Proof of concept for support of editor config in Java formatters

org.eclipse.jdt.core.manipulation/common/org/eclipse/jdt/internal/ui/preferences/formatter/FormatterProfileManagerCore.java

@@ -14,20 +14,92 @@
  *******************************************************************************/
 package org.eclipse.jdt.internal.ui.preferences.formatter;
 
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
+import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences;
 
+import org.eclipse.core.resources.IFile;
+import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.ProjectScope;
 
 import org.eclipse.jdt.core.IJavaProject;
 import org.eclipse.jdt.core.manipulation.JavaManipulation;
 
 public class FormatterProfileManagerCore {
+	private static final String EDITORCONFIG= ".editorconfig"; //$NON-NLS-1$
+
 	public final static String FORMATTER_SETTINGS_VERSION= "formatter_settings_version"; //$NON-NLS-1$
 
 	public static Map<String, String> getProjectSettings(IJavaProject javaProject) {
+		Map<String, String> map= computeDefaults(javaProject);
+		IPath editorConfig= findEditorConfig(javaProject.getProject());
+		if (editorConfig != null) {
+			try {
+				List<String> lines= Files.readAllLines(editorConfig.toFile().toPath());
+				String tabChar= getSetting(lines, "indent_style"); //$NON-NLS-1$
+				if (tabChar != null) {
+					System.out.println("Override tab char from editor config with value: " + tabChar); //$NON-NLS-1$
+					map.put("org.eclipse.jdt.core.formatter.tabulation.char", tabChar); //$NON-NLS-1$
+				}
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+		return map;
+	}
+
+	private static String getSetting(List<String> lines, String property) {
+		boolean found= false;
+		for (String line : lines) {
+			if (line.equals("[*]") || line.equals("[*.java]")) { //$NON-NLS-1$ //$NON-NLS-2$
+				found= true;
+			} else if (line.startsWith("[")) { //$NON-NLS-1$
+				found= false;
+			} else if (found) {
+				if (line.startsWith(property)) {
+					String[] split= line.split("="); //$NON-NLS-1$
+					return split[1].trim();
+				}
+			}
+		}
+		return null;
+	}
+
+	private static IPath findEditorConfig(IProject project) {
+		IFile projectFile= project.getFile(EDITORCONFIG);
+		if (projectFile.exists()) {
+			return projectFile.getLocation();
+		}
+		IPath location= project.getLocation();
+		if (location == null) {
+			return null;
+		}
+		File file= location.toFile();
+		return findEditorConfig(file.getParentFile(), project.getWorkspace().getRoot().getLocation().toFile());
+	}
+
+	private static IPath findEditorConfig(File folder, File workspaceRoot) {
+		if (folder == null || folder.equals(workspaceRoot)) {
+			return null;
+		}
+		File file= new File(folder, EDITORCONFIG);
+		if (file.exists()) {
+			return IPath.fromFile(file);
+		}
+		if (new File(folder, ".git").isDirectory()) { //$NON-NLS-1$
+			//do not search beyond boundaries of git workingcopy
+			return null;
+		}
+		return findEditorConfig(folder.getParentFile(), workspaceRoot);
+	}
+
+	protected static Map<String, String> computeDefaults(IJavaProject javaProject) {
 		Map<String, String> options= new HashMap<>(javaProject.getOptions(true));
 		IEclipsePreferences prefs= new ProjectScope(javaProject.getProject()).getNode(JavaManipulation.getPreferenceNodeId());
 		if (prefs == null)