Add flat classpath implementation for zip and jar files

This commit adds an implementation of flat classpath which can handle
both jar and vanilla zip files. In fact there are two versions - for
a class- and a sourcepath. Both extend ZipArchiveFileLookup which
provides common logic.

They use FileZipArchive. @gkossakowski made a comparison of different
ways of handling zips and jars (e.g. using javac's ZipFileIndex). He
stated that general efficiency of FileZipArchive, taking into account
various parameters, is the best.

FileZipArchive is slightly changed. From now it allows to find the
entry for directory in all directory entries without iterating all
entries regardless of a type. Thanks to that we can simply find
a directory for a package - like in the case of DirectoryFileLookup.

There's also added possibility to cache classpath representation of
classpath elements from jar and zip files across compiler instances.
The cache is just a map AbstractFile -> FlatClassPath. It should
reduce the number of created classpath and file instances e.g. in the
case of many ScalaPresentationCompilers in Scala IDE.

To prevent the possibility to avoid a cache, caches are created as
a part of factories responsible for the creation of these types of
the flat classpath.

1 files changed, 7 insertions, 6 deletions

diff --git a/src/reflect/scala/reflect/io/ZipArchive.scala b/src/reflect/scala/reflect/io/ZipArchive.scala
index 8260189459..dc2ec848b1 100644
--- a/src/reflect/scala/reflect/io/ZipArchive.scala
+++ b/src/reflect/scala/reflect/io/ZipArchive.scala
@@ -125,14 +125,15 @@ abstract class ZipArchive(override val file: JFile) extends AbstractFile with Eq
 }
 /** ''Note:  This library is considered experimental and should not be used unless you know what you are doing.'' */
 final class FileZipArchive(file: JFile) extends ZipArchive(file) {
-  def iterator: Iterator[Entry] = {
+  lazy val (root, allDirs) = {
+    val root = new DirEntry("/")
+    val dirs = mutable.HashMap[String, DirEntry]("/" -> root)
     val zipFile = try {
       new ZipFile(file)
     } catch {
       case ioe: IOException => throw new IOException("Error accessing " + file.getPath, ioe)
     }
-    val root    = new DirEntry("/")
-    val dirs    = mutable.HashMap[String, DirEntry]("/" -> root)
+
     val enum    = zipFile.entries()
 
     while (enum.hasMoreElements) {
@@ -150,11 +151,11 @@ final class FileZipArchive(file: JFile) extends ZipArchive(file) {
         dir.entries(f.name) = f
       }
     }
-
-    try root.iterator
-    finally dirs.clear()
+    (root, dirs)
   }
 
+  def iterator: Iterator[Entry] = root.iterator
+
   def name         = file.getName
   def path         = file.getPath
   def input        = File(file).inputStream()