kapt: Support Kotlin code generation

libraries/examples/annotation-processor-example/src/main/kotlin/example/ExampleAnnotationProcessor.kt

@@ -1,5 +1,6 @@
 package example
 
+import java.io.File
 import javax.annotation.processing.AbstractProcessor
 import javax.annotation.processing.RoundEnvironment
 import javax.lang.model.SourceVersion
@@ -12,6 +13,8 @@ public class ExampleAnnotationProcessor : AbstractProcessor() {
     private companion object {
         val ANNOTATION_FQ_NAME = javaClass<ExampleAnnotation>().getCanonicalName()
         val SUFFIX_OPTION = "suffix"
+        val GENERATE_KOTLIN_CODE_OPTION = "generate.kotlin.code"
+        val KAPT_KOTLIN_GENERATED_OPTION = "kapt.kotlin.generated"
     }
 
     override fun process(annotations: MutableSet<out TypeElement>?, roundEnv: RoundEnvironment): Boolean {
@@ -20,17 +23,27 @@ public class ExampleAnnotationProcessor : AbstractProcessor() {
         val elementUtils = processingEnv.getElementUtils()
         val filer = processingEnv.getFiler()
 
-        val generatedFileSuffix = processingEnv.getOptions().get(SUFFIX_OPTION) ?: "Generated"
+        val options = processingEnv.getOptions()
+        val generatedFileSuffix = options[SUFFIX_OPTION] ?: "Generated"
+        val generateKotlinCode = "true" == options[GENERATE_KOTLIN_CODE_OPTION]
+        val kotlinGenerated = options[KAPT_KOTLIN_GENERATED_OPTION]
 
         for (element in elements) {
             val packageName = elementUtils.getPackageOf(element).getQualifiedName().toString()
-            val className = element.getSimpleName().toString().capitalize() + generatedFileSuffix
+            val simpleName = element.getSimpleName()
+            val className = simpleName.toString().capitalize() + generatedFileSuffix
 
             filer.createSourceFile(className).openWriter().use { with(it) {
                 appendln("package $packageName;")
-                appendln()
                 appendln("public final class $className {}")
             }}
+
+            if (generateKotlinCode && kotlinGenerated != null && element.getKind() == ElementKind.CLASS) {
+                File(kotlinGenerated, "$simpleName.kt").writer().buffered().use {
+                    it.appendln("package $packageName")
+                    it.appendln("fun $simpleName.customToString() = \"$simpleName: \" + toString()")
+                }
+            }
         }
 
         return true;

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/AnnotationProcessingManager.kt

@@ -54,6 +54,12 @@ public class AnnotationProcessingManager(
         return File(aptWorkingDir, "$WRAPPERS_DIRECTORY/annotations.$taskQualifier.txt")
     }
 
+    fun getGeneratedKotlinSourceDir(): File {
+        val kotlinGeneratedDir = File(aptWorkingDir, "kotlinGenerated")
+        if (!kotlinGeneratedDir.exists()) kotlinGeneratedDir.mkdirs()
+        return kotlinGeneratedDir
+    }
+
     fun setupKapt() {
         if (aptFiles.isEmpty()) return
 
@@ -72,7 +78,8 @@ public class AnnotationProcessingManager(
 
         addGeneratedSourcesOutputToCompilerArgs(javaTask, aptOutputDir)
 
-        appendAnnotationsFileLocationArgument()
+
+        appendAnnotationsArguments()
         appendAdditionalComplerArgs()
     }
 
@@ -102,9 +109,10 @@ public class AnnotationProcessingManager(
         }
     }
 
-    private fun appendAnnotationsFileLocationArgument() {
+    private fun appendAnnotationsArguments() {
         javaTask.modifyCompilerArguments { list ->
             list.add("-Akapt.annotations=" + getAnnotationFile())
+            list.add("-Akapt.kotlin.generated=" + getGeneratedKotlinSourceDir())
         }
     }
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KotlinPlugin.kt

@@ -609,11 +609,13 @@ private fun Project.initKapt(
 
     kotlinTask.doFirst {
         kaptManager.generateJavaHackFile()
+        kotlinAfterJavaTask?.source(kaptManager.getGeneratedKotlinSourceDir())
     }
 
     javaTask.doFirst {
         kaptManager.setupKapt()
         kaptManager.generateJavaHackFile()
+        kotlinAfterJavaTask?.source(kaptManager.getGeneratedKotlinSourceDir())
     }
 
     javaTask.doLast {

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/KotlinGradlePluginIT.kt

@@ -158,4 +158,19 @@ class KotlinGradleIT: BaseGradleIT() {
             assertFileExists("build/classes/main/example/AncestorClassGenerated.class")
         }
     }
+
+    Test fun testKaptOutputKotlinCode() {
+        Project("kaptOutputKotlinCode", "1.12").build("build") {
+            assertSuccessful()
+            assertContains("kapt: Using class file stubs")
+            assertContains(":compileKotlin")
+            assertContains(":compileJava")
+            assertFileExists("build/tmp/kapt/main/wrappers/annotations.main.txt")
+            assertFileExists("build/generated/source/kapt/main/TestClassCustomized.java")
+            assertFileExists("build/tmp/kapt/main/kotlinGenerated/TestClass.kt")
+            assertFileExists("build/classes/main/example/TestClass.class")
+            assertFileExists("build/classes/main/example/TestClassCustomized.class")
+        }
+    }
+
 }

libraries/tools/kotlin-gradle-plugin/src/test/resources/testProject/kaptOutputKotlinCode/build.gradle

@@ -0,0 +1,43 @@
+buildscript {
+    repositories {
+        mavenCentral()
+        maven {
+            url 'file://' + pathToKotlinPlugin
+        }
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:0.1-SNAPSHOT"
+    }
+}
+
+apply plugin: "java"
+apply plugin: "kotlin"
+
+repositories {
+    maven {
+        url 'file://' + pathToKotlinPlugin
+    }
+    mavenCentral()
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:0.1-SNAPSHOT"
+    compile "org.jetbrains.kotlin:annotation-processor-example:0.1-SNAPSHOT"
+    kapt "org.jetbrains.kotlin:annotation-processor-example:0.1-SNAPSHOT"
+}
+
+task show << {
+    buildscript.configurations.classpath.each { println it }
+}
+
+task wrapper(type: Wrapper) {
+    gradleVersion="1.12"
+}
+
+kapt {
+    generateStubs = true
+    arguments {
+        arg("suffix", "Customized")
+        arg("generate.kotlin.code", "true")
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/test/resources/testProject/kaptOutputKotlinCode/src/main/java/test.kt

@@ -0,0 +1,10 @@
+package example
+
+@example.ExampleAnnotation
+public class TestClass {
+
+    fun test() {
+        println(this.customToString())
+    }
+
+}