1 //===-- Baton.h -------------------------------------------------*- 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 #ifndef LLDB_UTILITY_BATON_H
10 #define LLDB_UTILITY_BATON_H
11 
12 #include "lldb/lldb-enumerations.h"
13 #include "lldb/lldb-public.h"
14 
15 #include "llvm/Support/raw_ostream.h"
16 
17 #include <memory>
18 
19 namespace lldb_private {
20 class Stream;
21 }
22 
23 namespace lldb_private {
24 
25 /// \class Baton Baton.h "lldb/Core/Baton.h"
26 /// A class designed to wrap callback batons so they can cleanup
27 ///        any acquired resources
28 ///
29 /// This class is designed to be used by any objects that have a callback
30 /// function that takes a baton where the baton might need to
31 /// free/delete/close itself.
32 ///
33 /// The default behavior is to not free anything. Subclasses can free any
34 /// needed resources in their destructors.
35 class Baton {
36 public:
37   Baton() = default;
38   virtual ~Baton() = default;
39 
40   virtual void *data() = 0;
41 
42   virtual void GetDescription(llvm::raw_ostream &s,
43                               lldb::DescriptionLevel level,
44                               unsigned indentation) const = 0;
45 };
46 
47 class UntypedBaton : public Baton {
48 public:
49   UntypedBaton(void *Data) : m_data(Data) {}
50   ~UntypedBaton() override {
51     // The default destructor for an untyped baton does NOT attempt to clean up
52     // anything in m_data.
53   }
54 
55   void *data() override { return m_data; }
56   void GetDescription(llvm::raw_ostream &s, lldb::DescriptionLevel level,
57                       unsigned indentation) const override;
58 
59   void *m_data; // Leave baton public for easy access
60 };
61 
62 template <typename T> class TypedBaton : public Baton {
63 public:
64   explicit TypedBaton(std::unique_ptr<T> Item) : Item(std::move(Item)) {}
65 
66   T *getItem() { return Item.get(); }
67   const T *getItem() const { return Item.get(); }
68 
69   void *data() override { return Item.get(); }
70   void GetDescription(llvm::raw_ostream &s, lldb::DescriptionLevel level,
71                       unsigned indentation) const override {}
72 
73 protected:
74   std::unique_ptr<T> Item;
75 };
76 
77 } // namespace lldb_private
78 
79 #endif // LLDB_UTILITY_BATON_H
80