use annotations processor to create extensions

build.gradle

@@ -47,6 +47,9 @@ dependencies {
 
     def room_version = "2.5.0"
 
+    implementation project(':libs:annotation')
+    annotationProcessor project(':libs:annotation-processor')
+
     coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.1.8'
 
     implementation "androidx.room:room-runtime:$room_version"

libs/annotation-processor/build.gradle

@@ -0,0 +1,21 @@
+plugins {
+    id 'java-library'
+}
+
+repositories {
+    google()
+    mavenCentral()
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+dependencies {
+
+    implementation project(':libs:annotation')
+
+    annotationProcessor 'com.google.auto.service:auto-service:1.0-rc5'
+    compileOnly 'com.google.auto.service:auto-service:1.0-rc5'
+
+}

libs/annotation-processor/src/main/java/im/conversations/android/annotation/processor/XmlElementProcessor.java

@@ -0,0 +1,144 @@
+package im.conversations.android.annotation.processor;
+
+import com.google.auto.service.AutoService;
+import com.google.common.base.Objects;
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableMap;
+import im.conversations.android.annotation.XmlElement;
+import im.conversations.android.annotation.XmlPackage;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.Processor;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.annotation.processing.SupportedSourceVersion;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.Element;
+import javax.lang.model.element.PackageElement;
+import javax.lang.model.element.TypeElement;
+import javax.tools.JavaFileObject;
+
+@AutoService(Processor.class)
+@SupportedSourceVersion(SourceVersion.RELEASE_11)
+@SupportedAnnotationTypes("im.conversations.android.annotation.XmlElement")
+public class XmlElementProcessor extends AbstractProcessor {
+
+    @Override
+    public boolean process(Set<? extends TypeElement> set, RoundEnvironment roundEnvironment) {
+        final Set<? extends Element> elements =
+                roundEnvironment.getElementsAnnotatedWith(XmlElement.class);
+        final ImmutableMap.Builder<Id, String> builder = ImmutableMap.<Id, String>builder();
+        for (final Element element : elements) {
+            if (element instanceof TypeElement) {
+                final TypeElement typeElement = (TypeElement) element;
+                final Id id = of(typeElement);
+                builder.put(id, typeElement.getQualifiedName().toString());
+            }
+        }
+        final ImmutableMap<Id, String> maps = builder.build();
+        if (maps.isEmpty()) {
+            return false;
+        }
+        final JavaFileObject extensionFile;
+        try {
+            extensionFile =
+                    processingEnv
+                            .getFiler()
+                            .createSourceFile("im.conversations.android.xmpp.Extensions");
+        } catch (final IOException e) {
+            throw new RuntimeException(e);
+        }
+        try (final PrintWriter out = new PrintWriter(extensionFile.openWriter())) {
+            out.println("package im.conversations.android.xmpp;");
+            out.println("import com.google.common.collect.BiMap;");
+            out.println("import com.google.common.collect.ImmutableBiMap;");
+            out.println("import im.conversations.android.xmpp.ExtensionFactory;");
+            out.println("import im.conversations.android.xmpp.model.Extension;");
+            out.print("\n");
+            out.println("public final class Extensions {");
+            out.println(
+                    "public static final BiMap<ExtensionFactory.Id, Class<? extends Extension>>"
+                            + " EXTENSION_CLASS_MAP;");
+            out.println("static {");
+            out.println(
+                    "final var builder = new ImmutableBiMap.Builder<ExtensionFactory.Id, Class<?"
+                            + " extends Extension>>();");
+            for (final Map.Entry<Id, String> entry : maps.entrySet()) {
+                Id id = entry.getKey();
+                String clazz = entry.getValue();
+                out.format(
+                        "builder.put(new ExtensionFactory.Id(\"%s\",\"%s\"),%s.class);",
+                        id.name, id.namespace, clazz);
+                out.print("\n");
+            }
+            out.println("EXTENSION_CLASS_MAP = builder.build();");
+            out.println("}");
+            out.println(" private Extensions() {}");
+            out.println("}");
+            // writing generated file to out …
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+        return true;
+    }
+
+    private static Id of(final TypeElement typeElement) {
+        final XmlElement xmlElement = typeElement.getAnnotation(XmlElement.class);
+        PackageElement packageElement = (PackageElement) typeElement.getEnclosingElement();
+        XmlPackage xmlPackage = packageElement.getAnnotation(XmlPackage.class);
+        if (xmlElement == null) {
+            throw new IllegalStateException(
+                    String.format(
+                            "%s is not annotated as @XmlElement",
+                            typeElement.getQualifiedName().toString()));
+        }
+        final String packageNamespace = xmlPackage == null ? null : xmlPackage.namespace();
+        final String elementName = xmlElement.name();
+        final String elementNamespace = xmlElement.namespace();
+        final String namespace;
+        if (!Strings.isNullOrEmpty(elementNamespace)) {
+            namespace = elementNamespace;
+        } else if (!Strings.isNullOrEmpty(packageNamespace)) {
+            namespace = packageNamespace;
+        } else {
+            throw new IllegalStateException(
+                    String.format(
+                            "%s does not declare a namespace",
+                            typeElement.getQualifiedName().toString()));
+        }
+        final String name;
+        if (Strings.isNullOrEmpty(elementName)) {
+            name = typeElement.getSimpleName().toString().toLowerCase(Locale.ROOT);
+        } else {
+            name = elementName;
+        }
+        return new Id(name, namespace);
+    }
+
+    public static class Id {
+        public final String name;
+        public final String namespace;
+
+        public Id(String name, String namespace) {
+            this.name = name;
+            this.namespace = namespace;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            Id id = (Id) o;
+            return Objects.equal(name, id.name) && Objects.equal(namespace, id.namespace);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hashCode(name, namespace);
+        }
+    }
+}

libs/annotation/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+    id 'java-library'
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_7
+    targetCompatibility = JavaVersion.VERSION_1_7
+}

libs/annotation/src/main/java/im/conversations/android/annotation/XmlElement.java

@@ -5,7 +5,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Retention(RetentionPolicy.RUNTIME)
+@Retention(RetentionPolicy.SOURCE)
 @Target({ElementType.TYPE})
 public @interface XmlElement {
 

libs/annotation/src/main/java/im/conversations/android/annotation/XmlPackage.java

@@ -5,7 +5,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Retention(RetentionPolicy.RUNTIME)
+@Retention(RetentionPolicy.SOURCE)
 @Target(ElementType.PACKAGE)
 public @interface XmlPackage {
     String namespace();

settings.gradle

@@ -1 +1,3 @@
+include ':libs:annotation'
+include ':libs:annotation-processor'
 rootProject.name = 'Conversations'

src/main/java/eu/siacs/conversations/xml/XmlReader.java

@@ -3,7 +3,7 @@ package eu.siacs.conversations.xml;
 import android.util.Log;
 import android.util.Xml;
 import eu.siacs.conversations.Config;
-import im.conversations.android.xmpp.Extensions;
+import im.conversations.android.xmpp.ExtensionFactory;
 import im.conversations.android.xmpp.model.Extension;
 import java.io.Closeable;
 import java.io.IOException;
@@ -106,7 +106,7 @@ public class XmlReader implements Closeable {
         final var attributes = currentTag.getAttributes();
         final var namespace = attributes.get("xmlns");
         final var name = currentTag.getName();
-        final Element element = Extensions.create(name, namespace);
+        final Element element = ExtensionFactory.create(name, namespace);
         element.setAttributes(currentTag.getAttributes());
         Tag nextTag = this.readTag();
         if (nextTag == null) {

src/main/java/im/conversations/android/database/CredentialStore.java

@@ -201,7 +201,8 @@ public class CredentialStore {
         return getEncryptedFile(getCredentialStoreFile());
     }
 
-    private EncryptedFile getEncryptedFile(final File file) throws GeneralSecurityException, IOException {
+    private EncryptedFile getEncryptedFile(final File file)
+            throws GeneralSecurityException, IOException {
         final KeyGenParameterSpec keyGenParameterSpec = MasterKeys.AES256_GCM_SPEC;
         final String mainKeyAlias = MasterKeys.getOrCreate(keyGenParameterSpec);
         return new EncryptedFile.Builder(

src/main/java/im/conversations/android/xmpp/ExtensionFactory.java

@@ -0,0 +1,65 @@
+package im.conversations.android.xmpp;
+
+import com.google.common.base.Objects;
+import eu.siacs.conversations.xml.Element;
+import im.conversations.android.xmpp.model.Extension;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+
+public final class ExtensionFactory {
+
+    public static Element create(final String name, final String namespace) {
+        final Class<? extends Element> clazz = of(name, namespace);
+        if (clazz == null) {
+            return new Element(name, namespace);
+        }
+        final Constructor<? extends Element> constructor;
+        try {
+            constructor = clazz.getDeclaredConstructor();
+        } catch (final NoSuchMethodException e) {
+            throw new IllegalStateException(
+                    String.format("%s has no default constructor", clazz.getName()));
+        }
+        try {
+            return constructor.newInstance();
+        } catch (final IllegalAccessException
+                | InstantiationException
+                | InvocationTargetException e) {
+            throw new IllegalStateException(
+                    String.format("%s has inaccessible default constructor", clazz.getName()));
+        }
+    }
+
+    private static Class<? extends Element> of(final String name, final String namespace) {
+        return Extensions.EXTENSION_CLASS_MAP.get(new Id(name, namespace));
+    }
+
+    public static Id id(final Class<? extends Extension> clazz) {
+        return Extensions.EXTENSION_CLASS_MAP.inverse().get(clazz);
+    }
+
+    private ExtensionFactory() {}
+
+    public static class Id {
+        public final String name;
+        public final String namespace;
+
+        public Id(String name, String namespace) {
+            this.name = name;
+            this.namespace = namespace;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            Id id = (Id) o;
+            return Objects.equal(name, id.name) && Objects.equal(namespace, id.namespace);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hashCode(name, namespace);
+        }
+    }
+}

src/main/java/im/conversations/android/xmpp/Extensions.java

@@ -1,135 +0,0 @@
-package im.conversations.android.xmpp;
-
-import com.google.common.base.Objects;
-import com.google.common.base.Strings;
-import com.google.common.collect.BiMap;
-import com.google.common.collect.ImmutableBiMap;
-import eu.siacs.conversations.xml.Element;
-import im.conversations.android.annotation.XmlElement;
-import im.conversations.android.annotation.XmlPackage;
-import im.conversations.android.xmpp.model.Extension;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.InvocationTargetException;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Locale;
-
-public final class Extensions {
-
-    // TODO these two maps can easily be generated by an annotation processor
-    private static final List<Class<? extends Extension>> ELEMENTS =
-            Arrays.asList(
-                    im.conversations.android.xmpp.model.blocking.Item.class,
-                    im.conversations.android.xmpp.model.blocking.Block.class,
-                    im.conversations.android.xmpp.model.blocking.Blocklist.class,
-                    im.conversations.android.xmpp.model.blocking.Unblock.class,
-                    im.conversations.android.xmpp.model.capabilties.LegacyCapabilities.class,
-                    im.conversations.android.xmpp.model.capabilties.Capabilities.class,
-                    im.conversations.android.xmpp.model.data.Data.class,
-                    im.conversations.android.xmpp.model.data.Field.class,
-                    im.conversations.android.xmpp.model.data.Value.class,
-                    im.conversations.android.xmpp.model.disco.info.Feature.class,
-                    im.conversations.android.xmpp.model.disco.info.Identity.class,
-                    im.conversations.android.xmpp.model.disco.info.InfoQuery.class,
-                    im.conversations.android.xmpp.model.disco.items.Item.class,
-                    im.conversations.android.xmpp.model.disco.items.ItemsQuery.class,
-                    im.conversations.android.xmpp.model.roster.Query.class,
-                    im.conversations.android.xmpp.model.roster.Item.class,
-                    im.conversations.android.xmpp.model.streams.Features.class,
-                    im.conversations.android.xmpp.model.Hash.class);
-
-    private static final BiMap<Id, Class<? extends Extension>> EXTENSION_CLASS_MAP;
-
-    static {
-        final var builder = new ImmutableBiMap.Builder<Id, Class<? extends Extension>>();
-        for (final Class<? extends Extension> clazz : ELEMENTS) {
-            builder.put(of(clazz), clazz);
-        }
-        EXTENSION_CLASS_MAP = builder.build();
-    }
-
-    private static Id of(final Class<? extends Extension> clazz) {
-        final XmlElement xmlElement = clazz.getAnnotation(XmlElement.class);
-        final Package clazzPackage = clazz.getPackage();
-        final XmlPackage xmlPackage =
-                clazzPackage == null ? null : clazzPackage.getAnnotation(XmlPackage.class);
-        if (xmlElement == null) {
-            throw new IllegalStateException(
-                    String.format("%s is not annotated as @XmlElement", clazz.getName()));
-        }
-        final String packageNamespace = xmlPackage == null ? null : xmlPackage.namespace();
-        final String elementName = xmlElement.name();
-        final String elementNamespace = xmlElement.namespace();
-        final String namespace;
-        if (!Strings.isNullOrEmpty(elementNamespace)) {
-            namespace = elementNamespace;
-        } else if (!Strings.isNullOrEmpty(packageNamespace)) {
-            namespace = packageNamespace;
-        } else {
-            throw new IllegalStateException(
-                    String.format("%s does not declare a namespace", clazz.getName()));
-        }
-        final String name;
-        if (Strings.isNullOrEmpty(elementName)) {
-            name = clazz.getSimpleName().toLowerCase(Locale.ROOT);
-        } else {
-            name = elementName;
-        }
-        return new Id(name, namespace);
-    }
-
-    public static Element create(final String name, final String namespace) {
-        final Class<? extends Element> clazz = of(name, namespace);
-        if (clazz == null) {
-            return new Element(name, namespace);
-        }
-        final Constructor<? extends Element> constructor;
-        try {
-            constructor = clazz.getDeclaredConstructor();
-        } catch (final NoSuchMethodException e) {
-            throw new IllegalStateException(
-                    String.format("%s has no default constructor", clazz.getName()));
-        }
-        try {
-            return constructor.newInstance();
-        } catch (final IllegalAccessException
-                | InstantiationException
-                | InvocationTargetException e) {
-            throw new IllegalStateException(
-                    String.format("%s has inaccessible default constructor", clazz.getName()));
-        }
-    }
-
-    private static Class<? extends Element> of(final String name, final String namespace) {
-        return EXTENSION_CLASS_MAP.get(new Id(name, namespace));
-    }
-
-    public static Id id(final Class<? extends Extension> clazz) {
-        return EXTENSION_CLASS_MAP.inverse().get(clazz);
-    }
-
-    private Extensions() {}
-
-    public static class Id {
-        public final String name;
-        public final String namespace;
-
-        public Id(String name, String namespace) {
-            this.name = name;
-            this.namespace = namespace;
-        }
-
-        @Override
-        public boolean equals(Object o) {
-            if (this == o) return true;
-            if (o == null || getClass() != o.getClass()) return false;
-            Id id = (Id) o;
-            return Objects.equal(name, id.name) && Objects.equal(namespace, id.namespace);
-        }
-
-        @Override
-        public int hashCode() {
-            return Objects.hashCode(name, namespace);
-        }
-    }
-}

src/main/java/im/conversations/android/xmpp/model/Extension.java

@@ -1,15 +1,15 @@
 package im.conversations.android.xmpp.model;
 
 import eu.siacs.conversations.xml.Element;
-import im.conversations.android.xmpp.Extensions;
+import im.conversations.android.xmpp.ExtensionFactory;
 
 public class Extension extends Element {
 
-    private Extension(final Extensions.Id id) {
+    private Extension(final ExtensionFactory.Id id) {
         super(id.name, id.namespace);
     }
 
     public Extension(final Class<? extends Extension> clazz) {
-        this(Extensions.id(clazz));
+        this(ExtensionFactory.id(clazz));
     }
 }