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/* NSC -- new Scala compiler
* Copyright 2005-2007 LAMP/EPFL
* @author Lex Spoon
*/
// $Id$
package scala.tools.nsc
import java.lang.{Class, ClassNotFoundException, NoSuchMethodException}
import java.lang.reflect.{Method, Modifier}
import java.net.{URL, URLClassLoader}
/** An object that runs another object specified by name.
*
* @author Lex Spoon
* @version 1.1, 2007/7/13
*/
object ObjectRunner {
/** Create a class loader for the specified class path */
private def makeClassLoader(classpath: List[URL]) =
new URLClassLoader(classpath.toArray, null)
/** Look up a class with a given class path. */
private def findClass(loader: ClassLoader, objectName: String)
: Option[Class[T] forSome { type T }] =
{
try {
Some(Class.forName(objectName, true, loader))
} catch {
case e: SecurityException =>
Console.println(e.getMessage)
None
case _: ClassNotFoundException =>
None
}
}
/** Check whether a class with the specified name
* exists on the specified class path. */
def classExists(classpath: List[URL], objectName: String): Boolean =
!findClass(makeClassLoader(classpath), objectName).isEmpty
/** Set the Java context class loader while executing an action */
def withContextClassLoader[T](loader: ClassLoader)(action: =>T): T = {
val oldLoader = Thread.currentThread.getContextClassLoader
try {
Thread.currentThread.setContextClassLoader(loader)
action
} finally {
Thread.currentThread.setContextClassLoader(oldLoader)
}
}
/** Run a given object, specified by name, using a
* specified classpath and argument list.
*
* @throws ClassNotFoundException
* @throws NoSuchMethodError
* @throws InvocationTargetException
*/
def run(classpath: List[URL], objectName: String, arguments: Seq[String]) {
val loader = makeClassLoader(classpath)
val clsToRun = findClass(loader, objectName) match {
case Some(cls) => cls
case None => throw new ClassNotFoundException(objectName)
}
val method = clsToRun.getMethod("main", List(classOf[Array[String]]).toArray)
if ((method.getModifiers & Modifier.STATIC) == 0)
throw new NoSuchMethodException(objectName + ".main is not static")
withContextClassLoader(loader) {
method.invoke(null, List(arguments.toArray).toArray)
}
}
}
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