Better "isLastChild" detection algorithm

Author: ComputerDaddyGuy

ROADMAP.md

@@ -5,8 +5,8 @@
 - [x] Regroup all formatting work under single "LineFormatter"
 - [x] Builder with options (depth symbols, emoji, child limit)
 - [x] Unit tests, using @TempDir
+- [x] Better "isLastChild" detection algorithm
 - [ ] Max depth options
-- [ ] Better "isLast" detection algorithm
 - [ ] Unify dir-in-a-row into a single entry option
 
 ## Other ideas

…typrinter/visitor/ChildVisitCounter.java …yprinter/visitor/ChildVisitRegister.javasrc/main/java/io/github/computerdaddyguy/jfiletreeprettyprinter/visitor/ChildVisitCounter.java renamed to src/main/java/io/github/computerdaddyguy/jfiletreeprettyprinter/visitor/ChildVisitRegister.java src/main/java/io/github/computerdaddyguy/jfiletreeprettyprinter/visitor/ChildVisitCounter.java renamed to src/main/java/io/github/computerdaddyguy/jfiletreeprettyprinter/visitor/ChildVisitRegister.java

@@ -5,21 +5,21 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
-import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.function.Function;
 import org.jspecify.annotations.NullMarked;
 
 @NullMarked
-class ChildVisitCounter {
+class ChildVisitRegister {
 
 	private final Function<Path, Integer> childrenLimitFunction;
 	private final List<ChildVisitCounterRecord> records;
 
-	public ChildVisitCounter(Function<Path, Integer> childrenLimitFunction) {
+	public ChildVisitRegister(Function<Path, Integer> childrenLimitFunction) {
 		this.childrenLimitFunction = childrenLimitFunction;
-		this.records = new ArrayList<ChildVisitCounter.ChildVisitCounterRecord>();
+		this.records = new ArrayList<ChildVisitRegister.ChildVisitCounterRecord>();
 	}
 
 	public void enterNewDirectory(Path dir) {
@@ -29,8 +29,8 @@ public void enterNewDirectory(Path dir) {
 		records.add(newRecord);
 	}
 
-	private Set<Path> listChildren(Path dir) {
-		var children = new HashSet<Path>();
+	private LinkedHashSet<Path> listChildren(Path dir) {
+		var children = new LinkedHashSet<Path>();
 		try (var stream = Files.newDirectoryStream(dir)) {
 			for (Path child : stream) {
 				children.add(child);
@@ -48,6 +48,13 @@ public void registerChildVisitInCurrentDir(Path visited) {
 		records.getLast().registerChildVisit(visited);
 	}
 
+	public boolean isLastChildInCurrentDir(Path path) {
+		if (records.isEmpty()) {
+			return true;
+		}
+		return records.getLast().notVisited.isEmpty() || records.getLast().notVisited.getLast().equals(path);
+	}
+
 	public void exitCurrentDirectory() {
 		records.removeLast();
 	}
@@ -67,13 +74,13 @@ public boolean hasSomeNotVisitedChildren() {
 	private class ChildVisitCounterRecord {
 
 		private final int maxChildVisitCount;
-		private Set<Path> notVisited;
-		private Set<Path> alreadyVisited;
+		private LinkedHashSet<Path> notVisited;
+		private LinkedHashSet<Path> alreadyVisited;
 
-		ChildVisitCounterRecord(int maxChildVisitCount, Set<Path> childrenInDir) {
+		ChildVisitCounterRecord(int maxChildVisitCount, LinkedHashSet<Path> childrenInDir) {
 			this.maxChildVisitCount = maxChildVisitCount;
 			this.notVisited = childrenInDir;
-			this.alreadyVisited = new HashSet<Path>();
+			this.alreadyVisited = new LinkedHashSet<Path>();
 		}
 
 		void registerChildVisit(Path visited) {

src/main/java/io/github/computerdaddyguy/jfiletreeprettyprinter/visitor/DefaultFileTreePrettyPrintVisitor.java

@@ -2,7 +2,6 @@
 
 import io.github.computerdaddyguy.jfiletreeprettyprinter.PrettyPrintOptions;
 import io.github.computerdaddyguy.jfiletreeprettyprinter.visitor.renderer.LineRenderer;
-import java.io.File;
 import java.io.IOException;
 import java.nio.file.FileVisitResult;
 import java.nio.file.Path;
@@ -17,15 +16,15 @@ class DefaultFileTreePrettyPrintVisitor implements FileTreePrettyPrintVisitor {
 
 	private StringBuilder buff;
 	private Depth depth;
-	private ChildVisitCounter counter;
+	private ChildVisitRegister register;
 
 	public DefaultFileTreePrettyPrintVisitor(PrettyPrintOptions options, LineRenderer lineRenderer) {
 		super();
 		this.lineRenderer = lineRenderer;
 
 		this.buff = new StringBuilder();
 		this.depth = new Depth();
-		this.counter = new ChildVisitCounter(options.getChildrenLimitFunction());
+		this.register = new ChildVisitRegister(options.getChildrenLimitFunction());
 	}
 
 	@Override
@@ -36,7 +35,7 @@ public String getResult() {
 	@Override
 	public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
 		// COUNTER
-		if (counter.exceedsCurrentLimit()) {
+		if (register.exceedsCurrentLimit()) {
 			return FileVisitResult.SKIP_SIBLINGS;
 		}
 
@@ -48,19 +47,19 @@ public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) th
 		depth = depth.append(DepthSymbol.NON_LAST_FILE); // assume not last until proven otherwise
 
 		// COUNTER
-		counter.registerChildVisitInCurrentDir(dir);
-		counter.enterNewDirectory(dir);
+		register.registerChildVisitInCurrentDir(dir);
+		register.enterNewDirectory(dir);
 
 		return FileVisitResult.CONTINUE;
 	}
 
 	@Override
 	public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
 		// COUNTER
-		if (counter.exceedsCurrentLimit()) {
+		if (register.exceedsCurrentLimit()) {
 			return FileVisitResult.SKIP_SIBLINGS;
 		}
-		counter.registerChildVisitInCurrentDir(file);
+		register.registerChildVisitInCurrentDir(file);
 
 		// DEPTH
 		updateDepth(file);
@@ -95,13 +94,13 @@ public FileVisitResult postVisitDirectory(Path dir, @Nullable IOException exc) t
 		depth = depth.pop();
 
 		// COUNTER
-		var limitReached = counter.hasSomeNotVisitedChildren();
+		var limitReached = register.hasSomeNotVisitedChildren();
 		if (limitReached) {
 			depth = depth.append(DepthSymbol.LAST_FILE);
-			appendNewLine(lineRenderer.renderLimitReached(depth, counter.notVisitedInCurrentDir()));
+			appendNewLine(lineRenderer.renderLimitReached(depth, register.notVisitedInCurrentDir()));
 			depth = depth.pop();
 		}
-		counter.exitCurrentDirectory();
+		register.exitCurrentDirectory();
 
 		if (limitReached) {
 			return FileVisitResult.SKIP_SIBLINGS;
@@ -114,17 +113,11 @@ private void updateDepth(Path path) {
 			return;
 		}
 
-		var isLast = isLastChild(path);
+		var isLast = register.isLastChildInCurrentDir(path);
 		depth = depth.pop();
 		depth = depth.append(isLast ? DepthSymbol.LAST_FILE : DepthSymbol.NON_LAST_FILE);
 	}
 
-	private boolean isLastChild(Path path) {
-		Path parent = path.getParent();
-		File[] siblings = parent.toFile().listFiles();
-		return siblings != null && siblings[siblings.length - 1].toPath().equals(path);
-	}
-
 	private void appendNewLine(@Nullable String str) {
 		if (str != null) {
 			if (buff.length() > 0) {