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1 /////////////////////////////////////////////////////////////////////////////
2 // Name: garbagec.cpp
3 // Purpose: Garbage collection algorithm for optimizing refresh.
4 // Author: Aleksandras Gluchovas
5 // Modified by:
6 // Created: 18/10/98
7 // RCS-ID: $Id$
8 // Copyright: (c) Aleksandras Gluchovas
9 // Licence: wxWindows licence
10 /////////////////////////////////////////////////////////////////////////////
11
12
13 #ifdef __GNUG__
14 #pragma implementation "garbagec.h"
15 #endif
16
17 // For compilers that support precompilation, includes "wx/wx.h".
18 #include "wx/wxprec.h"
19
20 #ifdef __BORLANDC__
21 #pragma hdrstop
22 #endif
23
24
25 #ifndef WX_PRECOMP
26 #include "wx/wx.h"
27 #endif
28
29 #include "wx/fl/garbagec.h"
30
31 /***** Implementation for class GarbageCollector *****/
32
33 inline static GCItem& node_to_item( wxNode* pNode )
34 {
35 return *( (GCItem*)(pNode->GetData()) );
36 }
37
38 GarbageCollector::~GarbageCollector()
39 {
40 Reset();
41 }
42
43 /*** GC alg. helpers ***/
44
45 void GarbageCollector::DestroyItemList( wxList& lst )
46 {
47 wxNode* pNode = lst.GetFirst();
48
49 while( pNode )
50 {
51 delete &node_to_item( pNode );
52
53 pNode = pNode->GetNext();
54 }
55
56 lst.Clear();
57 }
58
59 wxNode* GarbageCollector::FindItemNode( void* pForObj )
60 {
61 wxNode* pNode = mAllNodes.GetFirst();
62
63 while( pNode )
64 {
65 if ( node_to_item( pNode ).mpObj == pForObj )
66
67 return pNode;
68
69 pNode = pNode->GetNext();
70 }
71
72 int avoidCompilerWarning = 0;
73 wxASSERT(avoidCompilerWarning); // DBG:: item should be present
74
75 return 0;
76 }
77
78 wxNode* GarbageCollector::FindReferenceFreeItemNode()
79 {
80 wxNode* pNode = mAllNodes.GetFirst();
81
82 while( pNode )
83 {
84 if ( node_to_item( pNode ).mRefs.GetCount() == 0 )
85
86 return pNode;
87
88 pNode = pNode->GetNext();
89 }
90
91 return 0;
92 }
93
94 void GarbageCollector::RemoveReferencesToNode( wxNode* pItemNode )
95 {
96 wxNode* pNode = mAllNodes.GetFirst();
97
98 while( pNode )
99 {
100 wxList& refLst = node_to_item( pNode ).mRefs;
101 wxNode* pRefNode = refLst.GetFirst();
102
103 while( pRefNode )
104 {
105 if ( pRefNode->GetData() == (wxObject*)pItemNode )
106 {
107 wxNode* pNext = pRefNode->GetNext();
108
109 refLst.DeleteNode( pRefNode );
110
111 pRefNode = pNext;
112
113 continue;
114 }
115 else pRefNode = pRefNode->GetNext();
116 }
117
118 pNode = pNode->GetNext();
119 }
120 }
121
122 void GarbageCollector::ResolveReferences()
123 {
124 wxNode* pNode = mAllNodes.GetFirst();
125
126 while( pNode )
127 {
128 GCItem& item = node_to_item( pNode );
129
130 wxNode* pRefNode = item.mRefs.GetFirst();
131
132 while( pRefNode )
133 {
134 pRefNode->SetData( (wxObject*) FindItemNode( (void*)pRefNode->GetData() ) );
135
136 pRefNode = pRefNode->GetNext();
137 }
138
139 pNode = pNode->GetNext();
140 }
141 }
142
143 void GarbageCollector::AddObject( void* pObj, int WXUNUSED(refCnt) )
144 {
145 // FOR NOW:: initial ref-count is not used
146
147 GCItem* pItem = new GCItem();
148
149 pItem->mpObj = pObj;
150
151 mAllNodes.Append( (wxObject*) pItem );
152 }
153
154 void GarbageCollector::AddDependency( void* pObj, void* pDependsOnObj )
155 {
156 node_to_item( FindItemNode( pObj ) ).mRefs.Append( (wxObject*)pDependsOnObj );
157 }
158
159 /*** GC alg. implementation ***/
160
161 void GarbageCollector::ArrangeCollection()
162 {
163 ResolveReferences();
164
165 do
166 {
167 // find node, which does not depend on anything
168
169 wxNode* pItemNode = FindReferenceFreeItemNode();
170
171 if ( pItemNode )
172 {
173 // append it to the list, where items are contained
174 // in the increasing order of dependencies
175
176 mRegularLst.Append( pItemNode->GetData() );
177
178 mAllNodes.DeleteNode( pItemNode );
179
180 // remove references to this current "least-dependent" node
181 // from reference lists of all the other nodes
182
183 RemoveReferencesToNode( pItemNode );
184 }
185 else
186 {
187 // otherwise, what is left - all nodes, which
188 // are involved into cycled chains (rings)
189
190 wxNode* pNode = mAllNodes.GetFirst();
191
192 while( pNode )
193 {
194 mCycledLst.Append( pNode->GetData() );
195
196 pNode = pNode->GetNext();
197 }
198
199 mAllNodes.Clear();
200 break;
201 }
202
203 // continue search for "least-dependent" nodes
204
205 } while(1);
206 }
207
208 wxList& GarbageCollector::GetRegularObjects()
209 {
210 return mRegularLst;
211 }
212
213 wxList& GarbageCollector::GetCycledObjects()
214 {
215 return mCycledLst;
216 }
217
218 void GarbageCollector::Reset()
219 {
220 DestroyItemList( mAllNodes );
221 DestroyItemList( mRegularLst );
222 DestroyItemList( mCycledLst );
223 }
224