Create dedicated path resolver for the flat classpath representation

This commit adds dedicated FlatClassPathResolver loading classpath
entries as FlatClassPath.

Most of the common logic from PathResolver for the old classpath has
been moved to the base, separate class which isn't dependent on
a particular classpath representation. Thanks to that it was possible
to reuse it when creating an adequate path resolver for the flat
classpath representation.

This change doesn't modify the way the compiler works. It also
doesn't change nothing from the perspective of someone who already
uses PathResolver in some project or even extends it - at least as
long as he/she doesn't need to use flat classpath.

There are also added JUnit tests inter alia comparing entries created
using the old and the new classpath representations (whether the flat
one created using the new path resolver returns the same entries as
the recursive one).

1 files changed, 36 insertions, 11 deletions

diff --git a/src/compiler/scala/tools/util/PathResolver.scala b/src/compiler/scala/tools/util/PathResolver.scala
index 5526660509..797abc085c 100644
--- a/src/compiler/scala/tools/util/PathResolver.scala
+++ b/src/compiler/scala/tools/util/PathResolver.scala
@@ -7,14 +7,16 @@ package scala
 package tools
 package util
 
+import java.net.URL
 import scala.tools.reflect.WrappedProperties.AccessControl
 import scala.tools.nsc.{ Settings }
-import scala.tools.nsc.util.{ ClassPath, JavaClassPath }
+import scala.tools.nsc.util.{ ClassFileLookup, ClassPath, JavaClassPath }
 import scala.reflect.io.{ File, Directory, Path, AbstractFile }
 import scala.reflect.runtime.ReflectionUtils
 import ClassPath.{ JavaContext, DefaultJavaContext, join, split }
 import PartialFunction.condOpt
 import scala.language.postfixOps
+import scala.tools.nsc.classpath.{ AggregateFlatClassPath, ClassPathFactory, FlatClassPath, FlatClassPathFactory }
 
 // Loosely based on the draft specification at:
 // https://wiki.scala-lang.org/display/SIW/Classpath
@@ -197,12 +199,10 @@ object PathResolver {
   }
 }
 
-class PathResolver(settings: Settings, context: JavaContext) {
-  import PathResolver.{ Defaults, Environment, AsLines, MkLines, ppcp }
+abstract class PathResolverBase[BaseClassPathType <: ClassFileLookup[AbstractFile], ResultClassPathType <: BaseClassPathType]
+(settings: Settings, classPathFactory: ClassPathFactory[BaseClassPathType]) {
 
-  def this(settings: Settings) = this(settings,
-      if (settings.YnoLoadImplClass) PathResolver.NoImplClassJavaContext
-      else DefaultJavaContext)
+  import PathResolver.{ AsLines, Defaults, ppcp }
 
   private def cmdLineOrElse(name: String, alt: String) = {
     (commandLineFor(name) match {
@@ -232,6 +232,7 @@ class PathResolver(settings: Settings, context: JavaContext) {
     def javaUserClassPath   = if (useJavaClassPath) Defaults.javaUserClassPath else ""
     def scalaBootClassPath  = cmdLineOrElse("bootclasspath", Defaults.scalaBootClassPath)
     def scalaExtDirs        = cmdLineOrElse("extdirs", Defaults.scalaExtDirs)
+
     /** Scaladoc doesn't need any bootstrapping, otherwise will create errors such as:
      * [scaladoc] ../scala-trunk/src/reflect/scala/reflect/macros/Reifiers.scala:89: error: object api is not a member of package reflect
      * [scaladoc] case class ReificationException(val pos: reflect.api.PositionApi, val msg: String) extends Throwable(msg)
@@ -256,10 +257,10 @@ class PathResolver(settings: Settings, context: JavaContext) {
       else sys.env.getOrElse("CLASSPATH", ".")
     )
 
-    import context._
+    import classPathFactory._
 
     // Assemble the elements!
-    def basis = List[Traversable[ClassPath[AbstractFile]]](
+    def basis = List[Traversable[BaseClassPathType]](
       classesInPath(javaBootClassPath),             // 1. The Java bootstrap class path.
       contentsOfDirsInPath(javaExtDirs),            // 2. The Java extension class path.
       classesInExpandedPath(javaUserClassPath),     // 3. The Java application class path.
@@ -288,8 +289,10 @@ class PathResolver(settings: Settings, context: JavaContext) {
 
   def containers = Calculated.containers
 
-  lazy val result = {
-    val cp = new JavaClassPath(containers.toIndexedSeq, context)
+  import PathResolver.MkLines
+
+  def result: ResultClassPathType = {
+    val cp = computeResult()
     if (settings.Ylogcp) {
       Console print f"Classpath built from ${settings.toConciseString} %n"
       Console print s"Defaults: ${PathResolver.Defaults}"
@@ -301,5 +304,27 @@ class PathResolver(settings: Settings, context: JavaContext) {
     cp
   }
 
-  def asURLs = result.asURLs
+  def asURLs: List[URL] = result.asURLs.toList
+
+  protected def computeResult(): ResultClassPathType
+}
+
+class PathResolver(settings: Settings, context: JavaContext)
+  extends PathResolverBase[ClassPath[AbstractFile], JavaClassPath](settings, context) {
+
+  def this(settings: Settings) =
+    this(settings,
+      if (settings.YnoLoadImplClass) PathResolver.NoImplClassJavaContext
+      else DefaultJavaContext)
+
+  override protected def computeResult(): JavaClassPath =
+    new JavaClassPath(containers.toIndexedSeq, context)
+}
+
+class FlatClassPathResolver(settings: Settings, flatClassPathFactory: ClassPathFactory[FlatClassPath])
+  extends PathResolverBase[FlatClassPath, AggregateFlatClassPath](settings, flatClassPathFactory) {
+
+  def this(settings: Settings) = this(settings, new FlatClassPathFactory(settings))
+
+  override protected def computeResult(): AggregateFlatClassPath = AggregateFlatClassPath(containers.toIndexedSeq)
 }