clang  10.0.0svn
ASTDiff.h
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1 //===- ASTDiff.h - AST differencing API -----------------------*- C++ -*- -===//
2 //
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file specifies an interface that can be used to compare C++ syntax
11 // trees.
12 //
13 // We use the gumtree algorithm which combines a heuristic top-down search that
14 // is able to match large subtrees that are equivalent, with an optimal
15 // algorithm to match small subtrees.
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #ifndef LLVM_CLANG_TOOLING_ASTDIFF_ASTDIFF_H
20 #define LLVM_CLANG_TOOLING_ASTDIFF_ASTDIFF_H
21 
23 
24 namespace clang {
25 namespace diff {
26 
27 enum ChangeKind {
29  Delete, // (Src): delete node Src.
30  Update, // (Src, Dst): update the value of node Src to match Dst.
31  Insert, // (Src, Dst, Pos): insert Src as child of Dst at offset Pos.
32  Move, // (Src, Dst, Pos): move Src to be a child of Dst at offset Pos.
33  UpdateMove // Same as Move plus Update.
34 };
35 
36 /// Represents a Clang AST node, alongside some additional information.
37 struct Node {
39  int Depth, Height, Shift = 0;
43 
45  StringRef getTypeLabel() const;
46  bool isLeaf() const { return Children.empty(); }
49 };
50 
51 class ASTDiff {
52 public:
53  ASTDiff(SyntaxTree &Src, SyntaxTree &Dst, const ComparisonOptions &Options);
54  ~ASTDiff();
55 
56  // Returns the ID of the node that is mapped to the given node in SourceTree.
57  NodeId getMapped(const SyntaxTree &SourceTree, NodeId Id) const;
58 
59  class Impl;
60 
61 private:
62  std::unique_ptr<Impl> DiffImpl;
63 };
64 
65 /// SyntaxTree objects represent subtrees of the AST.
66 /// They can be constructed from any Decl or Stmt.
67 class SyntaxTree {
68 public:
69  /// Constructs a tree from a translation unit.
70  SyntaxTree(ASTContext &AST);
71  /// Constructs a tree from any AST node.
72  template <class T>
74  : TreeImpl(std::make_unique<Impl>(this, Node, AST)) {}
75  SyntaxTree(SyntaxTree &&Other) = default;
76  ~SyntaxTree();
77 
78  const ASTContext &getASTContext() const;
79  StringRef getFilename() const;
80 
81  int getSize() const;
82  NodeId getRootId() const;
84  PreorderIterator begin() const;
85  PreorderIterator end() const;
86 
87  const Node &getNode(NodeId Id) const;
88  int findPositionInParent(NodeId Id) const;
89 
90  // Returns the starting and ending offset of the node in its source file.
91  std::pair<unsigned, unsigned> getSourceRangeOffsets(const Node &N) const;
92 
93  /// Serialize the node attributes to a string representation. This should
94  /// uniquely distinguish nodes of the same kind. Note that this function just
95  /// returns a representation of the node value, not considering descendants.
96  std::string getNodeValue(NodeId Id) const;
97  std::string getNodeValue(const Node &Node) const;
98 
99  class Impl;
100  std::unique_ptr<Impl> TreeImpl;
101 };
102 
104  /// During top-down matching, only consider nodes of at least this height.
105  int MinHeight = 2;
106 
107  /// During bottom-up matching, match only nodes with at least this value as
108  /// the ratio of their common descendants.
109  double MinSimilarity = 0.5;
110 
111  /// Whenever two subtrees are matched in the bottom-up phase, the optimal
112  /// mapping is computed, unless the size of either subtrees exceeds this.
113  int MaxSize = 100;
114 
115  bool StopAfterTopDown = false;
116 
117  /// Returns false if the nodes should never be matched.
118  bool isMatchingAllowed(const Node &N1, const Node &N2) const {
119  return N1.getType().isSame(N2.getType());
120  }
121 };
122 
123 } // end namespace diff
124 } // end namespace clang
125 
126 #endif
llvm::Optional< std::string > getQualifiedIdentifier() const
Definition: ASTDiff.cpp:692
NodeId Parent
Definition: ASTDiff.h:38
ast_type_traits::ASTNodeKind getType() const
Definition: ASTDiff.cpp:686
bool isSame(ASTNodeKind Other) const
Returns true if this and Other represent the same kind.
Definition: ASTTypeTraits.h:77
llvm::Optional< StringRef > getIdentifier() const
Definition: ASTDiff.cpp:700
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:160
Definition: Format.h:2327
Within a tree, this identifies a node by its preorder offset.
ast_type_traits::DynTypedNode ASTNode
Definition: ASTDiff.h:40
ChangeKind Change
Definition: ASTDiff.h:42
std::unique_ptr< Impl > TreeImpl
Definition: ASTDiff.h:99
NodeId RightMostDescendant
Definition: ASTDiff.h:38
int Id
Definition: ASTDiff.cpp:190
SyntaxTree(T *Node, ASTContext &AST)
Constructs a tree from any AST node.
Definition: ASTDiff.h:73
bool isLeaf() const
Definition: ASTDiff.h:46
StringRef getTypeLabel() const
Definition: ASTDiff.cpp:690
SyntaxTree objects represent subtrees of the AST.
Definition: ASTDiff.h:67
SmallVector< NodeId, 4 > Children
Definition: ASTDiff.h:41
bool isMatchingAllowed(const Node &N1, const Node &N2) const
Returns false if the nodes should never be matched.
Definition: ASTDiff.h:118
Dataflow Directional Tag Classes.
Represents the AST of a TranslationUnit.
Definition: ASTDiff.cpp:111
NodeId LeftMostDescendant
Definition: ASTDiff.h:38
A dynamically typed AST node container.
static Expected< DynTypedNode > getNode(const ast_matchers::BoundNodes &Nodes, StringRef ID)
Represents a Clang AST node, alongside some additional information.
Definition: ASTDiff.h:37