Integrate flat classpath with the compiler

This commit integrates with the compiler the whole flat classpath
representation build next to the recursive one as an alternative.

From now flat classpath really works and can be turned on. There's
added flag -YclasspathImpl with two options: recursive (the default
one) and flat.

It was needed to make the dynamic dispatch to the particular
classpath representation according to the chosen type of a classpath
representation.

There's added PathResolverFactory which is used instead of a concrete
implementation of a path resolver. It turned out that only a small
subset of path resolvers methods is used outside this class in Scala
sources. Therefore, PathResolverFactory returns an instance of a base
interface PathResolverResult providing only these used methods.

PathResolverFactory in combination with matches in some other places
ensures that in all places using classpath we create/get the proper
representation.

Also the classPath method in Global is modified to use the dynamic
dispatch. This is very important change as a return type changed to
the base ClassFileLookup providing subset of old ClassPath public
methods. It can be problematic if someone was using in his project
the explicit ClassPath type or public methods which are not provided
via ClassFileLookup. I tested flat classpath with sbt and Scala IDE
and there were no problems. Also was looking at sources of some other
projects like e.g. Scala plugin for IntelliJ and there shouldn't be
problems, I think, but it would be better to check these changes
using the community build.

Scalap's Main.scala is changed to be able to use both implementations
and also to use flags related to the classpath implementation.

The classpath invalidation is modified to work properly with the old
(recursive) classpath representation after changes made in a Global.
In the case of the attempt to use the invalidation for the flat cp it
just throws exception with a message that the flat one currently
doesn't support the invalidation. And also that's why the partest's
test for the invalidation has been changed to use (always) the old
implementation. There's added an adequate comment with TODO to this
file.

There's added partest test generating various dependencies
(directories, zips and jars with sources and class files) and testing
whether the compilation and further running an application works
correctly, when there are these various types of entries specified as
-classpath and -sourcepath. It should be a good approximation of real
use cases.

1 files changed, 33 insertions, 11 deletions

diff --git a/src/compiler/scala/tools/util/PathResolver.scala b/src/compiler/scala/tools/util/PathResolver.scala
index 797abc085c..315476953d 100644
--- a/src/compiler/scala/tools/util/PathResolver.scala
+++ b/src/compiler/scala/tools/util/PathResolver.scala
@@ -9,7 +9,7 @@ package util
 
 import java.net.URL
 import scala.tools.reflect.WrappedProperties.AccessControl
-import scala.tools.nsc.{ Settings }
+import scala.tools.nsc.Settings
 import scala.tools.nsc.util.{ ClassFileLookup, ClassPath, JavaClassPath }
 import scala.reflect.io.{ File, Directory, Path, AbstractFile }
 import scala.reflect.runtime.ReflectionUtils
@@ -17,6 +17,7 @@ import ClassPath.{ JavaContext, DefaultJavaContext, join, split }
 import PartialFunction.condOpt
 import scala.language.postfixOps
 import scala.tools.nsc.classpath.{ AggregateFlatClassPath, ClassPathFactory, FlatClassPath, FlatClassPathFactory }
+import scala.tools.nsc.settings.ClassPathRepresentationType
 
 // Loosely based on the draft specification at:
 // https://wiki.scala-lang.org/display/SIW/Classpath
@@ -172,7 +173,7 @@ object PathResolver {
       !ReflectionUtils.scalacShouldntLoadClassfile(name)
   }
 
-  // called from scalap
+  @deprecated("This method is no longer used be scalap and will be deleted", "2.11.5")
   def fromPathString(path: String, context: JavaContext = DefaultJavaContext): JavaClassPath = {
     val s = new Settings()
     s.classpath.value = path
@@ -183,24 +184,35 @@ object PathResolver {
    *  If there are arguments, show those in Calculated as if those options had been
    *  given to a scala runner.
    */
-  def main(args: Array[String]): Unit = {
+  def main(args: Array[String]): Unit =
     if (args.isEmpty) {
       println(Environment)
       println(Defaults)
-    }
-    else {
+    } else {
       val settings = new Settings()
       val rest = settings.processArguments(args.toList, processAll = false)._2
-      val pr = new PathResolver(settings)
-      println(" COMMAND: 'scala %s'".format(args.mkString(" ")))
+      val pr = PathResolverFactory.create(settings)
+      println("COMMAND: 'scala %s'".format(args.mkString(" ")))
       println("RESIDUAL: 'scala %s'\n".format(rest.mkString(" ")))
-      pr.result.show()
+
+      pr.result match {
+        case cp: JavaClassPath =>
+          cp.show()
+        case cp: AggregateFlatClassPath =>
+          println(s"ClassPath has ${cp.aggregates.size} entries and results in:\n${cp.asClassPathStrings}")
+      }
     }
-  }
+}
+
+trait PathResolverResult {
+  def result: ClassFileLookup[AbstractFile]
+
+  def resultAsURLs: Seq[URL] = result.asURLs
 }
 
 abstract class PathResolverBase[BaseClassPathType <: ClassFileLookup[AbstractFile], ResultClassPathType <: BaseClassPathType]
-(settings: Settings, classPathFactory: ClassPathFactory[BaseClassPathType]) {
+(settings: Settings, classPathFactory: ClassPathFactory[BaseClassPathType])
+  extends PathResolverResult {
 
   import PathResolver.{ AsLines, Defaults, ppcp }
 
@@ -304,7 +316,8 @@ abstract class PathResolverBase[BaseClassPathType <: ClassFileLookup[AbstractFil
     cp
   }
 
-  def asURLs: List[URL] = result.asURLs.toList
+  @deprecated("Use resultAsURLs instead of this one", "2.11.5")
+  def asURLs: List[URL] = resultAsURLs.toList
 
   protected def computeResult(): ResultClassPathType
 }
@@ -328,3 +341,12 @@ class FlatClassPathResolver(settings: Settings, flatClassPathFactory: ClassPathF
 
   override protected def computeResult(): AggregateFlatClassPath = AggregateFlatClassPath(containers.toIndexedSeq)
 }
+
+object PathResolverFactory {
+
+  def create(settings: Settings): PathResolverResult =
+    settings.YclasspathImpl.value match {
+      case ClassPathRepresentationType.Flat => new FlatClassPathResolver(settings)
+      case ClassPathRepresentationType.Recursive => new PathResolver(settings)
+    }
+}