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diff --git a/src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala b/src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala
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+++ b/src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala
@@ -0,0 +1,180 @@
+/*
+ * Copyright (c) 2014 Contributor. All rights reserved.
+ */
+package scala.tools.nsc.classpath
+
+import java.io.File
+import java.net.URL
+import scala.annotation.tailrec
+import scala.reflect.io.{ AbstractFile, FileZipArchive, ManifestResources }
+import scala.tools.nsc.Settings
+import FileUtils._
+
+/**
+ * A trait providing an optional cache for classpath entries obtained from zip and jar files.
+ * It's possible to create such a cache assuming that entries in such files won't change (at
+ * least will be the same each time we'll load classpath during the lifetime of JVM process)
+ * - unlike class and source files in directories, which can be modified and recompiled.
+ * It allows us to e.g. reduce significantly memory used by PresentationCompilers in Scala IDE
+ * when there are a lot of projects having a lot of common dependencies.
+ */
+sealed trait ZipAndJarFileLookupFactory {
+
+  private val cache = collection.mutable.Map.empty[AbstractFile, FlatClassPath]
+
+  def create(zipFile: AbstractFile, settings: Settings): FlatClassPath = {
+    if (settings.YdisableFlatCpCaching) createForZipFile(zipFile)
+    else createUsingCache(zipFile, settings)
+  }
+
+  protected def createForZipFile(zipFile: AbstractFile): FlatClassPath
+
+  private def createUsingCache(zipFile: AbstractFile, settings: Settings): FlatClassPath = cache.synchronized {
+    def newClassPathInstance = {
+      if (settings.verbose || settings.Ylogcp)
+        println(s"$zipFile is not yet in the classpath cache")
+      createForZipFile(zipFile)
+    }
+    cache.getOrElseUpdate(zipFile, newClassPathInstance)
+  }
+}
+
+/**
+ * Manages creation of flat classpath for class files placed in zip and jar files.
+ * It should be the only way of creating them as it provides caching.
+ */
+object ZipAndJarFlatClassPathFactory extends ZipAndJarFileLookupFactory {
+
+  private case class ZipArchiveFlatClassPath(zipFile: File)
+    extends ZipArchiveFileLookup[ClassFileEntryImpl]
+    with NoSourcePaths {
+
+    override def findClassFile(className: String): Option[AbstractFile] = {
+      val (pkg, simpleClassName) = PackageNameUtils.separatePkgAndClassNames(className)
+      classes(pkg).find(_.name == simpleClassName).map(_.file)
+    }
+
+    override private[nsc] def classes(inPackage: String): Seq[ClassFileEntry] = files(inPackage)
+
+    override protected def createFileEntry(file: FileZipArchive#Entry): ClassFileEntryImpl = ClassFileEntryImpl(file)
+    override protected def isRequiredFileType(file: AbstractFile): Boolean = file.isClass
+  }
+
+  /**
+   * This type of classpath is closly related to the support for JSR-223.
+   * Its usage can be observed e.g. when running:
+   * jrunscript -classpath scala-compiler.jar;scala-reflect.jar;scala-library.jar -l scala
+   * with a particularly prepared scala-library.jar. It should have all classes listed in the manifest like e.g. this entry:
+   * Name: scala/Function2$mcFJD$sp.class
+   */
+  private case class ManifestResourcesFlatClassPath(file: ManifestResources)
+    extends FlatClassPath
+    with NoSourcePaths {
+
+    override def findClassFile(className: String): Option[AbstractFile] = {
+      val (pkg, simpleClassName) = PackageNameUtils.separatePkgAndClassNames(className)
+      classes(pkg).find(_.name == simpleClassName).map(_.file)
+    }
+
+    override def asClassPathStrings: Seq[String] = Seq(file.path)
+
+    override def asURLs: Seq[URL] = file.toURLs()
+
+    import ManifestResourcesFlatClassPath.PackageFileInfo
+    import ManifestResourcesFlatClassPath.PackageInfo
+
+    /**
+     * A cache mapping package name to abstract file for package directory and subpackages of given package.
+     *
+     * ManifestResources can iterate through the collections of entries from e.g. remote jar file.
+     * We can't just specify the path to the concrete directory etc. so we can't just 'jump' into
+     * given package, when it's needed. On the other hand we can iterate over entries to get
+     * AbstractFiles, iterate over entries of these files etc.
+     *
+     * Instead of traversing a tree of AbstractFiles once and caching all entries or traversing each time,
+     * when we need subpackages of a given package or its classes, we traverse once and cache only packages.
+     * Classes for given package can be then easily loaded when they are needed.
+     */
+    private lazy val cachedPackages: collection.mutable.HashMap[String, PackageFileInfo] = {
+      val packages = collection.mutable.HashMap[String, PackageFileInfo]()
+
+      def getSubpackages(dir: AbstractFile): List[AbstractFile] =
+        (for (file <- dir if file.isPackage) yield file)(collection.breakOut)
+
+      @tailrec
+      def traverse(packagePrefix: String,
+                   filesForPrefix: List[AbstractFile],
+                   subpackagesQueue: collection.mutable.Queue[PackageInfo]): Unit = filesForPrefix match {
+        case pkgFile :: remainingFiles =>
+          val subpackages = getSubpackages(pkgFile)
+          val fullPkgName = packagePrefix + pkgFile.name
+          packages.put(fullPkgName, PackageFileInfo(pkgFile, subpackages))
+          val newPackagePrefix = fullPkgName + "."
+          subpackagesQueue.enqueue(PackageInfo(newPackagePrefix, subpackages))
+          traverse(packagePrefix, remainingFiles, subpackagesQueue)
+        case Nil if subpackagesQueue.nonEmpty =>
+          val PackageInfo(packagePrefix, filesForPrefix) = subpackagesQueue.dequeue()
+          traverse(packagePrefix, filesForPrefix, subpackagesQueue)
+        case _ =>
+      }
+
+      val subpackages = getSubpackages(file)
+      packages.put(FlatClassPath.RootPackage, PackageFileInfo(file, subpackages))
+      traverse(FlatClassPath.RootPackage, subpackages, collection.mutable.Queue())
+      packages
+    }
+
+    override private[nsc] def packages(inPackage: String): Seq[PackageEntry] = cachedPackages.get(inPackage) match {
+      case None => Seq.empty
+      case Some(PackageFileInfo(_, subpackages)) =>
+        val prefix = PackageNameUtils.packagePrefix(inPackage)
+        subpackages.map(packageFile => PackageEntryImpl(prefix + packageFile.name))
+    }
+
+    override private[nsc] def classes(inPackage: String): Seq[ClassFileEntry] = cachedPackages.get(inPackage) match {
+      case None => Seq.empty
+      case Some(PackageFileInfo(pkg, _)) =>
+        (for (file <- pkg if file.isClass) yield ClassFileEntryImpl(file))(collection.breakOut)
+    }
+
+    override private[nsc] def list(inPackage: String): FlatClassPathEntries = FlatClassPathEntries(packages(inPackage), classes(inPackage))
+  }
+
+  private object ManifestResourcesFlatClassPath {
+    case class PackageFileInfo(packageFile: AbstractFile, subpackages: Seq[AbstractFile])
+    case class PackageInfo(packageName: String, subpackages: List[AbstractFile])
+  }
+
+  override protected def createForZipFile(zipFile: AbstractFile): FlatClassPath =
+    if (zipFile.file == null) createWithoutUnderlyingFile(zipFile)
+    else ZipArchiveFlatClassPath(zipFile.file)
+
+  private def createWithoutUnderlyingFile(zipFile: AbstractFile) = zipFile match {
+    case manifestRes: ManifestResources =>
+      ManifestResourcesFlatClassPath(manifestRes)
+    case _ =>
+      val errorMsg = s"Abstract files which don't have an underlying file and are not ManifestResources are not supported. There was $zipFile"
+      throw new IllegalArgumentException(errorMsg)
+  }
+}
+
+/**
+ * Manages creation of flat classpath for source files placed in zip and jar files.
+ * It should be the only way of creating them as it provides caching.
+ */
+object ZipAndJarFlatSourcePathFactory extends ZipAndJarFileLookupFactory {
+
+  private case class ZipArchiveFlatSourcePath(zipFile: File)
+    extends ZipArchiveFileLookup[SourceFileEntryImpl]
+    with NoClassPaths {
+
+    override def asSourcePathString: String = asClassPathString
+
+    override private[nsc] def sources(inPackage: String): Seq[SourceFileEntry] = files(inPackage)
+
+    override protected def createFileEntry(file: FileZipArchive#Entry): SourceFileEntryImpl = SourceFileEntryImpl(file)
+    override protected def isRequiredFileType(file: AbstractFile): Boolean = file.isScalaOrJavaSource
+  }
+
+  override protected def createForZipFile(zipFile: AbstractFile): FlatClassPath = ZipArchiveFlatSourcePath(zipFile.file)
+}