clang 10.0.0git

FileMatchTrie.cpp
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1 //===- FileMatchTrie.cpp --------------------------------------------------===//
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 contains the implementation of a FileMatchTrie.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "clang/Tooling/FileMatchTrie.h"
14 #include "llvm/ADT/StringMap.h"
15 #include "llvm/ADT/StringRef.h"
16 #include "llvm/Support/FileSystem.h"
17 #include "llvm/Support/Path.h"
18 #include "llvm/Support/raw_ostream.h"
19 #include <string>
20 #include <vector>
21
22 using namespace clang;
23 using namespace tooling;
24
25 namespace {
26
27 /// Default \c PathComparator using \c llvm::sys::fs::equivalent().
28 struct DefaultPathComparator : public PathComparator {
29 bool equivalent(StringRef FileA, StringRef FileB) const override {
30 return FileA == FileB || llvm::sys::fs::equivalent(FileA, FileB);
31 }
32 };
33
34 } // namespace
35
36 namespace clang {
37 namespace tooling {
38
39 /// A node of the \c FileMatchTrie.
40 ///
41 /// Each node has storage for up to one path and a map mapping a path segment to
42 /// child nodes. The trie starts with an empty root node.
43 class FileMatchTrieNode {
44 public:
45 /// Inserts 'NewPath' into this trie. \c ConsumedLength denotes
46 /// the number of \c NewPath's trailing characters already consumed during
47 /// recursion.
48 ///
49 /// An insert of a path
50 /// 'p'starts at the root node and does the following:
51 /// - If the node is empty, insert 'p' into its storage and abort.
52 /// - If the node has a path 'p2' but no children, take the last path segment
53 /// 's' of 'p2', put a new child into the map at 's' an insert the rest of
54 /// 'p2' there.
55 /// - Insert a new child for the last segment of 'p' and insert the rest of
56 /// 'p' there.
57 ///
58 /// An insert operation is linear in the number of a path's segments.
59 void insert(StringRef NewPath, unsigned ConsumedLength = 0) {
60 // We cannot put relative paths into the FileMatchTrie as then a path can be
61 // a postfix of another path, violating a core assumption of the trie.
62 if (llvm::sys::path::is_relative(NewPath))
63 return;
64 if (Path.empty()) {
65 // This is an empty leaf. Store NewPath and return.
66 Path = NewPath;
67 return;
68 }
69 if (Children.empty()) {
70 // This is a leaf, ignore duplicate entry if 'Path' equals 'NewPath'.
71 if (NewPath == Path)
72 return;
73 // Make this a node and create a child-leaf with 'Path'.
74 StringRef Element(llvm::sys::path::filename(
75 StringRef(Path).drop_back(ConsumedLength)));
76 Children[Element].Path = Path;
77 }
78 StringRef Element(llvm::sys::path::filename(
79 StringRef(NewPath).drop_back(ConsumedLength)));
80 Children[Element].insert(NewPath, ConsumedLength + Element.size() + 1);
81 }
82
83 /// Tries to find the node under this \c FileMatchTrieNode that best
84 /// matches 'FileName'.
85 ///
86 /// If multiple paths fit 'FileName' equally well, \c IsAmbiguous is set to
87 /// \c true and an empty string is returned. If no path fits 'FileName', an
88 /// empty string is returned. \c ConsumedLength denotes the number of
89 /// \c Filename's trailing characters already consumed during recursion.
90 ///
91 /// To find the best matching node for a given path 'p', the
92 /// \c findEquivalent() function is called recursively for each path segment
93 /// (back to front) of 'p' until a node 'n' is reached that does not ..
94 /// - .. have children. In this case it is checked
95 /// whether the stored path is equivalent to 'p'. If yes, the best match is
96 /// found. Otherwise continue with the parent node as if this node did not
97 /// exist.
98 /// - .. a child matching the next path segment. In this case, all children of
99 /// 'n' are an equally good match for 'p'. All children are of 'n' are found
100 /// recursively and their equivalence to 'p' is determined. If none are
101 /// equivalent, continue with the parent node as if 'n' didn't exist. If one
102 /// is equivalent, the best match is found. Otherwise, report and ambigiuity
103 /// error.
104 StringRef findEquivalent(const PathComparator& Comparator,
105 StringRef FileName,
106 bool &IsAmbiguous,
107 unsigned ConsumedLength = 0) const {
108 if (Children.empty()) {
109 if (Comparator.equivalent(StringRef(Path), FileName))
110 return StringRef(Path);
111 return {};
112 }
113 StringRef Element(llvm::sys::path::filename(FileName.drop_back(
114 ConsumedLength)));
115 llvm::StringMap<FileMatchTrieNode>::const_iterator MatchingChild =
116 Children.find(Element);
117 if (MatchingChild != Children.end()) {
118 StringRef Result = MatchingChild->getValue().findEquivalent(
119 Comparator, FileName, IsAmbiguous,
120 ConsumedLength + Element.size() + 1);
121 if (!Result.empty() || IsAmbiguous)
122 return Result;
123 }
124 std::vector<StringRef> AllChildren;
125 getAll(AllChildren, MatchingChild);
126 StringRef Result;
127 for (const auto &Child : AllChildren) {
128 if (Comparator.equivalent(Child, FileName)) {
129 if (Result.empty()) {
130 Result = Child;
131 } else {
132 IsAmbiguous = true;
133 return {};
134 }
135 }
136 }
137 return Result;
138 }
139
140 private:
141 /// Gets all paths under this FileMatchTrieNode.
142 void getAll(std::vector<StringRef> &Results,
143 llvm::StringMap<FileMatchTrieNode>::const_iterator Except) const {
144 if (Path.empty())
145 return;
146 if (Children.empty()) {
147 Results.push_back(StringRef(Path));
148 return;
149 }
150 for (llvm::StringMap<FileMatchTrieNode>::const_iterator
151 It = Children.begin(), E = Children.end();
152 It != E; ++It) {
153 if (It == Except)
154 continue;
155 It->getValue().getAll(Results, Children.end());
156 }
157 }
158
159 // The stored absolute path in this node. Only valid for leaf nodes, i.e.
160 // nodes where Children.empty().
161 std::string Path;
162
163 // The children of this node stored in a map based on the next path segment.
164 llvm::StringMap<FileMatchTrieNode> Children;
165 };
166
167 } // namespace tooling
168 } // namespace clang
169
170 FileMatchTrie::FileMatchTrie()
171 : Root(new FileMatchTrieNode), Comparator(new DefaultPathComparator()) {}
172
173 FileMatchTrie::FileMatchTrie(PathComparator *Comparator)
174 : Root(new FileMatchTrieNode), Comparator(Comparator) {}
175
176 FileMatchTrie::~FileMatchTrie() {
177 delete Root;
178 }
179
180 void FileMatchTrie::insert(StringRef NewPath) {
181 Root->insert(NewPath);
182 }
183
184 StringRef FileMatchTrie::findEquivalent(StringRef FileName,
185 raw_ostream &Error) const {
186 if (llvm::sys::path::is_relative(FileName)) {
187 Error << "Cannot resolve relative paths";
188 return {};
189 }
190 bool IsAmbiguous = false;
191 StringRef Result = Root->findEquivalent(*Comparator, FileName, IsAmbiguous);
192 if (IsAmbiguous)
193 Error << "Path is ambiguous";
194 return Result;
195 }
clang::tooling::FileMatchTrie::insert
void insert(StringRef NewPath)
Insert a new absolute path. Relative paths are ignored.
Definition: FileMatchTrie.cpp:180
clang::tooling::FileMatchTrieNode::insert
void insert(StringRef NewPath, unsigned ConsumedLength=0)
Inserts &#39;NewPath&#39; into this trie.
Definition: FileMatchTrie.cpp:59
FileMatchTrie.h
clang::tooling::FileMatchTrie::~FileMatchTrie
~FileMatchTrie()
Definition: FileMatchTrie.cpp:176
clang::tooling::PathComparator::equivalent
virtual bool equivalent(StringRef FileA, StringRef FileB) const =0
clang::tooling::FileMatchTrie::FileMatchTrie
FileMatchTrie()
Definition: FileMatchTrie.cpp:170
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:21
clang::tooling::FileMatchTrieNode
A node of the FileMatchTrie.
Definition: FileMatchTrie.cpp:43
clang::tooling::PathComparator
Definition: FileMatchTrie.h:26
clang::tooling::FileMatchTrie::findEquivalent
StringRef findEquivalent(StringRef FileName, raw_ostream &Error) const
Finds the corresponding file in this trie.
Definition: FileMatchTrie.cpp:184
clang::tooling::FileMatchTrieNode::findEquivalent
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;. ...
Definition: FileMatchTrie.cpp:104