Add folder/file Composite example

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/structural/composite/AddressablePath.java

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+package pl.mperor.lab.java.design.pattern.structural.composite;
+
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public abstract class AddressablePath implements Nameable {
+
+    private final String name;
+    private Nameable parent;
+
+    protected AddressablePath(String name) {
+        this.name = name;
+    }
+
+    protected void setParent(Nameable parent) {
+        this.parent = parent;
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        if (parent == null) {
+            return name;
+        }
+
+        return Stream.of(parent.toString(), name)
+                .collect(Collectors.joining("/"));
+    }
+
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/structural/composite/File.java

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+package pl.mperor.lab.java.design.pattern.structural.composite;
+
+public class File extends AddressablePath {
+
+    protected File(String name) {
+        super(name);
+    }
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/structural/composite/Folder.java

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+package pl.mperor.lab.java.design.pattern.structural.composite;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.function.Predicate;
+
+public final class Folder extends AddressablePath {
+
+    private final AddressablePath[] paths;
+
+    public Folder(String name, AddressablePath... paths) {
+        super(name);
+        this.paths = paths;
+        for (AddressablePath path : paths) {
+            path.setParent(this);
+        }
+    }
+
+    public List<String> find(Predicate<String> nameMatcher) {
+        List<String> result = new ArrayList<>();
+
+        Arrays.stream(paths)
+                .filter(path -> nameMatcher.test(path.getName()))
+                .map(Object::toString)
+                .forEach(result::add);
+
+        Arrays.stream(paths)
+                .filter(Folder.class::isInstance)
+                .map(Folder.class::cast)
+                .map(folder -> folder.find(nameMatcher))
+                .flatMap(Collection::stream)
+                .forEach(result::add);
+
+        return result;
+    }
+
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/structural/composite/Nameable.java

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+package pl.mperor.lab.java.design.pattern.structural.composite;
+
+public interface Nameable {
+    String getName();
+}

DesignPatterns/src/test/java/pl/mperor/lab/java/design/pattern/structural/composite/FolderCompositeTest.java

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+package pl.mperor.lab.java.design.pattern.structural.composite;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+class FolderCompositeTest {
+
+    @Test
+    public void shouldAllowToSearchNames() {
+        var root = new Folder("root",
+                new Folder("css", new File("main.css"), new File("user.css")),
+                new Folder("js", new File("main.js"), new File("user.js")),
+                new Folder("fonts", new File("monospace.ttf")),
+                new Folder("images", new File("logo.png")),
+                new File("index.html")
+        );
+
+        Assertions.assertEquals(List.of("root/css", "root/css/main.css", "root/css/user.css"),
+                root.find(name -> name.contains("css")));
+        Assertions.assertEquals(List.of("root/js/main.js", "root/js/user.js"),
+                root.find(name -> name.endsWith(".js")));
+        Assertions.assertEquals(List.of(), root.find(name -> name.endsWith(".exe")));
+    }
+
+}