clang  12.0.0git
ParentMapContext.h
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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"
19 
20 namespace clang {
21 class DynTypedNodeList;
22 
24 public:
26 
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 
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;
66 
67 private:
68  ASTContext &ASTCtx;
69  class ParentMap;
71  std::unique_ptr<ParentMap> Parents;
72 };
73 
75  ParentMapContext &Ctx;
77 
78 public:
80  : Ctx(ASTCtx.getParentMapContext()) {
81  TK = Ctx.getTraversalKind();
82  if (ScopeTK)
83  Ctx.setTraversalKind(*ScopeTK);
84  }
85 
87 };
88 
89 /// Container for either a single DynTypedNode or for an ArrayRef to
90 /// DynTypedNode. For use with ParentMap.
92  llvm::AlignedCharArrayUnion<DynTypedNode, ArrayRef<DynTypedNode>> Storage;
93  bool IsSingleNode;
94 
95 public:
96  DynTypedNodeList(const DynTypedNode &N) : IsSingleNode(true) {
97  new (Storage.buffer) DynTypedNode(N);
98  }
99 
101  new (Storage.buffer) ArrayRef<DynTypedNode>(A);
102  }
103 
104  const DynTypedNode *begin() const {
105  if (!IsSingleNode)
106  return reinterpret_cast<const ArrayRef<DynTypedNode> *>(Storage.buffer)
107  ->begin();
108  return reinterpret_cast<const DynTypedNode *>(Storage.buffer);
109  }
110 
111  const DynTypedNode *end() const {
112  if (!IsSingleNode)
113  return reinterpret_cast<const ArrayRef<DynTypedNode> *>(Storage.buffer)
114  ->end();
115  return reinterpret_cast<const DynTypedNode *>(Storage.buffer) + 1;
116  }
117 
118  size_t size() const { return end() - begin(); }
119  bool empty() const { return begin() == end(); }
120 
121  const DynTypedNode &operator[](size_t N) const {
122  assert(N < size() && "Out of bounds!");
123  return *(begin() + N);
124  }
125 };
126 
127 template <typename NodeT>
129  return getParents(DynTypedNode::create(Node));
130 }
131 
132 template <typename NodeT>
134  return getParentMapContext().getParents(Node);
135 }
136 
137 template <>
139  return getParentMapContext().getParents(Node);
140 }
141 
142 } // namespace clang
143 
144 #endif
Defines the clang::ASTContext interface.
::clang::DynTypedNode DynTypedNode
TraversalKind
Defines how we descend a level in the AST when we pass through expressions.
Definition: ASTTypeTraits.h:39
const DynTypedNode * end() const
static DynTypedNode create(const T &Node)
Creates a DynTypedNode from Node.
TraversalKind getTraversalKind() const
Will traverse all child nodes.
Definition: ASTTypeTraits.h:41
TraversalKind Traversal
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:174
DynTypedNodeList getParents(const NodeT &Node)
Forwards to get node parents from the ParentMapContext.
DynTypedNodeList getParents(const NodeT &Node)
Returns the parents of the given node (within the traversal scope).
TraversalKindScope(ASTContext &ASTCtx, llvm::Optional< TraversalKind > ScopeTK)
This represents one expression.
Definition: Expr.h:110
DynTypedNode Node
const Expr * traverseIgnored(const Expr *E) const
#define false
Definition: stdbool.h:17
const DynTypedNode & operator[](size_t N) const
A dynamically typed AST node container.
Dataflow Directional Tag Classes.
const DynTypedNode * begin() const
void clear()
Clear parent maps.
Container for either a single DynTypedNode or for an ArrayRef to DynTypedNode.
ParentMapContext(ASTContext &Ctx)
DynTypedNodeList(ArrayRef< DynTypedNode > A)
void setTraversalKind(TraversalKind TK)
#define true
Definition: stdbool.h:16
DynTypedNodeList(const DynTypedNode &N)