1 //===- clang/Lex/DependencyDirectivesSourceMinimizer.h -  ----------*- 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 /// This is the interface for minimizing header and source files to the
11 /// minimum necessary preprocessor directives for evaluating includes. It
12 /// reduces the source down to #define, #include, #import, @import, and any
13 /// conditional preprocessor logic that contains one of those.
14 ///
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H
18 #define LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H
19 
20 #include "clang/Basic/SourceLocation.h"
21 #include "llvm/ADT/ArrayRef.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/StringRef.h"
24 
25 namespace clang {
26 
27 class DiagnosticsEngine;
28 
29 namespace minimize_source_to_dependency_directives {
30 
31 /// Represents the kind of preprocessor directive or a module declaration that
32 /// is tracked by the source minimizer in its token output.
33 enum TokenKind {
34   pp_none,
35   pp_include,
36   pp___include_macros,
37   pp_define,
38   pp_undef,
39   pp_import,
40   pp_pragma_import,
41   pp_pragma_once,
42   pp_include_next,
43   pp_if,
44   pp_ifdef,
45   pp_ifndef,
46   pp_elif,
47   pp_elifdef,
48   pp_elifndef,
49   pp_else,
50   pp_endif,
51   decl_at_import,
52   cxx_export_decl,
53   cxx_module_decl,
54   cxx_import_decl,
55   pp_eof,
56 };
57 
58 /// Represents a simplified token that's lexed as part of the source
59 /// minimization. It's used to track the location of various preprocessor
60 /// directives that could potentially have an effect on the depedencies.
61 struct Token {
62   /// The kind of token.
63   TokenKind K = pp_none;
64 
65   /// Offset into the output byte stream of where the directive begins.
66   int Offset = -1;
67 
TokenToken68   Token(TokenKind K, int Offset) : K(K), Offset(Offset) {}
69 };
70 
71 /// Simplified token range to track the range of a potentially skippable PP
72 /// directive.
73 struct SkippedRange {
74   /// Offset into the output byte stream of where the skipped directive begins.
75   int Offset;
76 
77   /// The number of bytes that can be skipped before the preprocessing must
78   /// resume.
79   int Length;
80 };
81 
82 /// Computes the potential source ranges that can be skipped by the preprocessor
83 /// when skipping a directive like #if, #ifdef or #elsif.
84 ///
85 /// \returns false on success, true on error.
86 bool computeSkippedRanges(ArrayRef<Token> Input,
87                           llvm::SmallVectorImpl<SkippedRange> &Range);
88 
89 } // end namespace minimize_source_to_dependency_directives
90 
91 /// Minimize the input down to the preprocessor directives that might have
92 /// an effect on the dependencies for a compilation unit.
93 ///
94 /// This function deletes all non-preprocessor code, and strips anything that
95 /// can't affect what gets included. It canonicalizes whitespace where
96 /// convenient to stabilize the output against formatting changes in the input.
97 ///
98 /// Clears the output vectors at the beginning of the call.
99 ///
100 /// \returns false on success, true on error. If the diagnostic engine is not
101 /// null, an appropriate error is reported using the given input location
102 /// with the offset that corresponds to the minimizer's current buffer offset.
103 bool minimizeSourceToDependencyDirectives(
104     llvm::StringRef Input, llvm::SmallVectorImpl<char> &Output,
105     llvm::SmallVectorImpl<minimize_source_to_dependency_directives::Token>
106         &Tokens,
107     DiagnosticsEngine *Diags = nullptr,
108     SourceLocation InputSourceLoc = SourceLocation());
109 
110 } // end namespace clang
111 
112 #endif // LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H
113