clang  7.0.0svn
FileMatchTrie.cpp
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1 //===- FileMatchTrie.cpp --------------------------------------------------===//
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 contains the implementation of a FileMatchTrie.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "llvm/ADT/StringMap.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/Support/FileSystem.h"
18 #include "llvm/Support/Path.h"
19 #include "llvm/Support/raw_ostream.h"
20 #include <string>
21 #include <vector>
22 
23 using namespace clang;
24 using namespace tooling;
25 
26 namespace {
27 
28 /// Default \c PathComparator using \c llvm::sys::fs::equivalent().
29 struct DefaultPathComparator : public PathComparator {
30  bool equivalent(StringRef FileA, StringRef FileB) const override {
31  return FileA == FileB || llvm::sys::fs::equivalent(FileA, FileB);
32  }
33 };
34 
35 } // namespace
36 
37 namespace clang {
38 namespace tooling {
39 
40 /// A node of the \c FileMatchTrie.
41 ///
42 /// Each node has storage for up to one path and a map mapping a path segment to
43 /// child nodes. The trie starts with an empty root node.
45 public:
46  /// Inserts 'NewPath' into this trie. \c ConsumedLength denotes
47  /// the number of \c NewPath's trailing characters already consumed during
48  /// recursion.
49  ///
50  /// An insert of a path
51  /// 'p'starts at the root node and does the following:
52  /// - If the node is empty, insert 'p' into its storage and abort.
53  /// - If the node has a path 'p2' but no children, take the last path segment
54  /// 's' of 'p2', put a new child into the map at 's' an insert the rest of
55  /// 'p2' there.
56  /// - Insert a new child for the last segment of 'p' and insert the rest of
57  /// 'p' there.
58  ///
59  /// An insert operation is linear in the number of a path's segments.
60  void insert(StringRef NewPath, unsigned ConsumedLength = 0) {
61  // We cannot put relative paths into the FileMatchTrie as then a path can be
62  // a postfix of another path, violating a core assumption of the trie.
63  if (llvm::sys::path::is_relative(NewPath))
64  return;
65  if (Path.empty()) {
66  // This is an empty leaf. Store NewPath and return.
67  Path = NewPath;
68  return;
69  }
70  if (Children.empty()) {
71  // This is a leaf, ignore duplicate entry if 'Path' equals 'NewPath'.
72  if (NewPath == Path)
73  return;
74  // Make this a node and create a child-leaf with 'Path'.
75  StringRef Element(llvm::sys::path::filename(
76  StringRef(Path).drop_back(ConsumedLength)));
77  Children[Element].Path = Path;
78  }
79  StringRef Element(llvm::sys::path::filename(
80  StringRef(NewPath).drop_back(ConsumedLength)));
81  Children[Element].insert(NewPath, ConsumedLength + Element.size() + 1);
82  }
83 
84  /// Tries to find the node under this \c FileMatchTrieNode that best
85  /// matches 'FileName'.
86  ///
87  /// If multiple paths fit 'FileName' equally well, \c IsAmbiguous is set to
88  /// \c true and an empty string is returned. If no path fits 'FileName', an
89  /// empty string is returned. \c ConsumedLength denotes the number of
90  /// \c Filename's trailing characters already consumed during recursion.
91  ///
92  /// To find the best matching node for a given path 'p', the
93  /// \c findEquivalent() function is called recursively for each path segment
94  /// (back to front) of 'p' until a node 'n' is reached that does not ..
95  /// - .. have children. In this case it is checked
96  /// whether the stored path is equivalent to 'p'. If yes, the best match is
97  /// found. Otherwise continue with the parent node as if this node did not
98  /// exist.
99  /// - .. a child matching the next path segment. In this case, all children of
100  /// 'n' are an equally good match for 'p'. All children are of 'n' are found
101  /// recursively and their equivalence to 'p' is determined. If none are
102  /// equivalent, continue with the parent node as if 'n' didn't exist. If one
103  /// is equivalent, the best match is found. Otherwise, report and ambigiuity
104  /// error.
105  StringRef findEquivalent(const PathComparator& Comparator,
106  StringRef FileName,
107  bool &IsAmbiguous,
108  unsigned ConsumedLength = 0) const {
109  if (Children.empty()) {
110  if (Comparator.equivalent(StringRef(Path), FileName))
111  return StringRef(Path);
112  return {};
113  }
114  StringRef Element(llvm::sys::path::filename(FileName.drop_back(
115  ConsumedLength)));
116  llvm::StringMap<FileMatchTrieNode>::const_iterator MatchingChild =
117  Children.find(Element);
118  if (MatchingChild != Children.end()) {
119  StringRef Result = MatchingChild->getValue().findEquivalent(
120  Comparator, FileName, IsAmbiguous,
121  ConsumedLength + Element.size() + 1);
122  if (!Result.empty() || IsAmbiguous)
123  return Result;
124  }
125  std::vector<StringRef> AllChildren;
126  getAll(AllChildren, MatchingChild);
127  StringRef Result;
128  for (const auto &Child : AllChildren) {
129  if (Comparator.equivalent(Child, FileName)) {
130  if (Result.empty()) {
131  Result = Child;
132  } else {
133  IsAmbiguous = true;
134  return {};
135  }
136  }
137  }
138  return Result;
139  }
140 
141 private:
142  /// Gets all paths under this FileMatchTrieNode.
143  void getAll(std::vector<StringRef> &Results,
144  llvm::StringMap<FileMatchTrieNode>::const_iterator Except) const {
145  if (Path.empty())
146  return;
147  if (Children.empty()) {
148  Results.push_back(StringRef(Path));
149  return;
150  }
151  for (llvm::StringMap<FileMatchTrieNode>::const_iterator
152  It = Children.begin(), E = Children.end();
153  It != E; ++It) {
154  if (It == Except)
155  continue;
156  It->getValue().getAll(Results, Children.end());
157  }
158  }
159 
160  // The stored absolute path in this node. Only valid for leaf nodes, i.e.
161  // nodes where Children.empty().
162  std::string Path;
163 
164  // The children of this node stored in a map based on the next path segment.
165  llvm::StringMap<FileMatchTrieNode> Children;
166 };
167 
168 } // namespace tooling
169 } // namespace clang
170 
172  : Root(new FileMatchTrieNode), Comparator(new DefaultPathComparator()) {}
173 
175  : Root(new FileMatchTrieNode), Comparator(Comparator) {}
176 
178  delete Root;
179 }
180 
181 void FileMatchTrie::insert(StringRef NewPath) {
182  Root->insert(NewPath);
183 }
184 
185 StringRef FileMatchTrie::findEquivalent(StringRef FileName,
186  raw_ostream &Error) const {
187  if (llvm::sys::path::is_relative(FileName)) {
188  Error << "Cannot resolve relative paths";
189  return {};
190  }
191  bool IsAmbiguous = false;
192  StringRef Result = Root->findEquivalent(*Comparator, FileName, IsAmbiguous);
193  if (IsAmbiguous)
194  Error << "Path is ambiguous";
195  return Result;
196 }
void insert(StringRef NewPath)
Insert a new absolute path. Relative paths are ignored.
void insert(StringRef NewPath, unsigned ConsumedLength=0)
Inserts &#39;NewPath&#39; into this trie.
virtual bool equivalent(StringRef FileA, StringRef FileB) const =0
Dataflow Directional Tag Classes.
A node of the FileMatchTrie.
StringRef findEquivalent(StringRef FileName, raw_ostream &Error) const
Finds the corresponding file in this trie.
StringRef findEquivalent(const PathComparator &Comparator, StringRef FileName, bool &IsAmbiguous, unsigned ConsumedLength=0) const
Tries to find the node under this FileMatchTrieNode that best matches &#39;FileName&#39;. ...