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add Visitor example
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‎README.md

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@@ -9,6 +9,7 @@ I'm adding new samples from time to time.
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5. Singleton (EagerInitialization,as Enum,LazyInitialization,StaticBlockInitialization,ThreadSafe)
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6. State
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7. Strategy
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8. Visitor
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# Contribute
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‎src/io/github/mcaliman/patterns/visitor/Document.java

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/*
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The MIT License (MIT)
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Copyright (c) 2015 Massimo Caliman
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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package io.github.mcaliman.patterns.visitor;
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import java.io.File;
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/**
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* @author Massimo Caliman
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*/
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public class Document implements Node {
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private final File file;
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public Document(File file) {
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this.file = file;
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}
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public String getName() {
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return file.getName();
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}
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@Override
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public void accept(Visitor v) {
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v.visit(this);
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}
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}

‎src/io/github/mcaliman/patterns/visitor/Folder.java

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/*
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The MIT License (MIT)
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Copyright (c) 2015 Massimo Caliman
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
11+
furnished to do so, subject to the following conditions:
12+
13+
The above copyright notice and this permission notice shall be included in all
14+
copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19+
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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package io.github.mcaliman.patterns.visitor;
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import java.io.File;
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/**
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* @author Massimo Caliman
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*/
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public class Folder implements Node {
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private final File directory;
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public Folder(File directory) {
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this.directory = directory;
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}
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@Override
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public void accept(Visitor v) {
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v.visit(this);
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}
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public String getName() {
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return directory.getName();
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}
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public Node[] getChildren() {
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File[] files = directory.listFiles();
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Node[] nodes = new Node[files.length];
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for (int i = 0; i < files.length; i++) {
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nodes[i] = files[i].isDirectory() ? new Folder(files[i]) : new Document(files[i]);
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}
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return nodes;
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}
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}

‎src/io/github/mcaliman/patterns/visitor/Node.java

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/*
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The MIT License (MIT)
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Copyright (c) 2015 Massimo Caliman
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10+
copies of the Software, and to permit persons to whom the Software is
11+
furnished to do so, subject to the following conditions:
12+
13+
The above copyright notice and this permission notice shall be included in all
14+
copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17+
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18+
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19+
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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package io.github.mcaliman.patterns.visitor;
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/**
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* @author Massimo Caliman
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*/
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public interface Node {
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void accept(Visitor v);
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}

‎src/io/github/mcaliman/patterns/visitor/NullVisitor.java

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/*
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The MIT License (MIT)
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Copyright (c) 2015 Massimo Caliman
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Permission is hereby granted, free of charge, to any person obtaining a copy
7+
of this software and associated documentation files (the "Software"), to deal
8+
in the Software without restriction, including without limitation the rights
9+
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10+
copies of the Software, and to permit persons to whom the Software is
11+
furnished to do so, subject to the following conditions:
12+
13+
The above copyright notice and this permission notice shall be included in all
14+
copies or substantial portions of the Software.
15+
16+
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17+
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18+
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19+
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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package io.github.mcaliman.patterns.visitor;
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/**
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* @author Massimo Caliman
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*/
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public class NullVisitor implements Visitor {
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@Override
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public void visit(Document file) {
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//do nothing
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}
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@Override
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public void visit(Folder directory) {
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Node[] children = directory.getChildren();
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for (Node file : children) {
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file.accept(this);
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}
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}
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}

‎src/io/github/mcaliman/patterns/visitor/PrintVisitor.java

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/*
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The MIT License (MIT)
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Copyright (c) 2015 Massimo Caliman
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Permission is hereby granted, free of charge, to any person obtaining a copy
7+
of this software and associated documentation files (the "Software"), to deal
8+
in the Software without restriction, including without limitation the rights
9+
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10+
copies of the Software, and to permit persons to whom the Software is
11+
furnished to do so, subject to the following conditions:
12+
13+
The above copyright notice and this permission notice shall be included in all
14+
copies or substantial portions of the Software.
15+
16+
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17+
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18+
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19+
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20+
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21+
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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package io.github.mcaliman.patterns.visitor;
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import static java.lang.System.out;
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/**
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* @author Massimo Caliman
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*/
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public class PrintVisitor implements Visitor {
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private int level = 0;//livello di profondità per l'indentazione
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@Override
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public void visit(Document document) {
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for (int i = 0; i < level; i++) {
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out.print(" ");
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}
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out.println("Document: " + document.getName());
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}
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@Override
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public void visit(Folder folder) {
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for (int i = 0; i < level; i++) {
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out.print(" ");
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}
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out.println("Folder: " + folder.getName());
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level++;
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Node[] children = folder.getChildren();
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for (Node node : children) {
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node.accept(this);
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}
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level--;
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}
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}

‎src/io/github/mcaliman/patterns/visitor/Visitor.java

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/*
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The MIT License (MIT)
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Copyright (c) 2015 Massimo Caliman
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6+
Permission is hereby granted, free of charge, to any person obtaining a copy
7+
of this software and associated documentation files (the "Software"), to deal
8+
in the Software without restriction, including without limitation the rights
9+
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10+
copies of the Software, and to permit persons to whom the Software is
11+
furnished to do so, subject to the following conditions:
12+
13+
The above copyright notice and this permission notice shall be included in all
14+
copies or substantial portions of the Software.
15+
16+
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17+
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18+
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19+
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20+
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21+
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22+
SOFTWARE.
23+
*/
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package io.github.mcaliman.patterns.visitor;
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/**
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* @author Massimo Caliman
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*/
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public interface Visitor {
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void visit(Document node);
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void visit(Folder node);
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}

‎src/io/github/mcaliman/patterns/visitor/VisitorPatternJavaExamples.java

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/*
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The MIT License (MIT)
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Copyright (c) 2015 Massimo Caliman
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6+
Permission is hereby granted, free of charge, to any person obtaining a copy
7+
of this software and associated documentation files (the "Software"), to deal
8+
in the Software without restriction, including without limitation the rights
9+
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10+
copies of the Software, and to permit persons to whom the Software is
11+
furnished to do so, subject to the following conditions:
12+
13+
The above copyright notice and this permission notice shall be included in all
14+
copies or substantial portions of the Software.
15+
16+
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17+
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18+
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19+
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20+
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21+
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22+
SOFTWARE.
23+
*/
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package io.github.mcaliman.patterns.visitor;
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import java.io.File;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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* @author Massimo Caliman
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*/
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public class VisitorPatternJavaExamples {
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private static final Logger LOG = Logger.getLogger(VisitorPatternJavaExamples.class.getName());
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public static void main(String[] args) {
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Folder node = new Folder(new File("/home/mcaliman/Dropbox"));
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/*LOG.log(Level.INFO,"test PrintVisitor");
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LOG.log(Level.INFO,"=================");
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*/
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node.accept(new PrintVisitor());
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LOG.log(Level.INFO, "test NullVisitor");
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LOG.log(Level.INFO, "=================");
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node.accept(new NullVisitor());
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}
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}

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