Option: Line extension (=additional text after the file name)

Author: ComputerDaddyGuy

CHANGELOG.md

@@ -5,15 +5,20 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+---
 ## [0.0.4] - Unreleased
 
+### Added
+- Line extension: append any String after a path (comment, file details, etc.)
+
 ### Changed
 - Filtering: moved to options
+- Compact dirs: root dir is now never compacted
 
 ### Removed
 - Error handling: exceptions are now thrown instead of being handled by the renderer
 
-
+---
 ## [0.0.3] - 2025-09-21
 
 ### Added
@@ -25,14 +30,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Sorting: option method `withFileSort` renamed in `sort`
 - Child limit: various renaming and refactor
 
-
+---
 ## [0.0.2] - 2025-09-16
 
 ### Added
 - Option: sorting files and directories
 - 39 new default files & extension mappings for emojis
 
-
+---
 ## [0.0.1] - 2025-09-14
 
 ### Added

README.md

@@ -15,6 +15,7 @@
 - Limit displayed children (fixed value or dynamically)
 - Compact directory chains
 - Maximum depth
+- Custom line extension (comment, file details, etc.)
 - Various styles for tree rendering
 
 > [!CAUTION]
@@ -90,6 +91,7 @@ base/
 * [Max depth](#max-depth)
 * [Sorting](#sorting)
 * [Filtering](#filtering)
+* [Line extension](#line-extension)
 
 ## Tree format
 Choose between different tree formats.
@@ -296,6 +298,49 @@ filtering/
 └─ file_A.java
 ```
 
+## Line extension
+You can extend each displayed path with additional information by providing a custom `Function<Path, String>`.
+This is useful to annotate your tree with comments, display file sizes, or add domain-specific notes.
+
+The function receives the current path and returns an optional string to append.
+If the function returns `null`, nothing is added.
+
+```java
+// Example: LineExtension.java
+Function<Path, String> lineExtension = path -> {
+	if (PathUtils.isDirectory(path) && PathUtils.hasName(path, "api")) {
+		return "\t\t\t// All API code: controllers, etc.";
+	}
+	if (PathUtils.isDirectory(path) && PathUtils.hasName(path, "domain")) {
+		return "\t\t\t// All domain code: value objects, etc.";
+	}
+	if (PathUtils.isDirectory(path) && PathUtils.hasName(path, "infra")) {
+		return "\t\t\t// All infra code: database, email service, etc.";
+	}
+	if (PathUtils.isFile(path) && PathUtils.hasName(path, "application.properties")) {
+		return "\t// Config file";
+	}
+	return null;
+};
+var prettyPrinter = FileTreePrettyPrinter.builder()
+	.customizeOptions(options -> options.withLineExtension(lineExtension))
+	.build();
+```
+```
+line_extension/
+└─ src/
+   └─ main/
+      ├─ java/
+      │  ├─ api/			// All API code: controllers, etc.
+      │  │  └─ Controller.java
+      │  ├─ domain/			// All domain code: value objects, etc.
+      │  │  └─ ValueObject.java
+      │  └─ infra/			// All infra code: database, email service, etc.
+      │     └─ Repository.java
+      └─ resources/
+         └─ application.properties	// Config file
+```
+
 # Changelog
 See [CHANGELOG.md](CHANGELOG.md) for released versions.
 

ROADMAP.md

@@ -20,18 +20,14 @@
 ## To do
 - [x] Use Github wiki to document options instead of readme
 - [x] Jacoco coverage report
-- [ ] Option: Line extension (=additional text after the file name)
-- [ ] Option: Filename decorator
+- [x] Option: Line extension (=additional text after the file name)
 
-## Backlog
+## Backlog / To analyze / To implement if requested
+- [ ] More `PathPredicates` functions!
 - [ ] Option: custom tree format
 - [ ] Option: custom emojis
-- [ ] Option: color
 - [ ] Refactor unit tests (custom assert?)
-- [ ] More `PathPredicates` functions!
-
-## Abandoned
-These ideas will likely not been implemented because they do not align with JFileTreePrettyPrint vision:
-- File attributes LineRenderer (size, author, createAt, etc.)
-- Print optional legend for symlink/other file types symbols (at the end of the tree)
-- Follow symlink option
+- [ ] Option: color
+- [ ] Option: Filename decorator
+- [ ] Option: Follow symlink
+- [ ] Advanced line extension function (file size, author, timestamps, etc. )

src/example/java/io/github/computerdaddyguy/jfiletreeprettyprinter/example/LineExtension.java

@@ -0,0 +1,33 @@
+package io.github.computerdaddyguy.jfiletreeprettyprinter.example;
+
+import io.github.computerdaddyguy.jfiletreeprettyprinter.FileTreePrettyPrinter;
+import io.github.computerdaddyguy.jfiletreeprettyprinter.PathUtils;
+import java.nio.file.Path;
+import java.util.function.Function;
+
+public class LineExtension {
+
+	public static void main(String[] args) {
+		Function<Path, String> lineExtension = path -> {
+			if (PathUtils.isDirectory(path) && PathUtils.hasName(path, "api")) {
+				return "\t\t\t// All API code: controllers, etc.";
+			}
+			if (PathUtils.isDirectory(path) && PathUtils.hasName(path, "domain")) {
+				return "\t\t\t// All domain code: value objects, etc.";
+			}
+			if (PathUtils.isDirectory(path) && PathUtils.hasName(path, "infra")) {
+				return "\t\t\t// All infra code: database, email service, etc.";
+			}
+			if (PathUtils.isFile(path) && PathUtils.hasName(path, "application.properties")) {
+				return "\t// Config file";
+			}
+			return null;
+		};
+		var prettyPrinter = FileTreePrettyPrinter.builder()
+			.customizeOptions(options -> options.withLineExtension(lineExtension))
+			.build();
+		var tree = prettyPrinter.prettyPrint("src/example/resources/line_extension");
+		System.out.println(tree);
+	}
+
+}

src/example/resources/line_extension/src/main/java/api/Controller.java

@@ -5,6 +5,7 @@
 import java.nio.file.Path;
 import java.util.Comparator;
 import java.util.Objects;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.ToIntFunction;
 import org.jspecify.annotations.NullMarked;
@@ -313,9 +314,37 @@ public Predicate<Path> pathFilter() {
 	
 	 * @param filter	The filter, <code>null</code> to disable filtering
 	 */
-	public PrettyPrintOptions filter(Predicate<Path> filter) {
+	public PrettyPrintOptions filter(@Nullable Predicate<Path> filter) {
 		this.pathFilter = filter;
 		return this;
 	}
 
+	// ---------- Line extension ----------
+
+	@Nullable
+	private Function<Path, String> lineExtension;
+
+	@Override
+	@Nullable
+	public Function<Path, String> getLineExtension() {
+		return lineExtension;
+	}
+
+	/**
+	 * Sets a custom line extension function that appends additional text to each
+	 * printed line, allowing you to customize the display of files or directories.
+	 * <p>
+	 * Typical use cases include adding comments, showing file sizes, or displaying metadata.
+	 * <p>
+	 * The function receives the current {@link Path} displayed on the line
+	 * and returns an optional string to be appended.
+	 * If the function returns {@code null}, nothing is added.
+	 * 
+	 * @param lineExtension	the custom line extension function, or {@code null} to disable
+	 */
+	public PrettyPrintOptions withLineExtension(@Nullable Function<Path, String> lineExtension) {
+		this.lineExtension = lineExtension;
+		return this;
+	}
+
 }

src/example/resources/line_extension/src/main/java/domain/ValueObject.java

@@ -26,60 +26,76 @@ public DefaultTreeEntryRenderer(RenderingOptions options) {
 
 	@Override
 	public String renderTree(TreeEntry entry) {
-		var depth = Depth.createNewEmpty();
-		var buff = new StringBuilder();
-		renderTree(entry, depth, buff);
-		return buff.toString();
+		return renderTree(entry, Depth.createNewEmpty());
 	}
 
-	public void renderTree(TreeEntry entry, Depth depth, StringBuilder buff) {
-		switch (entry) {
-			case TreeEntry.DirectoryEntry dirEntry -> renderDirectory(buff, depth, dirEntry, List.of(dirEntry.getDir()));
-			case TreeEntry.FileEntry fileEntry -> renderFile(buff, depth, fileEntry);
-			case TreeEntry.SkippedChildrenEntry skippedChildrenEntry -> renderSkippedChildrenEntry(buff, depth, skippedChildrenEntry);
-			case TreeEntry.MaxDepthReachEntry maxDepthReachEntry -> renderMaxDepthReachEntry(buff, depth, maxDepthReachEntry);
-		}
+	private String renderTree(TreeEntry entry, Depth depth) {
+		return switch (entry) {
+			case TreeEntry.DirectoryEntry dirEntry -> renderDirectory(depth, dirEntry, List.of(dirEntry.getDir()));
+			case TreeEntry.FileEntry fileEntry -> renderFile(depth, fileEntry);
+			case TreeEntry.SkippedChildrenEntry skippedChildrenEntry -> renderSkippedChildrenEntry(depth, skippedChildrenEntry);
+			case TreeEntry.MaxDepthReachEntry maxDepthReachEntry -> renderMaxDepthReachEntry(depth, maxDepthReachEntry);
+		};
 	}
 
-	private void renderDirectory(StringBuilder buff, Depth depth, DirectoryEntry dirEntry, List<Path> compactPaths) {
+	private String renderDirectory(Depth depth, DirectoryEntry dirEntry, List<Path> compactPaths) {
 
 		if (options.areCompactDirectoriesUsed()
+			&& !depth.isRoot()
 			&& dirEntry.getEntries().size() == 1
 			&& dirEntry.getEntries().get(0) instanceof DirectoryEntry childDirEntry) {
-			var newCompactPaths = new ArrayList<>(compactPaths);
-			newCompactPaths.add(childDirEntry.getDir());
-			renderDirectory(buff, depth, childDirEntry, newCompactPaths);
-			return;
+
+			var extension = computeLineExtension(dirEntry.getDir());
+			if (extension.isEmpty()) {
+				var newCompactPaths = new ArrayList<>(compactPaths);
+				newCompactPaths.add(childDirEntry.getDir());
+				return renderDirectory(depth, childDirEntry, newCompactPaths);
+			}
 		}
 
-		buff.append(lineRenderer.renderDirectoryBegin(depth, dirEntry, compactPaths));
+		var line = lineRenderer.renderDirectoryBegin(depth, dirEntry, compactPaths);
+		line += computeLineExtension(dirEntry.getDir());
 
 		var childIt = dirEntry.getEntries().iterator();
 
 		if (childIt.hasNext()) {
-			buff.append('\n');
+			line += "\n";
 		}
 
+		var childLines = new StringBuilder();
+
 		while (childIt.hasNext()) {
 			var childEntry = childIt.next();
 			var childDepth = depth.append(childIt.hasNext() ? DepthSymbol.NON_LAST_FILE : DepthSymbol.LAST_FILE);
-			renderTree(childEntry, childDepth, buff);
+			childLines.append(renderTree(childEntry, childDepth));
 			if (childIt.hasNext()) {
-				buff.append('\n');
+				childLines.append('\n');
 			}
 		}
+
+		return line + childLines.toString();
+	}
+
+	private String computeLineExtension(Path path) {
+		if (options.getLineExtension() == null) {
+			return "";
+		}
+		var extension = options.getLineExtension().apply(path);
+		return extension == null ? "" : extension;
 	}
 
-	private void renderFile(StringBuilder buff, Depth depth, FileEntry fileEntry) {
-		buff.append(lineRenderer.renderFile(depth, fileEntry));
+	private String renderFile(Depth depth, FileEntry fileEntry) {
+		var line = lineRenderer.renderFile(depth, fileEntry);
+		line += computeLineExtension(fileEntry.getFile());
+		return line;
 	}
 
-	private void renderSkippedChildrenEntry(StringBuilder buff, Depth depth, SkippedChildrenEntry skippedChildrenEntry) {
-		buff.append(lineRenderer.renderChildLimitReached(depth, skippedChildrenEntry));
+	private String renderSkippedChildrenEntry(Depth depth, SkippedChildrenEntry skippedChildrenEntry) {
+		return lineRenderer.renderChildLimitReached(depth, skippedChildrenEntry);
 	}
 
-	private void renderMaxDepthReachEntry(StringBuilder buff, Depth depth, MaxDepthReachEntry maxDepthReachEntry) {
-		buff.append(lineRenderer.renderMaxDepthReached(depth, maxDepthReachEntry));
+	private String renderMaxDepthReachEntry(Depth depth, MaxDepthReachEntry maxDepthReachEntry) {
+		return lineRenderer.renderMaxDepthReached(depth, maxDepthReachEntry);
 	}
 
 }