Reflection (#1085)

* index instead of reflection

* Update update.xml

CLAUDE.md

@@ -7,7 +7,7 @@ that file before editing anything under `diylc/`.
 
 | Path | Contents |
 | --- | --- |
-| `diylc/` | The application. Maven reactor with `diylc-core`, `diylc-library`, `diylc-swing`. This is where nearly all work happens. |
+| `diylc/` | The application. Maven reactor with `diylc-core`, `diylc-library`, `diylc-swing`, and the build-time `diylc-processor`. This is where nearly all work happens. |
 | `diylc-regression-data/` | Sample `.diy` projects plus reference PNG and netlist outputs used by the regression suite, and the historical reports. |
 | `diylc-server-api/` | PHP backend for cloud and collaboration features. Runs in an isolated environment on diy-fever.com and cannot be tested locally — do not modify unless explicitly asked. |
 | `snap/` | Snap packaging metadata. |

diylc/.claude/skills/add-component/SKILL.md

@@ -6,7 +6,8 @@ description: Add a new component type to the DIYLC library, or substantially mod
 # Adding a component to DIYLC
 
 Components live in `diylc-library/src/main/java/org/diylc/components/`. They are discovered at
-runtime by Reflections scanning `org.diylc` — **there is no registry to update**. A class becomes a
+runtime from a class index that `diylc-processor` writes at compile time — **there is no registry
+to update**. A class becomes a
 component by carrying `@ComponentDescriptor` and implementing `IDIYComponent` (in practice, by
 extending one of the abstract bases).
 

diylc/CLAUDE.md

@@ -15,14 +15,15 @@ if it compiles and works.
 
 ## Modules
 
-Maven reactor rooted at `diylc/pom.xml`, version `6.4.0`, three modules with a strict one-way
-dependency chain:
+Maven reactor rooted at `diylc/pom.xml`, version `6.4.0`, three application modules with a strict
+one-way dependency chain, plus a build-time annotation processor:
 
 | Module | Contains | Depends on |
 | --- | --- | --- |
 | `diylc-core` | Domain model, `Presenter`, rendering pipeline, messaging, serialization, netlist engine, annotations | — |
 | `diylc-library` | Concrete component classes, transformers, datasheets, legacy file parsers, component-aware analyzers | `diylc-core` |
 | `diylc-swing` | Swing shell, plugins, dialogs, editors, `DIYLCStarter` | `diylc-core`, `diylc-library` |
+| `diylc-processor` | `ServiceIndexProcessor`, run by `javac` over the three modules above; never on the runtime classpath | — |
 
 **`diylc-core` must never reference a concrete component type.** It knows components only through
 `IDIYComponent` and the annotations. If core logic seems to need knowledge of a specific component,
@@ -30,8 +31,11 @@ that knowledge belongs in `diylc-library` (an analyzer, a transformer, a parser)
 through a new interface in core that the component implements — look at
 `org.diylc.core.gerber.IGerberComponentSimple` for the established shape of that escape hatch.
 
-Component and plugin classes are discovered at runtime by Reflections scanning the `org.diylc`
-package (`ComponentProcessor`). There is no registry to update when adding a component.
+Components, netlist analyzers and parsers, legacy file parsers and auto-creators are discovered
+through a class index built at compile time: every concrete class implementing a type marked
+`@Indexed` (`IDIYComponent`, `INetlistAnalyzer`, ...) is listed under `META-INF/services/` by
+`diylc-processor`, and `ReflectionUtils.getIndexedClasses()` reads that back at startup. Nothing
+scans the classpath, and there is no registry to update when adding a component.
 
 ## Build and verify
 

diylc/diylc-core/pom.xml

@@ -19,6 +19,12 @@
     </properties>
     
     <dependencies>
+        <!-- Internal module dependencies -->
+        <dependency>
+            <groupId>org.diylc</groupId>
+            <artifactId>diylc-processor</artifactId>
+        </dependency>
+        
         <!-- Common dependencies from Maven Central -->
         <dependency>
             <groupId>log4j</groupId>
@@ -52,11 +58,6 @@
             <artifactId>jettison</artifactId>
             <version>1.5.4</version>
         </dependency>
-        <dependency>
-            <groupId>org.reflections</groupId>
-            <artifactId>reflections</artifactId>
-            <version>0.10.2</version>
-        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>

diylc/diylc-core/src/main/java/org/diylc/common/INetlistAnalyzer.java

@@ -24,11 +24,13 @@ package org.diylc.common;
 import java.util.List;
 import java.util.Set;
 
+import org.diylc.core.annotations.Indexed;
 import org.diylc.netlist.Netlist;
 import org.diylc.netlist.Node;
 import org.diylc.netlist.Summary;
 import org.diylc.netlist.TreeException;
 
+@Indexed
 public interface INetlistAnalyzer {
 
   /**   

diylc/diylc-core/src/main/java/org/diylc/core/IDIYComponent.java

@@ -29,6 +29,7 @@ import java.util.UUID;
 
 import org.diylc.core.annotations.ComponentDescriptor;
 import org.diylc.core.annotations.EditableProperty;
+import org.diylc.core.annotations.Indexed;
 
 /**
  * Interface for component instance. Implementation classes of this interface will be instantiated
@@ -47,6 +48,7 @@ import org.diylc.core.annotations.EditableProperty;
  * 
  * @param <T> type of component values, e.g. Resistance for resistors or String for transistors.
  */
+@Indexed
 public interface IDIYComponent<T> extends Serializable, Cloneable {
 
   public static final int CHASSIS = 1;

diylc/diylc-core/src/main/java/org/diylc/core/annotations/IAutoCreator.java

@@ -30,6 +30,7 @@ import org.diylc.core.IDIYComponent;
  * 
  * @author Branislav Stojkovic
  */
+@Indexed
 public interface IAutoCreator {
 
   /**

diylc/diylc-core/src/main/java/org/diylc/core/annotations/Indexed.java

@@ -0,0 +1,44 @@
+/*
+
+    DIY Layout Creator (DIYLC).
+    Copyright (c) 2009-2025 held jointly by the individual authors.
+
+    This file is part of DIYLC.
+
+    DIYLC is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    DIYLC is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DIYLC.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+package org.diylc.core.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.diylc.utils.ReflectionUtils;
+
+/**
+ * Marks a type whose concrete implementations are discovered at runtime. The
+ * {@code diylc-processor} annotation processor lists them under {@code META-INF/services} when
+ * the implementing module is compiled, and {@link ReflectionUtils#getIndexedClasses(Class)} reads
+ * that list back, so nothing has to scan the classpath. An implementation is picked up just by
+ * implementing the type; there is no registry to update.
+ *
+ * @author Branislav Stojkovic
+ */
+@Retention(RetentionPolicy.CLASS)
+@Target(ElementType.TYPE)
+public @interface Indexed {
+
+}

diylc/diylc-core/src/main/java/org/diylc/netlist/IGuitarDiagramAnalyzer.java

@@ -2,6 +2,9 @@ package org.diylc.netlist;
 
 import java.util.List;
 
+import org.diylc.core.annotations.Indexed;
+
+@Indexed
 public interface IGuitarDiagramAnalyzer {
 
   List<String> collectNotes(Netlist netlist);

diylc/diylc-core/src/main/java/org/diylc/netlist/INetlistParser.java

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.Map;
 
 import org.diylc.core.IDIYComponent;
+import org.diylc.core.annotations.Indexed;
 
 /*
  * 
@@ -41,6 +42,7 @@ import org.diylc.core.IDIYComponent;
  * <http://www.gnu.org/licenses/>.
  * 
  */
+@Indexed
 public interface INetlistParser {
 
   String getName();

diylc/diylc-core/src/main/java/org/diylc/presenter/ComponentIcon.java

@@ -0,0 +1,90 @@
+/*
+
+    DIY Layout Creator (DIYLC).
+    Copyright (c) 2009-2025 held jointly by the individual authors.
+
+    This file is part of DIYLC.
+
+    DIYLC is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    DIYLC is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DIYLC.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+package org.diylc.presenter;
+
+import java.awt.Component;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.image.BufferedImage;
+
+import javax.swing.Icon;
+import org.apache.log4j.Logger;
+
+import org.diylc.core.IDIYComponent;
+
+/**
+ * Toolbox icon of a component type. Drawing it means instantiating the component, so it is
+ * deferred until the icon is first painted rather than done for every type at startup.
+ *
+ * @author Branislav Stojkovic
+ */
+class ComponentIcon implements Icon {
+
+  private static final Logger LOG = Logger.getLogger(ComponentIcon.class);
+
+  private final Class<? extends IDIYComponent<?>> componentClass;
+  private BufferedImage image;
+
+  ComponentIcon(Class<? extends IDIYComponent<?>> componentClass) {
+    this.componentClass = componentClass;
+  }
+
+  @Override
+  public void paintIcon(Component c, Graphics g, int x, int y) {
+    if (image == null) {
+      image = drawImage();
+    }
+    g.drawImage(image, x, y, null);
+  }
+
+  @Override
+  public int getIconWidth() {
+    return Presenter.ICON_SIZE;
+  }
+
+  @Override
+  public int getIconHeight() {
+    return Presenter.ICON_SIZE;
+  }
+
+  private BufferedImage drawImage() {
+    BufferedImage image =
+        new BufferedImage(Presenter.ICON_SIZE, Presenter.ICON_SIZE, BufferedImage.TYPE_INT_ARGB);
+    Graphics2D g2d = image.createGraphics();
+    try {
+      IDIYComponent<?> componentInstance = componentClass.getDeclaredConstructor().newInstance();
+      g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+      g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
+      g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
+          RenderingHints.VALUE_INTERPOLATION_BICUBIC);
+      g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS,
+          RenderingHints.VALUE_FRACTIONALMETRICS_ON);
+      componentInstance.drawIcon(g2d, Presenter.ICON_SIZE, Presenter.ICON_SIZE);
+    } catch (Exception e) {
+      LOG.error("Error drawing component icon for " + componentClass.getName(), e);
+    } finally {
+      g2d.dispose();
+    }
+    return image;
+  }
+}

diylc/diylc-core/src/main/java/org/diylc/presenter/ComponentProcessor.java

@@ -21,19 +21,13 @@
 */
 package org.diylc.presenter;
 
-import java.awt.Graphics2D;
-import java.awt.Image;
-import java.awt.RenderingHints;
-import java.awt.image.BufferedImage;
 import java.lang.reflect.Method;
-import java.lang.reflect.Modifier;
 import java.util.*;
 import java.util.stream.Collectors;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
 import javax.swing.Icon;
-import javax.swing.ImageIcon;
 import org.apache.log4j.Logger;
 
 import org.diylc.common.ComponentType;
@@ -53,11 +47,7 @@ import org.diylc.core.annotations.EditableProperty;
 import org.diylc.core.annotations.KeywordPolicy;
 
 import org.diylc.lang.LangUtil;
-import org.reflections.Reflections;
-import org.reflections.util.ConfigurationBuilder;
-import org.reflections.util.FilterBuilder;
-
-import static org.reflections.scanners.Scanners.TypesAnnotated;
+import org.diylc.utils.ReflectionUtils;
 
 /**
  * Utility class with component processing methods.
@@ -138,26 +128,7 @@ public class ComponentProcessor {
     } else { // default
     	return null;
     }
-    icon = null;
-    // Draw component icon.
-    try {
-      IDIYComponent<?> componentInstance = (IDIYComponent<?>) clazz.getDeclaredConstructor().newInstance();
-      Image image =
-          new BufferedImage(Presenter.ICON_SIZE, Presenter.ICON_SIZE, java.awt.image.BufferedImage.TYPE_INT_ARGB);
-      Graphics2D g2d = (Graphics2D) image.getGraphics();
-      g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
-      g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
-      g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
-          RenderingHints.VALUE_INTERPOLATION_BICUBIC);
-      g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS,
-          RenderingHints.VALUE_FRACTIONALMETRICS_ON);
-      // g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL,
-      // RenderingHints.VALUE_STROKE_PURE);
-      componentInstance.drawIcon(g2d, Presenter.ICON_SIZE, Presenter.ICON_SIZE);
-      icon = new ImageIcon(image);
-    } catch (Exception e) {
-      LOG.error("Error drawing component icon", e);
-    }
+    icon = new ComponentIcon(clazz);
     ComponentType componentType =
         new ComponentType(name, description, creationMethod, category, namePrefix, author, icon, clazz, zOrder,
             flexibleZOrder, bomPolicy, autoEdit, transformer, keywordPolicy, keywordTag, cacheDrawing, datasheet,
@@ -254,30 +225,24 @@ public class ComponentProcessor {
     if (componentTypes == null) {
       LOG.info("Loading component types.");
       componentTypes = new HashMap<String, List<ComponentType>>();
-      Reflections reflections = new Reflections(
-          new ConfigurationBuilder()
-              .forPackage("org.diylc")
-              .filterInputsBy(new FilterBuilder().includePackage("org.diylc.components"))
-              .setScanners(TypesAnnotated));
-      Set<Class<?>> componentTypeClasses = null;
       try {
-        componentTypeClasses = reflections.getTypesAnnotatedWith(ComponentDescriptor.class, false);
         List<Map<String, Object>> componentSnapshots = LOG_COMPONENT_TYPE_DETAILS ? new ArrayList<>() : null;
 
-        for (Class<?> clazz : componentTypeClasses) {
-          if (!Modifier.isAbstract(clazz.getModifiers()) && IDIYComponent.class.isAssignableFrom(clazz)) {
+        for (Class<?> clazz : ReflectionUtils.getIndexedClasses(IDIYComponent.class)) {
           ComponentType componentType =
               ComponentProcessor.getInstance().extractComponentTypeFrom((Class<? extends IDIYComponent<?>>) clazz);
-            if (componentType == null)
+          if (componentType == null) {
             continue;
+          }
 
           // just to store in the cache
           ComponentProcessor.getInstance().extractProperties(clazz);
 
           // types created only programmatically (e.g. CompositeComponent) don't belong in the
           // palette, but still need to go through extractProperties() above so the cache is warm
-            if (clazz.getAnnotation(ComponentDescriptor.class).hiddenInPalette())
+          if (clazz.getAnnotation(ComponentDescriptor.class).hiddenInPalette()) {
             continue;
+          }
 
           List<ComponentType> nestedList;
           if (componentTypes.containsKey(componentType.getCategory())) {
@@ -314,7 +279,6 @@ public class ComponentProcessor {
             }
           }
         }
-        }
 
         if (LOG_COMPONENT_TYPE_DETAILS && componentSnapshots != null && !componentSnapshots.isEmpty()) {
           try {

diylc/diylc-core/src/main/java/org/diylc/presenter/Presenter.java

@@ -31,7 +31,6 @@ import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.lang.reflect.Modifier;
 import java.util.*;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -3133,16 +3132,8 @@ public class Presenter implements IPlugInPort {
 
   @Override
   public List<INetlistAnalyzer> getNetlistAnalyzers() {
-    Set<Class<?>> classes;
     try {
-      classes = Utils.getClasses("org.diylc.netlist");
-      List<INetlistAnalyzer> result = new ArrayList<INetlistAnalyzer>();
-
-      for (Class<?> clazz : classes) {
-        if (!Modifier.isAbstract(clazz.getModifiers()) && INetlistAnalyzer.class.isAssignableFrom(clazz)) {
-          result.add((INetlistAnalyzer) clazz.getDeclaredConstructor().newInstance());
-        }
-      }
+      List<INetlistAnalyzer> result = ReflectionUtils.getIndexedInstances(INetlistAnalyzer.class);
 
       result.sort(new Comparator<INetlistAnalyzer>() {
 

diylc/diylc-core/src/main/java/org/diylc/serialization/IOldFileParser.java

@@ -26,7 +26,9 @@ import java.util.List;
 import org.w3c.dom.Element;
 
 import org.diylc.core.Project;
+import org.diylc.core.annotations.Indexed;
 
+@Indexed
 public interface IOldFileParser {
 
   boolean canParse(String version);

diylc/diylc-core/src/main/java/org/diylc/serialization/ProjectFileManager.java

@@ -30,7 +30,6 @@ import java.io.InputStreamReader;
 import java.io.OutputStreamWriter;
 import java.io.Reader;
 import java.io.Writer;
-import java.lang.reflect.Modifier;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
@@ -41,7 +40,6 @@ import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 import org.apache.log4j.Logger;
-import org.diylc.appframework.miscutils.Utils;
 import org.diylc.appframework.simplemq.MessageDispatcher;
 import org.diylc.appframework.update.VersionNumber;
 import org.w3c.dom.Document;
@@ -59,6 +57,7 @@ import org.diylc.core.IDIYComponent;
 import org.diylc.core.Project;
 import org.diylc.presenter.Presenter;
 import org.diylc.test.DIYTest;
+import org.diylc.utils.ReflectionUtils;
 
 public class ProjectFileManager {
 
@@ -144,17 +143,10 @@ public class ProjectFileManager {
 
   public List<IOldFileParser> getParsers() {
     if (parsers == null) {
-      parsers = new ArrayList<IOldFileParser>();
-      Set<Class<?>> componentTypeClasses = null;
       try {
-        componentTypeClasses = Utils.getClasses("org.diylc.serialization");
-        for (Class<?> clazz : componentTypeClasses) {
-          if (!Modifier.isAbstract(clazz.getModifiers()) && IOldFileParser.class.isAssignableFrom(clazz)) {
-            IOldFileParser instance = (IOldFileParser) clazz.getDeclaredConstructor().newInstance();
-            parsers.add(instance);
-          }
-        }
+        parsers = ReflectionUtils.getIndexedInstances(IOldFileParser.class);
       } catch (Exception e) {
+        parsers = new ArrayList<IOldFileParser>();
         LOG.error("Could not find old version parsers", e);
       }
     }

diylc/diylc-core/src/main/java/org/diylc/utils/ReflectionUtils.java

@@ -21,23 +21,30 @@
 */
 package org.diylc.utils;
 
-import java.lang.reflect.Modifier;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.Enumeration;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import org.apache.log4j.Logger;
-import org.diylc.appframework.miscutils.Utils;
 
 import org.diylc.core.annotations.IAutoCreator;
+import org.diylc.core.annotations.Indexed;
 import org.diylc.netlist.IGuitarDiagramAnalyzer;
 import org.diylc.netlist.INetlistParser;
-import org.diylc.presenter.Presenter;
 
 public class ReflectionUtils {
   
-  private static final Logger LOG = Logger.getLogger(Presenter.class);
+  private static final Logger LOG = Logger.getLogger(ReflectionUtils.class);
+
+  private static final String SERVICES_DIR = "META-INF/services/";
   
   /**
    * {@link List} of {@link IAutoCreator} objects that are capable of creating more components
@@ -45,19 +52,66 @@ public class ReflectionUtils {
    */ 
   private static List<IAutoCreator> autoCreators;
 
+  /**
+   * Returns the concrete implementations of an {@link Indexed} type, as listed at build time by
+   * {@code diylc-processor}. Classes are loaded but not initialized.
+   */
+  public static <T> List<Class<? extends T>> getIndexedClasses(Class<T> type) {
+    ClassLoader classLoader = ReflectionUtils.class.getClassLoader();
+    // each module jar carries its own index file for the same type
+    Set<String> classNames = new LinkedHashSet<String>();
+    try {
+      Enumeration<URL> indexFiles = classLoader.getResources(SERVICES_DIR + type.getName());
+      while (indexFiles.hasMoreElements()) {
+        try (BufferedReader reader = new BufferedReader(
+            new InputStreamReader(indexFiles.nextElement().openStream(), StandardCharsets.UTF_8))) {
+          String line;
+          while ((line = reader.readLine()) != null) {
+            line = line.trim();
+            if (!line.isEmpty() && !line.startsWith("#")) {
+              classNames.add(line);
+            }
+          }
+        }
+      }
+    } catch (IOException e) {
+      LOG.error("Could not read the class index of " + type.getName(), e);
+    }
+
+    List<Class<? extends T>> result = new ArrayList<Class<? extends T>>(classNames.size());
+    for (String className : classNames) {
+      try {
+        Class<?> clazz = Class.forName(className, false, classLoader);
+        if (type.isAssignableFrom(clazz)) {
+          result.add(clazz.asSubclass(type));
+        } else {
+          LOG.warn("Class index of " + type.getName() + " lists unrelated class " + className);
+        }
+      } catch (ClassNotFoundException e) {
+        LOG.warn("Class index of " + type.getName() + " lists missing class " + className);
+      }
+    }
+    return result;
+  }
+
+  /**
+   * Instantiates every class returned by {@link #getIndexedClasses(Class)} through its no-arg
+   * constructor.
+   */
+  public static <T> List<T> getIndexedInstances(Class<T> type) throws ReflectiveOperationException {
+    List<T> result = new ArrayList<T>();
+    for (Class<? extends T> clazz : getIndexedClasses(type)) {
+      result.add(clazz.getDeclaredConstructor().newInstance());
+    }
+    return result;
+  }
+
   public static List<IAutoCreator> getAutoCreators() {
     if (autoCreators == null) {
-      autoCreators = new ArrayList<IAutoCreator>();
-      Set<Class<?>> classes = null;
       try {
-        classes = Utils.getClasses("org.diylc.components.autocreate");
-        for (Class<?> clazz : classes) {
-          if (IAutoCreator.class.isAssignableFrom(clazz)) {
-            autoCreators.add((IAutoCreator) clazz.getDeclaredConstructor().newInstance());
-            LOG.debug("Loaded auto-creator: " + clazz.getName());
-          }
-        }
+        autoCreators = getIndexedInstances(IAutoCreator.class);
       } catch (Exception e) {
+        autoCreators = new ArrayList<IAutoCreator>();
         LOG.error("Error loading auto-creator types", e);
       }
     }
@@ -65,16 +119,8 @@ public class ReflectionUtils {
   }
   
   public static List<INetlistParser> getNetlistParserDefinitions() {
-    Set<Class<?>> classes;
     try {
-      classes = Utils.getClasses("org.diylc.netlist");
-      List<INetlistParser> result = new ArrayList<INetlistParser>();
-
-      for (Class<?> clazz : classes) {
-        if (!Modifier.isAbstract(clazz.getModifiers()) && INetlistParser.class.isAssignableFrom(clazz)) {
-          result.add((INetlistParser) clazz.getDeclaredConstructor().newInstance());
-        }
-      }
+      List<INetlistParser> result = getIndexedInstances(INetlistParser.class);
 
       Collections.sort(result, new Comparator<INetlistParser>() {
 
@@ -92,16 +138,7 @@ public class ReflectionUtils {
   }
 
   public static IGuitarDiagramAnalyzer getGuitarDiagramAnalyzer() throws Exception {
-    Set<Class<?>> classes;
-    classes = Utils.getClasses("org.diylc.netlist");
-    List<IGuitarDiagramAnalyzer> result = new ArrayList<>();
-
-    for (Class<?> clazz : classes) {
-      if (!Modifier.isAbstract(clazz.getModifiers()) && IGuitarDiagramAnalyzer.class.isAssignableFrom(clazz)) {
-        result.add((IGuitarDiagramAnalyzer) clazz.getDeclaredConstructor().newInstance());
-      }
-    }
-
+    List<IGuitarDiagramAnalyzer> result = getIndexedInstances(IGuitarDiagramAnalyzer.class);
 
     if (result.isEmpty()) {
       return null;

diylc/diylc-core/src/main/resources/update.xml

@@ -611,7 +611,11 @@
 				</org.diylc.appframework.update.Change>
 				<org.diylc.appframework.update.Change>
 					<changeType>IMPROVEMENT</changeType>
-					<description>Improve performance of 'Project Explorer' pane</description>
+					<description>Improved performance of application initialization</description>
+				</org.diylc.appframework.update.Change>
+				<org.diylc.appframework.update.Change>
+					<changeType>IMPROVEMENT</changeType>
+					<description>Improved performance of 'Project Explorer' pane</description>
 				</org.diylc.appframework.update.Change>
 				<org.diylc.appframework.update.Change>
 					<changeType>BUG_FIX</changeType>

diylc/diylc-library/pom.xml

@@ -20,6 +20,10 @@
     
     <dependencies>
         <!-- Internal module dependencies -->
+        <dependency>
+            <groupId>org.diylc</groupId>
+            <artifactId>diylc-processor</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.diylc</groupId>
             <artifactId>diylc-core</artifactId>

diylc/diylc-processor/pom.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.diylc</groupId>
+        <artifactId>diylc-parent</artifactId>
+        <version>6.8.0</version>
+    </parent>
+
+    <artifactId>diylc-processor</artifactId>
+    <name>DIYLC Annotation Processor</name>
+    <description>Build-time indexer that lists the implementations of @Indexed types under META-INF/services</description>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <!-- the processor cannot run while it is itself being compiled -->
+                    <proc>none</proc>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

diylc/diylc-processor/src/main/java/org/diylc/processor/ServiceIndexProcessor.java

@@ -0,0 +1,192 @@
+/*
+
+    DIY Layout Creator (DIYLC).
+    Copyright (c) 2009-2025 held jointly by the individual authors.
+
+    This file is part of DIYLC.
+
+    DIYLC is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    DIYLC is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DIYLC.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+package org.diylc.processor;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.TreeSet;
+
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.AnnotationMirror;
+import javax.lang.model.element.Element;
+import javax.lang.model.element.ElementKind;
+import javax.lang.model.element.Modifier;
+import javax.lang.model.element.TypeElement;
+import javax.lang.model.type.DeclaredType;
+import javax.lang.model.type.TypeKind;
+import javax.lang.model.type.TypeMirror;
+import javax.tools.Diagnostic;
+import javax.tools.FileObject;
+import javax.tools.StandardLocation;
+
+/**
+ * Lists every concrete class of the module being compiled under
+ * {@code META-INF/services/<type>} for each of its supertypes that carries
+ * {@code org.diylc.core.annotations.Indexed}. The application reads these files at startup instead
+ * of scanning the classpath.
+ *
+ * @author Branislav Stojkovic
+ */
+@SupportedAnnotationTypes("*")
+public class ServiceIndexProcessor extends AbstractProcessor {
+
+  private static final String INDEXED_ANNOTATION = "org.diylc.core.annotations.Indexed";
+  private static final String SERVICES_DIR = "META-INF/services/";
+
+  private final Map<String, Set<String>> index = new TreeMap<String, Set<String>>();
+
+  @Override
+  public SourceVersion getSupportedSourceVersion() {
+    return SourceVersion.latestSupported();
+  }
+
+  @Override
+  public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+    if (roundEnv.processingOver()) {
+      writeIndex();
+    } else {
+      for (Element element : roundEnv.getRootElements()) {
+        collect(element);
+      }
+    }
+    return false;
+  }
+
+  private void collect(Element element) {
+    if (!(element instanceof TypeElement)) {
+      return;
+    }
+    TypeElement type = (TypeElement) element;
+    if (isInstantiable(type)) {
+      String className = processingEnv.getElementUtils().getBinaryName(type).toString();
+      for (String service : findIndexedSupertypes(type)) {
+        index.computeIfAbsent(service, k -> new TreeSet<String>()).add(className);
+      }
+    }
+    for (Element enclosed : type.getEnclosedElements()) {
+      if (enclosed.getModifiers().contains(Modifier.STATIC)) {
+        collect(enclosed);
+      }
+    }
+  }
+
+  private boolean isInstantiable(TypeElement type) {
+    return type.getKind() == ElementKind.CLASS && !type.getModifiers().contains(Modifier.ABSTRACT);
+  }
+
+  private Set<String> findIndexedSupertypes(TypeElement type) {
+    Set<String> result = new HashSet<String>();
+    Set<String> visited = new HashSet<String>();
+    Deque<TypeMirror> pending = new ArrayDeque<TypeMirror>();
+    pending.add(type.asType());
+    while (!pending.isEmpty()) {
+      for (TypeMirror supertype : processingEnv.getTypeUtils().directSupertypes(pending.poll())) {
+        if (supertype.getKind() != TypeKind.DECLARED) {
+          continue;
+        }
+        TypeElement supertypeElement = (TypeElement) ((DeclaredType) supertype).asElement();
+        String name = processingEnv.getElementUtils().getBinaryName(supertypeElement).toString();
+        if (!visited.add(name)) {
+          continue;
+        }
+        if (isIndexed(supertypeElement)) {
+          result.add(name);
+        }
+        pending.add(supertype);
+      }
+    }
+    return result;
+  }
+
+  private boolean isIndexed(TypeElement type) {
+    for (AnnotationMirror annotation : type.getAnnotationMirrors()) {
+      TypeElement annotationType = (TypeElement) annotation.getAnnotationType().asElement();
+      if (annotationType.getQualifiedName().contentEquals(INDEXED_ANNOTATION)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  private void writeIndex() {
+    for (Map.Entry<String, Set<String>> entry : index.entrySet()) {
+      String path = SERVICES_DIR + entry.getKey();
+      Set<String> classNames = new TreeSet<String>(entry.getValue());
+      // an incremental build (e.g. in the IDE) compiles only the changed classes, so carry over
+      // the entries from the previous build that still qualify
+      classNames.addAll(readPreviousEntries(path, entry.getKey()));
+      try {
+        FileObject file =
+            processingEnv.getFiler().createResource(StandardLocation.CLASS_OUTPUT, "", path);
+        try (Writer writer =
+            new OutputStreamWriter(file.openOutputStream(), StandardCharsets.UTF_8)) {
+          for (String className : classNames) {
+            writer.write(className);
+            writer.write('\n');
+          }
+        }
+      } catch (IOException e) {
+        processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR,
+            "Could not write " + path + ": " + e.getMessage());
+      }
+    }
+  }
+
+  private Set<String> readPreviousEntries(String path, String service) {
+    Set<String> result = new TreeSet<String>();
+    try {
+      FileObject file =
+          processingEnv.getFiler().getResource(StandardLocation.CLASS_OUTPUT, "", path);
+      try (BufferedReader reader = new BufferedReader(
+          new InputStreamReader(file.openInputStream(), StandardCharsets.UTF_8))) {
+        String line;
+        while ((line = reader.readLine()) != null) {
+          line = line.trim();
+          if (!line.isEmpty() && stillQualifies(line, service)) {
+            result.add(line);
+          }
+        }
+      }
+    } catch (IOException e) {
+      // no previous build output
+    }
+    return result;
+  }
+
+  private boolean stillQualifies(String className, String service) {
+    TypeElement type = processingEnv.getElementUtils().getTypeElement(className.replace('$', '.'));
+    return type != null && isInstantiable(type) && findIndexedSupertypes(type).contains(service);
+  }
+}

diylc/diylc-processor/src/main/resources/META-INF/services/javax.annotation.processing.Processor

@@ -0,0 +1 @@
+org.diylc.processor.ServiceIndexProcessor

diylc/diylc-swing/pom.xml

@@ -20,6 +20,10 @@
     
     <dependencies>
         <!-- Internal module dependencies -->
+        <dependency>
+            <groupId>org.diylc</groupId>
+            <artifactId>diylc-processor</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.diylc</groupId>
             <artifactId>diylc-core</artifactId>

diylc/diylc-swing/src/main/java/org/diylc/swing/plugins/toolbox/ComponentTabbedPane.java

@@ -90,6 +90,8 @@ class ComponentTabbedPane extends JTabbedPane {
   private List<String> blocks;  
 
   private final Map<String, Component> categoryPanels = new HashMap<String, Component>();
+  private final Map<Component, List<ComponentType>> unpopulatedPanels =
+      new HashMap<Component, List<ComponentType>>();
   private boolean refreshing = false;
 
   public ComponentTabbedPane(IPlugInPort plugInPort, ISwingUI swingUI) {
@@ -111,6 +113,7 @@ class ComponentTabbedPane extends JTabbedPane {
     if (lastSelectedTab >= 0 && lastSelectedTab < getTabCount()) {
       setSelectedIndex(lastSelectedTab);
     }
+    populateTab(getSelectedComponent());
 
     addChangeListener(new ChangeListener() {
 
@@ -119,6 +122,7 @@ class ComponentTabbedPane extends JTabbedPane {
         if (refreshing) {
           return;
         }
+        populateTab(getSelectedComponent());
         ConfigurationManager.getInstance().writeValue(LAST_SELECTED_TAB, getSelectedIndex());
         ComponentTabbedPane.this.plugInPort.setNewComponentTypeSlot(null, null, null, false);
         // Refresh recent components if needed
@@ -157,6 +161,11 @@ class ComponentTabbedPane extends JTabbedPane {
         }
         addTab(category, panel);
       }
+      // the tabbed pane takes its height from the tallest tab, so keep one category populated
+      // even while a sparse tab like Favorites is selected
+      if (getTabCount() > 3) {
+        populateTab(getComponentAt(3));
+      }
 
       if (selectedTitle != null) {
         for (int i = 0; i < getTabCount(); i++) {
@@ -175,6 +184,7 @@ class ComponentTabbedPane extends JTabbedPane {
     } else if (getTabCount() > 0) {
       setSelectedIndex(0);
     }
+    populateTab(getSelectedComponent());
   }
 
   @SuppressWarnings("unchecked")
@@ -238,11 +248,21 @@ class ComponentTabbedPane extends JTabbedPane {
     JPanel panel = new JPanel(new BorderLayout());
 
     panel.setOpaque(false);
-    panel.add(createComponentPanel(componentTypes), BorderLayout.CENTER);
+    // buttons are added by populateTab() when the tab is first shown, as creating a button draws
+    // its component icon
+    unpopulatedPanels.put(panel, componentTypes);
 
     return panel;
   }
 
+  private void populateTab(Component panel) {
+    List<ComponentType> componentTypes = unpopulatedPanels.remove(panel);
+    if (componentTypes != null) {
+      ((JPanel) panel).add(createComponentPanel(componentTypes), BorderLayout.CENTER);
+      panel.revalidate();
+    }
+  }
+
   public Container getRecentToolbar() {
     if (recentToolbar == null) {
       recentToolbar = new Container();

diylc/pom.xml

@@ -13,6 +13,7 @@
     <description>A free, open-source, cross-platform tool for drawing circuit layouts</description>
     
     <modules>
+        <module>diylc-processor</module>
         <module>diylc-core</module>
         <module>diylc-library</module>
         <module>diylc-swing</module>
@@ -31,6 +32,13 @@
     <dependencyManagement>
         <dependencies>
             <!-- Internal module dependencies -->
+            <dependency>
+                <groupId>org.diylc</groupId>
+                <artifactId>diylc-processor</artifactId>
+                <version>${project.version}</version>
+                <scope>provided</scope>
+                <optional>true</optional>
+            </dependency>
             <dependency>
                 <groupId>org.diylc</groupId>
                 <artifactId>diylc-core</artifactId>
@@ -94,7 +102,20 @@
                         <source>${maven.compiler.source}</source>
                         <target>${maven.compiler.target}</target>
                         <encoding>${project.build.sourceEncoding}</encoding>
+                        <!-- writes the META-INF/services class index; see org.diylc.core.annotations.Indexed -->
+                        <annotationProcessors>
+                            <annotationProcessor>org.diylc.processor.ServiceIndexProcessor</annotationProcessor>
+                        </annotationProcessors>
                     </configuration>
+                    <executions>
+                        <execution>
+                            <!-- test fixtures must not end up in the index -->
+                            <id>default-testCompile</id>
+                            <configuration>
+                                <proc>none</proc>
+                            </configuration>
+                        </execution>
+                    </executions>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>