Compilers are now plug-in actors.

src/main/kotlin/com/beust/kobalt/api/IAffinity.kt

@@ -0,0 +1,18 @@
+package com.beust.kobalt.api
+
+interface IAffinity {
+    companion object {
+        /**
+         * The recommended default affinity if your plug-in can run this project. Use a higher
+         * number if you expect to compete against other actors and you'd like to win over them.
+         */
+        const val DEFAULT_POSITIVE_AFFINITY = 100
+    }
+
+    /**
+     * @return an integer indicating the affinity of your actor for the given project. The actor that returns
+     * the highest affinity gets selectedyour affinity for running the current project. The runner with
+     * the highest affinity gets selected.
+     */
+    fun affinity(project: Project, context: KobaltContext) : Int
+}

src/main/kotlin/com/beust/kobalt/api/ICompilerContributor.kt

@@ -0,0 +1,16 @@
+package com.beust.kobalt.api
+
+import com.beust.kobalt.TaskResult
+import com.beust.kobalt.maven.dependency.IClasspathDependency
+import java.io.File
+
+interface ICompilerContributor : IAffinity {
+    fun compile(project: Project, context: KobaltContext, info: CompilerActionInfo) : TaskResult
+}
+
+data class CompilerActionInfo(val directory: String?,
+        val dependencies: List<IClasspathDependency>,
+        val sourceFiles: List<String>,
+        val outputDir: File,
+        val compilerArgs: List<String>)
+

src/main/kotlin/com/beust/kobalt/api/ICompilerInterceptor.kt

@@ -1,7 +1,5 @@
 package com.beust.kobalt.api
 
-import com.beust.kobalt.internal.CompilerActionInfo
-
 /**
  * Plug-ins can alter what is passed to the compiler by implementing this interface.
  */

src/main/kotlin/com/beust/kobalt/internal/JUnitRunner.kt

@@ -1,6 +1,6 @@
 package com.beust.kobalt.internal
 
-import com.beust.kobalt.api.IRunnerContributor
+import com.beust.kobalt.api.IAffinity
 import com.beust.kobalt.api.KobaltContext
 import com.beust.kobalt.api.Project
 import com.beust.kobalt.maven.dependency.IClasspathDependency
@@ -10,7 +10,7 @@ public class JUnitRunner() : GenericTestRunner() {
     override val mainClass = "org.junit.runner.JUnitCore"
 
     override fun affinity(project: Project, context: KobaltContext) =
-            if (project.testDependencies.any { it.id.contains("junit")}) IRunnerContributor.DEFAULT_POSITIVE_AFFINITY
+            if (project.testDependencies.any { it.id.contains("junit")}) IAffinity.DEFAULT_POSITIVE_AFFINITY
             else 0
 
     override fun args(project: Project, classpath: List<IClasspathDependency>) = findTestClasses(project, classpath)

src/main/kotlin/com/beust/kobalt/internal/JvmCompiler.kt

@@ -2,10 +2,10 @@ package com.beust.kobalt.internal
 
 import com.beust.kobalt.KobaltException
 import com.beust.kobalt.TaskResult
+import com.beust.kobalt.api.CompilerActionInfo
 import com.beust.kobalt.api.KobaltContext
 import com.beust.kobalt.api.Project
 import com.beust.kobalt.maven.DependencyManager
-import com.beust.kobalt.maven.dependency.IClasspathDependency
 import com.google.inject.Inject
 import java.io.File
 import java.util.*
@@ -51,9 +51,6 @@ class JvmCompiler @Inject constructor(val dependencyManager: DependencyManager)
     }
 }
 
-data class CompilerActionInfo(val directory: String?, val dependencies: List<IClasspathDependency>,
-        val sourceFiles: List<String>, val outputDir: File, val compilerArgs: List<String>)
-
 interface ICompilerAction {
     fun compile(info: CompilerActionInfo): TaskResult
 }

src/main/kotlin/com/beust/kobalt/internal/JvmCompilerPlugin.kt

@@ -1,10 +1,8 @@
 package com.beust.kobalt.internal
 
+import com.beust.kobalt.KobaltException
 import com.beust.kobalt.TaskResult
-import com.beust.kobalt.api.BasePlugin
-import com.beust.kobalt.api.IProjectContributor
-import com.beust.kobalt.api.KobaltContext
-import com.beust.kobalt.api.Project
+import com.beust.kobalt.api.*
 import com.beust.kobalt.api.annotation.ExportedProjectProperty
 import com.beust.kobalt.api.annotation.Task
 import com.beust.kobalt.maven.DepFactory
@@ -138,9 +136,18 @@ abstract class JvmCompilerPlugin @Inject constructor(
     @Task(name = JavaPlugin.TASK_COMPILE, description = "Compile the project")
     fun taskCompile(project: Project) : TaskResult {
         context.variant.maybeGenerateBuildConfig(project, context)
-        return doCompile(project, createCompilerActionInfo(project, context))
+        val info = createCompilerActionInfo(project, context)
+        val compiler = selectAffinityActor(project, context.pluginInfo.compilerContributors)
+        if (compiler != null) {
+            return compiler.compile(project, context, info)
+        } else {
+            throw KobaltException("Couldn't find any compiler for project ${project.name}")
+        }
     }
 
+    private fun <T : IAffinity> selectAffinityActor(project: Project, actors: List<T>) : T? =
+            actors.maxBy { it.affinity(project, context) }
+
     @Task(name = JavaPlugin.TASK_JAVADOC, description = "Run Javadoc")
     fun taskJavadoc(project: Project) = doJavadoc(project, createCompilerActionInfo(project, context))
 

src/main/kotlin/com/beust/kobalt/internal/KobaltPluginXml.kt

@@ -70,6 +70,9 @@ class KobaltPluginXml {
 
     @XmlElement(name = "classpath-interceptors") @JvmField
     var classpathInterceptors: ClassNameXml? = null
+
+    @XmlElement(name = "compiler-contributors") @JvmField
+    var compilerContributors: ClassNameXml? = null
 }
 
 class ContributorXml {
@@ -100,6 +103,7 @@ class PluginInfo(val xml: KobaltPluginXml, val classLoader: ClassLoader?) {
     val runnerContributors = arrayListOf<IRunnerContributor>()
     val testRunnerContributors = arrayListOf<IRunnerContributor>()
     val classpathInterceptors = arrayListOf<IClasspathInterceptor>()
+    val compilerContributors = arrayListOf<ICompilerContributor>()
 
     // Future contributors:
     // source files
@@ -182,6 +186,9 @@ class PluginInfo(val xml: KobaltPluginXml, val classLoader: ClassLoader?) {
         xml.classpathInterceptors?.className?.forEach {
             classpathInterceptors.add(factory.instanceOf(forName(it)) as IClasspathInterceptor)
         }
+        xml.compilerContributors?.className?.forEach {
+            compilerContributors.add(factory.instanceOf(forName(it)) as ICompilerContributor)
+        }
     }
 
     fun addPluginInfo(pluginInfo: PluginInfo) {

src/main/kotlin/com/beust/kobalt/internal/TestNgRunner.kt

@@ -1,6 +1,6 @@
 package com.beust.kobalt.internal
 
-import com.beust.kobalt.api.IRunnerContributor
+import com.beust.kobalt.api.IAffinity
 import com.beust.kobalt.api.KobaltContext
 import com.beust.kobalt.api.Project
 import com.beust.kobalt.maven.dependency.IClasspathDependency
@@ -12,7 +12,7 @@ public class TestNgRunner() : GenericTestRunner() {
     override val mainClass = "org.testng.TestNG"
 
     override fun affinity(project: Project, context: KobaltContext) =
-        if (project.testDependencies.any { it.id.contains("testng")}) IRunnerContributor.DEFAULT_POSITIVE_AFFINITY
+        if (project.testDependencies.any { it.id.contains("testng")}) IAffinity.DEFAULT_POSITIVE_AFFINITY
         else 0
 
     override fun args(project: Project, classpath: List<IClasspathDependency>) = arrayListOf<String>().apply {

src/main/kotlin/com/beust/kobalt/plugin/android/AndroidPlugin.kt

@@ -4,7 +4,6 @@ import com.beust.kobalt.*
 import com.beust.kobalt.api.*
 import com.beust.kobalt.api.annotation.Directive
 import com.beust.kobalt.api.annotation.Task
-import com.beust.kobalt.internal.CompilerActionInfo
 import com.beust.kobalt.maven.MavenId
 import com.beust.kobalt.maven.dependency.FileDependency
 import com.beust.kobalt.maven.dependency.IClasspathDependency
@@ -129,7 +128,6 @@ public class AndroidPlugin @Inject constructor(val javaCompiler: JavaCompiler, v
         val androidJar = Paths.get(androidHome(project), "platforms", "android-$compileSdkVersion", "android.jar")
         val applicationId = configurationFor(project)?.applicationId!!
         val intermediates = AndroidFiles.intermediates(project)
-        val crunchedPngDir = KFiles.joinAndMakeDir(AndroidFiles.intermediates(project).toString(), "res")
 
 //        AaptCommand(project, aapt, "crunch").call(listOf(
 //                "-v",
@@ -392,7 +390,7 @@ public class AndroidPlugin @Inject constructor(val javaCompiler: JavaCompiler, v
     // IRunContributor
     override fun affinity(project: Project, context: KobaltContext): Int {
         val manifest = AndroidFiles.manifest(project, context)
-        return if (File(manifest).exists()) IRunnerContributor.DEFAULT_POSITIVE_AFFINITY else 0
+        return if (File(manifest).exists()) IAffinity.DEFAULT_POSITIVE_AFFINITY else 0
     }
 
     override fun run(project: Project, context: KobaltContext, classpath: List<IClasspathDependency>): TaskResult {

src/main/kotlin/com/beust/kobalt/plugin/application/ApplicationPlugin.kt

@@ -74,7 +74,7 @@ class ApplicationPlugin @Inject constructor(val executors: KobaltExecutors,
     // IRunContributor
 
     override fun affinity(project: Project, context: KobaltContext): Int {
-        return if (configurationFor(project) != null) IRunnerContributor.DEFAULT_POSITIVE_AFFINITY else 0
+        return if (configurationFor(project) != null) IAffinity.DEFAULT_POSITIVE_AFFINITY else 0
     }
 
     override fun run(project: Project, context: KobaltContext, classpath: List<IClasspathDependency>): TaskResult {

src/main/kotlin/com/beust/kobalt/plugin/java/JavaCompiler.kt

@@ -3,9 +3,9 @@ package com.beust.kobalt.plugin.java
 import com.beust.kobalt.JavaInfo
 import com.beust.kobalt.SystemProperties
 import com.beust.kobalt.TaskResult
+import com.beust.kobalt.api.CompilerActionInfo
 import com.beust.kobalt.api.KobaltContext
 import com.beust.kobalt.api.Project
-import com.beust.kobalt.internal.CompilerActionInfo
 import com.beust.kobalt.internal.ICompilerAction
 import com.beust.kobalt.internal.JvmCompiler
 import com.beust.kobalt.misc.KFiles

src/main/kotlin/com/beust/kobalt/plugin/java/JavaPlugin.kt

@@ -1,12 +1,9 @@
 package com.beust.kobalt.plugin.java
 
 import com.beust.kobalt.TaskResult
-import com.beust.kobalt.api.BasePlugin
-import com.beust.kobalt.api.Kobalt
-import com.beust.kobalt.api.Project
+import com.beust.kobalt.api.*
 import com.beust.kobalt.api.annotation.Directive
 import com.beust.kobalt.api.annotation.Task
-import com.beust.kobalt.internal.CompilerActionInfo
 import com.beust.kobalt.internal.JvmCompiler
 import com.beust.kobalt.internal.JvmCompilerPlugin
 import com.beust.kobalt.maven.DepFactory
@@ -30,7 +27,8 @@ class JavaPlugin @Inject constructor(
         override val executors: KobaltExecutors,
         val javaCompiler: JavaCompiler,
         override val jvmCompiler: JvmCompiler)
-        : JvmCompilerPlugin(localRepo, files, depFactory, dependencyManager, executors, jvmCompiler) {
+        : JvmCompilerPlugin(localRepo, files, depFactory, dependencyManager, executors, jvmCompiler),
+            ICompilerContributor {
     companion object {
         const val PLUGIN_NAME = "Java"
         const val TASK_COMPILE = "compile"
@@ -91,6 +89,13 @@ class JavaPlugin @Inject constructor(
             }
         return result
     }
+
+    // ICompilerContributor
+
+    override fun affinity(project: Project, context: KobaltContext) =
+        if (project.sourceSuffix == ".java") 1 else 0
+
+    override fun compile(project: Project, context: KobaltContext, info: CompilerActionInfo) = doCompile(project, info)
 }
 
 @Directive

src/main/kotlin/com/beust/kobalt/plugin/kotlin/KotlinCompiler.kt

@@ -1,10 +1,10 @@
 package com.beust.kobalt.plugin.kotlin;
 
 import com.beust.kobalt.TaskResult
+import com.beust.kobalt.api.CompilerActionInfo
 import com.beust.kobalt.api.Kobalt
 import com.beust.kobalt.api.KobaltContext
 import com.beust.kobalt.api.Project
-import com.beust.kobalt.internal.CompilerActionInfo
 import com.beust.kobalt.internal.ICompilerAction
 import com.beust.kobalt.internal.JvmCompiler
 import com.beust.kobalt.maven.DepFactory

src/main/kotlin/com/beust/kobalt/plugin/kotlin/KotlinPlugin.kt

@@ -1,16 +1,14 @@
 package com.beust.kobalt.plugin.kotlin
 
 import com.beust.kobalt.TaskResult
-import com.beust.kobalt.api.BasePlugin
-import com.beust.kobalt.api.IClasspathContributor
-import com.beust.kobalt.api.Kobalt
-import com.beust.kobalt.api.Project
+import com.beust.kobalt.api.*
 import com.beust.kobalt.api.annotation.Directive
 import com.beust.kobalt.api.annotation.Task
-import com.beust.kobalt.internal.CompilerActionInfo
 import com.beust.kobalt.internal.JvmCompiler
 import com.beust.kobalt.internal.JvmCompilerPlugin
-import com.beust.kobalt.maven.*
+import com.beust.kobalt.maven.DepFactory
+import com.beust.kobalt.maven.DependencyManager
+import com.beust.kobalt.maven.LocalRepo
 import com.beust.kobalt.maven.dependency.FileDependency
 import com.beust.kobalt.maven.dependency.IClasspathDependency
 import com.beust.kobalt.maven.dependency.MavenDependency
@@ -30,7 +28,7 @@ class KotlinPlugin @Inject constructor(
         override val executors: KobaltExecutors,
         override val jvmCompiler: JvmCompiler)
         : JvmCompilerPlugin(localRepo, files, depFactory, dependencyManager, executors, jvmCompiler),
-            IClasspathContributor {
+            IClasspathContributor, ICompilerContributor {
 
     companion object {
         const val PLUGIN_NAME = "Kotlin"
@@ -111,6 +109,13 @@ class KotlinPlugin @Inject constructor(
         } else {
             listOf()
         }
+
+    // ICompilerContributor
+
+    override fun affinity(project: Project, context: KobaltContext) =
+            if (project.sourceSuffix == ".kt") 1 else 0
+
+    override fun compile(project: Project, context: KobaltContext, info: CompilerActionInfo) = doCompile(project, info)
 }
 
 /**

src/main/resources/META-INF/kobalt-plugin.xml

@@ -48,4 +48,8 @@
     <classpath-interceptors>
         <class-name>com.beust.kobalt.plugin.android.AndroidPlugin</class-name>
     </classpath-interceptors>
+    <compiler-contributors>
+        <class-name>com.beust.kobalt.plugin.java.JavaPlugin</class-name>
+        <class-name>com.beust.kobalt.plugin.kotlin.KotlinPlugin</class-name>
+    </compiler-contributors>
 </kobalt-plugin>