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TNotifyLink.h
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1// @(#)root/base:$Id$
2// Author: Philippe Canal 2019
3
4/*************************************************************************
5 * Copyright (C) 1995-2019, Rene Brun and Fons Rademakers. *
6 * All rights reserved. *
7 * *
8 * For the licensing terms see $ROOTSYS/LICENSE. *
9 * For the list of contributors see $ROOTSYS/README/CREDITS. *
10 *************************************************************************/
11
12#ifndef ROOT_TNotifyLink
13#define ROOT_TNotifyLink
14
15#include <TObject.h>
16#include <TError.h> // for R__ASSERT
17
18/** \class TNotifyLink
19\ingroup Base
20
21Links multiple listeners to be notified on TChain file changes.
22
23Neither TChain::SetNotify() nor this TNotifyLink take ownership of the object to be notified.
24
25eg.
26```
27auto notify = new TNotifyLink(object, fChain->GetNotify());
28fChain->SetNotify(notify);
29```
30**/
31
32class TNotifyLinkBase : public TObject {
33protected:
35 TObject *fNext = nullptr;
36
37public:
38 // TTree status bits
40 kLinked = BIT(11) // Used when the TNotifyLink is connected to a TTree.
41 };
42
43 void Clear(Option_t * /*option*/ ="") {
44 auto current = this;
45 do {
46 auto next = dynamic_cast<TNotifyLinkBase*>(fNext);
47 current->ResetBit(kLinked);
48 current->fPrevious = nullptr;
49 current->fNext = nullptr;
50 current = next;
51 } while(current);
52 }
53
54 template <class Notifier>
55 void PrependLink(Notifier &notifier) {
57
58 fNext = notifier.GetNotify();
59 if (auto link = dynamic_cast<TNotifyLinkBase*>(fNext)) {
60 link->fPrevious = this;
61 }
62 notifier.SetNotify(this);
63 }
64
65 template <class Notifier>
66 void RemoveLink(Notifier &notifier) {
68
69 if (notifier.GetNotify() == this) {
70 R__ASSERT(fPrevious == nullptr && "The TNotifyLink head node should not have a previous element.");
71 notifier.SetNotify(fNext);
72 } else if (fPrevious) {
74 }
75 if (auto link = dynamic_cast<TNotifyLinkBase*>(fNext)) {
76 link->fPrevious = fPrevious;
77 }
78 fPrevious = nullptr;
79 fNext = nullptr;
80 }
81
83 return TestBit(kLinked);
84 }
85
87};
88
89template <class Type>
91private:
93
94public:
95 TNotifyLink(Type *current) : fCurrent(current) {}
96
97 // Call Notify on the current and next object.
98 Bool_t Notify() override
99 {
100 auto result = fCurrent ? fCurrent->Notify() : kTRUE;
101 if (fNext) result &= fNext->Notify();
102 return result;
103 }
104
106};
107
108#endif // ROOT_TNotifyLink
bool Bool_t
Definition: RtypesCore.h:63
const Bool_t kTRUE
Definition: RtypesCore.h:100
const char Option_t
Definition: RtypesCore.h:66
#define ClassDef(name, id)
Definition: Rtypes.h:325
#define BIT(n)
Definition: Rtypes.h:85
#define R__ASSERT(e)
Definition: TError.h:118
TNotifyLinkBase * fPrevious
Definition: TNotifyLink.h:34
TObject * fNext
Definition: TNotifyLink.h:35
void RemoveLink(Notifier &notifier)
Definition: TNotifyLink.h:66
void PrependLink(Notifier &notifier)
Definition: TNotifyLink.h:55
Bool_t IsLinked()
Definition: TNotifyLink.h:82
void Clear(Option_t *="")
Definition: TNotifyLink.h:43
Mother of all ROOT objects.
Definition: TObject.h:37
virtual Bool_t Notify()
This method must be overridden to handle object notification.
Definition: TObject.cxx:508
R__ALWAYS_INLINE Bool_t TestBit(UInt_t f) const
Definition: TObject.h:187
void SetBit(UInt_t f, Bool_t set)
Set or unset the user status bits as specified in f.
Definition: TObject.cxx:696
void ResetBit(UInt_t f)
Definition: TObject.h:186
Type
enumeration specifying the integration types.