load a class from source code string

loadclass.kt

import org.jetbrains.kotlin.cli.common.arguments.K2JVMCompilerArguments
import org.jetbrains.kotlin.cli.common.messages.MessageRenderer
import org.jetbrains.kotlin.cli.common.messages.PrintingMessageCollector
import org.jetbrains.kotlin.cli.jvm.K2JVMCompiler
import org.jetbrains.kotlin.config.Services
import java.io.File
import java.io.FileNotFoundException
import java.io.IOException
import java.io.PrintWriter
import java.net.URLClassLoader
import java.nio.file.Files
import java.util.concurrent.ThreadLocalRandom
import kotlin.reflect.full.createInstance

/*
pom changes:
<kotlin.version>1.3.0-rc-190</kotlin.version>

   <repository>
      <id>kotlin-eap</id>
      <url>http://dl.bintray.com/kotlin/kotlin-eap/</url>
    </repository>
    <repository>
      <id>kotlin-dev</id>
      <url>http://dl.bintray.com/kotlin/kotlin-dev/</url>
    </repository>
    
      <dependency>
        <groupId>org.jetbrains.kotlin</groupId>
        <artifactId>kotlin-script-util</artifactId>
        <version>${kotlin.version}</version>
      </dependency>
      <dependency>
        <groupId>org.jetbrains.kotlin</groupId>
        <artifactId>kotlin-compiler-embeddable</artifactId>
        <version>${kotlin.version}</version>
      </dependency>
      <dependency>
        <groupId>org.jetbrains.kotlin</groupId>
        <artifactId>kotlin-script-runtime</artifactId>
        <version>${kotlin.version}</version>
      </dependency>
      <dependency>
        <groupId>org.jetbrains.kotlin</groupId>
        <artifactId>kotlin-scripting-jvm-host</artifactId>
        <version>${kotlin.version}</version>
      </dependency>
      <dependency>
        <groupId>org.jetbrains.kotlin</groupId>
        <artifactId>kotlin-compiler</artifactId>
        <version>${kotlin.version}</version>
      </dependency>
*/
inline fun <reified T> createAndLoad(className: String, classString: String): T {
  val random = ThreadLocalRandom.current()
  val dir: File = Files.createTempDirectory(System.currentTimeMillis().toString()+ "_" + random.nextInt()).toFile()
  try {
    val codegenOutputFile = File(dir.absolutePath + "/source.kt")
    val writer = PrintWriter(codegenOutputFile, "UTF-8")
    writer.println(classString)
    writer.close()
    val compileOutputDir = dir
    println(JvmCompile.exe(codegenOutputFile, compileOutputDir)) //should be true

    return Initializer(compileOutputDir)
        .createInstance<T>(className)!!
//                ?.accept("Hello, world!")
  } finally {
    delete(dir)
  }
}

@Throws(IOException::class)
fun delete(f: File) {
  if (f.isDirectory()) {
    for (c in f.listFiles())
      delete(c)
  }
  if (!f.delete())
    throw FileNotFoundException("Failed to delete file: $f")
}

object JvmCompile {

  fun exe(input: File, output: File): Boolean = K2JVMCompiler().run {
    val args = K2JVMCompilerArguments().apply {
      freeArgs = listOf(input.absolutePath)
      loadBuiltInsFromDependencies = true
      destination = output.absolutePath
      classpath =
          System.getProperty("java.class.path")
              .split(System.getProperty("path.separator"))
              .filter {
                File(it).exists() && File(it).canRead()
              }.joinToString(":")
      noStdlib = true
      noReflect = true
      skipRuntimeVersionCheck = true
      reportPerf = true
    }
    output.deleteOnExit()
    execImpl(
        PrintingMessageCollector(
            System.out,
            MessageRenderer.WITHOUT_PATHS, true),
        Services.EMPTY,
        args)
  }.code == 0

}


class Initializer(private val root: File) {

  val loader = URLClassLoader(
      listOf(root.toURI().toURL()).toTypedArray(),
      this::class.java.classLoader)

  @Suppress("UNCHECKED_CAST")
  inline fun <reified T> loadCompiledObject(clazzName: String): T? = loader.loadClass(clazzName).kotlin.objectInstance as T

  @Suppress("UNCHECKED_CAST")
  inline fun <reified T> createInstance(clazzName: String): T? = loader.loadClass(clazzName).kotlin.createInstance() as T

}