1//===- ParentMapContext.h - Map of parents using DynTypedNode -------*- 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// Similar to ParentMap.h, but generalizes to non-Stmt nodes, which can have
10// multiple parents.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_AST_PARENTMAPCONTEXT_H
15#define LLVM_CLANG_AST_PARENTMAPCONTEXT_H
16
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/ASTTypeTraits.h"
19
20namespace clang {
21class DynTypedNodeList;
22
23class ParentMapContext {
24public:
25  ParentMapContext(ASTContext &Ctx);
26
27  ~ParentMapContext();
28
29  /// Returns the parents of the given node (within the traversal scope).
30  ///
31  /// Note that this will lazily compute the parents of all nodes
32  /// and store them for later retrieval. Thus, the first call is O(n)
33  /// in the number of AST nodes.
34  ///
35  /// Caveats and FIXMEs:
36  /// Calculating the parent map over all AST nodes will need to load the
37  /// full AST. This can be undesirable in the case where the full AST is
38  /// expensive to create (for example, when using precompiled header
39  /// preambles). Thus, there are good opportunities for optimization here.
40  /// One idea is to walk the given node downwards, looking for references
41  /// to declaration contexts - once a declaration context is found, compute
42  /// the parent map for the declaration context; if that can satisfy the
43  /// request, loading the whole AST can be avoided. Note that this is made
44  /// more complex by statements in templates having multiple parents - those
45  /// problems can be solved by building closure over the templated parts of
46  /// the AST, which also avoids touching large parts of the AST.
47  /// Additionally, we will want to add an interface to already give a hint
48  /// where to search for the parents, for example when looking at a statement
49  /// inside a certain function.
50  ///
51  /// 'NodeT' can be one of Decl, Stmt, Type, TypeLoc,
52  /// NestedNameSpecifier or NestedNameSpecifierLoc.
53  template <typename NodeT> DynTypedNodeList getParents(const NodeT &Node);
54
55  DynTypedNodeList getParents(const DynTypedNode &Node);
56
57  /// Clear parent maps.
58  void clear();
59
60  TraversalKind getTraversalKind() const { return Traversal; }
61  void setTraversalKind(TraversalKind TK) { Traversal = TK; }
62
63  const Expr *traverseIgnored(const Expr *E) const;
64  Expr *traverseIgnored(Expr *E) const;
65  DynTypedNode traverseIgnored(const DynTypedNode &N) const;
66
67  class ParentMap;
68
69private:
70  ASTContext &ASTCtx;
71  TraversalKind Traversal = TK_AsIs;
72  std::unique_ptr<ParentMap> Parents;
73};
74
75class TraversalKindScope {
76  ParentMapContext &Ctx;
77  TraversalKind TK = TK_AsIs;
78
79public:
80  TraversalKindScope(ASTContext &ASTCtx, std::optional<TraversalKind> ScopeTK)
81      : Ctx(ASTCtx.getParentMapContext()) {
82    TK = Ctx.getTraversalKind();
83    if (ScopeTK)
84      Ctx.setTraversalKind(*ScopeTK);
85  }
86
87  ~TraversalKindScope() { Ctx.setTraversalKind(TK); }
88};
89
90/// Container for either a single DynTypedNode or for an ArrayRef to
91/// DynTypedNode. For use with ParentMap.
92class DynTypedNodeList {
93  union {
94    DynTypedNode SingleNode;
95    ArrayRef<DynTypedNode> Nodes;
96  };
97  bool IsSingleNode;
98
99public:
100  DynTypedNodeList(const DynTypedNode &N) : IsSingleNode(true) {
101    new (&SingleNode) DynTypedNode(N);
102  }
103
104  DynTypedNodeList(ArrayRef<DynTypedNode> A) : IsSingleNode(false) {
105    new (&Nodes) ArrayRef<DynTypedNode>(A);
106  }
107
108  const DynTypedNode *begin() const {
109    return !IsSingleNode ? Nodes.begin() : &SingleNode;
110  }
111
112  const DynTypedNode *end() const {
113    return !IsSingleNode ? Nodes.end() : &SingleNode + 1;
114  }
115
116  size_t size() const { return end() - begin(); }
117  bool empty() const { return begin() == end(); }
118
119  const DynTypedNode &operator[](size_t N) const {
120    assert(N < size() && "Out of bounds!");
121    return *(begin() + N);
122  }
123};
124
125template <typename NodeT>
126inline DynTypedNodeList ParentMapContext::getParents(const NodeT &Node) {
127  return getParents(DynTypedNode::create(Node));
128}
129
130template <typename NodeT>
131inline DynTypedNodeList ASTContext::getParents(const NodeT &Node) {
132  return getParentMapContext().getParents(Node);
133}
134
135template <>
136inline DynTypedNodeList ASTContext::getParents(const DynTypedNode &Node) {
137  return getParentMapContext().getParents(Node);
138}
139
140} // namespace clang
141
142#endif
143