26
27class FileEntry;
28class Preprocessor;
29
30class PreprocessorLexer {
31  virtual void anchor();
32
33protected:
34  friend class Preprocessor;
35
36  // Preprocessor object controlling lexing.
37  Preprocessor *PP = nullptr;
38
39  /// The SourceManager FileID corresponding to the file being lexed.
40  const FileID FID;
41
42  /// Number of SLocEntries before lexing the file.
43  unsigned InitialNumSLocEntries = 0;
44
45  //===--------------------------------------------------------------------===//
46  // Context-specific lexing flags set by the preprocessor.
47  //===--------------------------------------------------------------------===//
48
49  /// True when parsing \#XXX; turns '\\n' into a tok::eod token.
50  bool ParsingPreprocessorDirective = false;
51
52  /// True after \#include; turns \<xx> or "xxx" into a tok::header_name token.
53  bool ParsingFilename = false;
54
55  /// True if in raw mode.
56  ///
57  /// Raw mode disables interpretation of tokens and is a far faster mode to
58  /// lex in than non-raw-mode.  This flag:
59  ///  1. If EOF of the current lexer is found, the include stack isn't popped.
60  ///  2. Identifier information is not looked up for identifier tokens.  As an
61  ///     effect of this, implicit macro expansion is naturally disabled.
62  ///  3. "#" tokens at the start of a line are treated as normal tokens, not
63  ///     implicitly transformed by the lexer.
64  ///  4. All diagnostic messages are disabled.
65  ///  5. No callbacks are made into the preprocessor.
66  ///
67  /// Note that in raw mode that the PP pointer may be null.
68  bool LexingRawMode = false;
69
70  /// A state machine that detects the \#ifndef-wrapping a file
71  /// idiom for the multiple-include optimization.
72  MultipleIncludeOpt MIOpt;
73
74  /// Information about the set of \#if/\#ifdef/\#ifndef blocks
75  /// we are currently in.
76  SmallVector<PPConditionalInfo, 4> ConditionalStack;
77
78  PreprocessorLexer() : FID() {}
79  PreprocessorLexer(Preprocessor *pp, FileID fid);
80  virtual ~PreprocessorLexer() = default;
81
82  virtual void IndirectLex(Token& Result) = 0;
83
84  /// Return the source location for the next observable location.
85  virtual SourceLocation getSourceLocation() = 0;
86
87  //===--------------------------------------------------------------------===//
88  // #if directive handling.
89
90  /// pushConditionalLevel - When we enter a \#if directive, this keeps track of
91  /// what we are currently in for diagnostic emission (e.g. \#if with missing
92  /// \#endif).
93  void pushConditionalLevel(SourceLocation DirectiveStart, bool WasSkipping,
94                            bool FoundNonSkip, bool FoundElse) {
95    PPConditionalInfo CI;
96    CI.IfLoc = DirectiveStart;
97    CI.WasSkipping = WasSkipping;
98    CI.FoundNonSkip = FoundNonSkip;
99    CI.FoundElse = FoundElse;
100    ConditionalStack.push_back(CI);
101  }
102  void pushConditionalLevel(const PPConditionalInfo &CI) {
103    ConditionalStack.push_back(CI);
104  }
105
106  /// popConditionalLevel - Remove an entry off the top of the conditional
107  /// stack, returning information about it.  If the conditional stack is empty,
108  /// this returns true and does not fill in the arguments.
109  bool popConditionalLevel(PPConditionalInfo &CI) {
110    if (ConditionalStack.empty())
111      return true;
112    CI = ConditionalStack.pop_back_val();
113    return false;
114  }
115
116  /// Return the top of the conditional stack.
117  /// \pre This requires that there be a conditional active.
118  PPConditionalInfo &peekConditionalLevel() {
119    assert(!ConditionalStack.empty() && "No conditionals active!");
120    return ConditionalStack.back();
121  }
122
123  unsigned getConditionalStackDepth() const { return ConditionalStack.size(); }
124
125public:
126  PreprocessorLexer(const PreprocessorLexer &) = delete;
127  PreprocessorLexer &operator=(const PreprocessorLexer &) = delete;
128
129  //===--------------------------------------------------------------------===//
130  // Misc. lexing methods.
131
132  /// Lex a token, producing a header-name token if possible.
133  void LexIncludeFilename(Token &FilenameTok);
134
135  /// Inform the lexer whether or not we are currently lexing a
136  /// preprocessor directive.
137  void setParsingPreprocessorDirective(bool f) {
138    ParsingPreprocessorDirective = f;
139  }
140
141  /// Return true if this lexer is in raw mode or not.
142  bool isLexingRawMode() const { return LexingRawMode; }
143
144  /// Return the preprocessor object for this lexer.
145  Preprocessor *getPP() const { return PP; }
146
147  FileID getFileID() const {
148    assert(PP &&
149      "PreprocessorLexer::getFileID() should only be used with a Preprocessor");
150    return FID;
151  }
152
153  /// Number of SLocEntries before lexing the file.
154  unsigned getInitialNumSLocEntries() const {
155    return InitialNumSLocEntries;
156  }
157
158  /// getFileEntry - Return the FileEntry corresponding to this FileID.  Like
159  /// getFileID(), this only works for lexers with attached preprocessors.
160  OptionalFileEntryRefDegradesToFileEntryPtr getFileEntry() const;
161
162  /// Iterator that traverses the current stack of preprocessor
163  /// conditional directives (\#if/\#ifdef/\#ifndef).
164  using conditional_iterator =
165      SmallVectorImpl<PPConditionalInfo>::const_iterator;
166
167  conditional_iterator conditional_begin() const {
168    return ConditionalStack.begin();
169  }
170
171  conditional_iterator conditional_end() const {
172    return ConditionalStack.end();
173  }
174
175  void setConditionalLevels(ArrayRef<PPConditionalInfo> CL) {
176    ConditionalStack.clear();
177    ConditionalStack.append(CL.begin(), CL.end());
178  }
179};
180
181} // namespace clang
182
183#endif // LLVM_CLANG_LEX_PREPROCESSORLEXER_H
184