clang  10.0.0svn
FileMatchTrie.h
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1 //===- FileMatchTrie.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 // This file implements a match trie to find the matching file in a compilation
10 // database based on a given path in the presence of symlinks.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_TOOLING_FILEMATCHTRIE_H
15 #define LLVM_CLANG_TOOLING_FILEMATCHTRIE_H
16 
17 #include "clang/Basic/LLVM.h"
18 #include "llvm/ADT/StringRef.h"
19 #include <memory>
20 
21 namespace clang {
22 namespace tooling {
23 
24 class FileMatchTrieNode;
25 
27  virtual ~PathComparator() = default;
28 
29  virtual bool equivalent(StringRef FileA, StringRef FileB) const = 0;
30 };
31 
32 /// A trie to efficiently match against the entries of the compilation
33 /// database in order of matching suffix length.
34 ///
35 /// When a clang tool is supposed to operate on a specific file, we have to
36 /// find the corresponding file in the compilation database. Although entries
37 /// in the compilation database are keyed by filename, a simple string match
38 /// is insufficient because of symlinks. Commonly, a project hierarchy looks
39 /// like this:
40 /// /<project-root>/src/<path>/<somefile>.cc (used as input for the tool)
41 /// /<project-root>/build/<symlink-to-src>/<path>/<somefile>.cc (stored in DB)
42 ///
43 /// Furthermore, there might be symlinks inside the source folder or inside the
44 /// database, so that the same source file is translated with different build
45 /// options.
46 ///
47 /// For a given input file, the \c FileMatchTrie finds its entries in order
48 /// of matching suffix length. For each suffix length, there might be one or
49 /// more entries in the database. For each of those entries, it calls
50 /// \c llvm::sys::fs::equivalent() (injected as \c PathComparator). There might
51 /// be zero or more entries with the same matching suffix length that are
52 /// equivalent to the input file. Three cases are distinguished:
53 /// 0 equivalent files: Continue with the next suffix length.
54 /// 1 equivalent file: Best match found, return it.
55 /// >1 equivalent files: Match is ambiguous, return error.
57 public:
58  FileMatchTrie();
59 
60  /// Construct a new \c FileMatchTrie with the given \c PathComparator.
61  ///
62  /// The \c FileMatchTrie takes ownership of 'Comparator'. Used for testing.
63  FileMatchTrie(PathComparator* Comparator);
64 
65  ~FileMatchTrie();
66 
67  /// Insert a new absolute path. Relative paths are ignored.
68  void insert(StringRef NewPath);
69 
70  /// Finds the corresponding file in this trie.
71  ///
72  /// Returns file name stored in this trie that is equivalent to 'FileName'
73  /// according to 'Comparator', if it can be uniquely identified. If there
74  /// are no matches an empty \c StringRef is returned. If there are ambiguous
75  /// matches, an empty \c StringRef is returned and a corresponding message
76  /// written to 'Error'.
77  StringRef findEquivalent(StringRef FileName,
78  raw_ostream &Error) const;
79 
80 private:
81  FileMatchTrieNode *Root;
82  std::unique_ptr<PathComparator> Comparator;
83 };
84 
85 } // namespace tooling
86 } // namespace clang
87 
88 #endif // LLVM_CLANG_TOOLING_FILEMATCHTRIE_H
virtual ~PathComparator()=default
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
llvm::Error Error
A trie to efficiently match against the entries of the compilation database in order of matching suff...
Definition: FileMatchTrie.h:56
virtual bool equivalent(StringRef FileA, StringRef FileB) const =0
Dataflow Directional Tag Classes.
A node of the FileMatchTrie.