Repl javap decodes various synthetic names for us (fixing SI-6894)

For instance, javap -app Test is equivalent to javap Test$delayedInit$App
with the correct line and iw prepended.  This works by taking Test as a
name in scope, translating that, and then supplying the suffix.

Then javap -fun Test shows Test$$anonfun*, and for member m,
javap -fun Test#m shows Test$$anonfun$$m*.

This also works for classes and values defined in the repl.
javap -fun -raw m shows $line3.$read$$iw$$iw$$anonfun$m$1.

E.g., javap -fun scala.Enumeration obviates knowing or guessing
scala/Enumeration$$anonfun$scala$Enumeration$$populateNameMap$1.class.

Also, scala> :javap -fun scala.Array#concat
but still to do is using imported syms.

Both files and replout are supported for searching for artifacts.

The trigger is detecting the synthetic name (has an interior dollar).

Still to do, filter the output on Test#m to show only m.

Need a way to explore the list of artifacts; ideally, related symbols
would be available reflectively.

Prefer companion class to object, otherwise it's not showable;
for object, require dollar when both exist.

A JavapTest is supplied that is a ReplTest that asserts something about
its output instead of printing it.

3 files changed, 258 insertions, 27 deletions

diff --git a/src/compiler/scala/tools/nsc/interpreter/IMain.scala b/src/compiler/scala/tools/nsc/interpreter/IMain.scala
index 36f012229e..4f23d9902e 100644
--- a/src/compiler/scala/tools/nsc/interpreter/IMain.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/IMain.scala
@@ -953,7 +953,7 @@ class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends
    */
   def tryTwice(op: => Symbol): Symbol = exitingTyper(op) orElse exitingFlatten(op)
 
-  def symbolOfIdent(id: String): Symbol  = symbolOfTerm(id) orElse symbolOfType(id)
+  def symbolOfIdent(id: String): Symbol  = symbolOfType(id) orElse symbolOfTerm(id)
   def symbolOfType(id: String): Symbol   = tryTwice(replScope lookup (id: TypeName))
   def symbolOfTerm(id: String): Symbol   = tryTwice(replScope lookup (id: TermName))
   def symbolOfName(id: Name): Symbol     = replScope lookup id
diff --git a/src/compiler/scala/tools/util/Javap.scala b/src/compiler/scala/tools/util/Javap.scala
index 269cfa5dd4..b39d5a5d89 100644
--- a/src/compiler/scala/tools/util/Javap.scala
+++ b/src/compiler/scala/tools/util/Javap.scala
@@ -12,15 +12,18 @@ import scala.tools.nsc.interpreter.IMain
 import java.io.{ ByteArrayInputStream, CharArrayWriter, FileNotFoundException, InputStream,
                  PrintWriter, Writer }
 import java.util.{ Locale }
+import java.util.regex.Pattern
 import javax.tools.{ Diagnostic, DiagnosticCollector, DiagnosticListener,
                      ForwardingJavaFileManager, JavaFileManager, JavaFileObject,
                      SimpleJavaFileObject, StandardLocation }
-import scala.tools.nsc.io.File
+import scala.reflect.io.{ AbstractFile, Directory, File, Path }
+import java.io.{File => JFile}
 import scala.io.Source
 import scala.util.{ Try, Success, Failure }
 import scala.util.Properties.lineSeparator
 import scala.collection.JavaConverters
 import scala.collection.generic.Clearable
+import java.net.URL
 import scala.language.reflectiveCalls
 
 import Javap._
@@ -47,6 +50,7 @@ class JavapClass(
   intp: Option[IMain] = None
 ) extends Javap {
   import JavapTool.ToolArgs
+  import JavapClass._
 
   lazy val tool = JavapTool()
 
@@ -58,7 +62,10 @@ class JavapClass(
     val (options, claases) = args partition (s => (s startsWith "-") && s.length > 1)
     val (flags, upgraded) = upgrade(options)
     if (flags.help || claases.isEmpty) List(JpResult(JavapTool.helper(printWriter)))
-    else tool(flags.raw, upgraded)(claases map (claas => claas -> bytesFor(claas)))
+    else {
+      val targets = if (flags.fun) FunFinder(loader, intp).funs(claases) else claases
+      tool(flags.raw, upgraded)(targets map (claas => claas -> bytesFor(claas, flags.app)))
+    }
   }
 
   /** Cull our tool options. */
@@ -67,9 +74,16 @@ class JavapClass(
     case (t,s)                => (t, JavapTool.DefaultOptions)
   }
 
-  private def bytesFor(path: String) = Try {
+  /** Find bytes. Handle "-", "-app", "Foo#bar" (by ignoring member). */
+  private def bytesFor(path: String, app: Boolean) = Try {
     def last = intp.get.mostRecentVar  // fail if no intp
-    val bytes = findBytes(if (path == "-") last else path)
+    def req = if (path == "-") last else path.splitHashMember._1
+    def asAppBody(s: String) = {
+      val (cls, fix) = s.splitSuffix
+      s"${cls}$$delayedInit$$body${fix}"
+    }
+    def todo = if (app) asAppBody(req) else req
+    val bytes = findBytes(todo)
     if (bytes.isEmpty) throw new FileNotFoundException(s"Could not find class bytes for '${path}'")
     else bytes
   }
@@ -79,30 +93,57 @@ class JavapClass(
   /** Assume the string is a path and try to find the classfile
    *  it represents.
    */
-  def tryFile(path: String): Option[Array[Byte]] = {
-    val file =
-      if (path.endsWith(".class")) path
-      else path.replace('.', '/') + ".class"
-    (Try (File(file)) filter (_.exists) map (_.toByteArray)).toOption
-  }
+  def tryFile(path: String): Option[Array[Byte]] =
+    (Try (File(path.asClassResource)) filter (_.exists) map (_.toByteArray)).toOption
+
   /** Assume the string is a fully qualified class name and try to
    *  find the class object it represents.
+   *  There are other symbols of interest, too:
+   *  - a definition that is wrapped in an enclosing class
+   *  - a synthetic that is not in scope but its associated class is
    */
   def tryClass(path: String): Array[Byte] = {
-    def pathology(p: String) =
-      if (p endsWith ".class") (p dropRight 6).replace('/', '.')
-      else p
-    def load(name: String) = loader classBytes pathology(name)
+    def load(name: String) = loader classBytes name
+    def loadable(name: String) = loader resourceable name
+    // if path has an interior dollar, take it as a synthetic
+    // if the prefix up to the dollar is a symbol in scope,
+    // result is the translated prefix + suffix
+    def desynthesize(s: String) = {
+      val i = s indexOf '$'
+      if (0 until s.length - 1 contains i) {
+        val name = s substring (0, i)
+        val sufx = s substring i
+        val tran = intp flatMap (_ translatePath name)
+        def loadableOrNone(strip: Boolean) = {
+          def suffix(strip: Boolean)(x: String) =
+            (if (strip && (x endsWith "$")) x.init else x) + sufx
+          val res = tran map (suffix(strip) _)
+          if (res.isDefined && loadable(res.get)) res else None
+        }
+        // try loading translated+suffix
+        val res = loadableOrNone(false)
+        // some synthetics lack a dollar, (e.g., suffix = delayedInit$body)
+        // so as a hack, if prefix$$suffix fails, also try prefix$suffix
+        if (res.isDefined) res else loadableOrNone(true)
+      } else None
+    }
+    val p = path.asClassName   // scrub any suffix
     // if repl, translate the name to something replish
-    if (intp.isDefined) {
-      val claas = load(intp.get.translatePath(path) getOrElse path)
-      if (!claas.isEmpty) claas
+    // (for translate, would be nicer to get the sym and ask .isClass,
+    // instead of translatePath and then asking did I get a class back)
+    val q = if (intp.isEmpty) p else (
+      // only simple names get the scope treatment
+      Some(p) filter (_ contains '.')
+      // take path as a Name in scope
+      orElse (intp flatMap (_ translatePath p) filter loadable)
       // take path as a Name in scope and find its enclosing class
-      else intp.get.translateEnclosingClass(path) match {
-        case Some(encl) => load(encl)
-        case _          => claas      // empty
-      }
-    } else load(path)
+      orElse (intp flatMap (_ translateEnclosingClass p) filter loadable)
+      // take path as a synthetic derived from some Name in scope
+      orElse desynthesize(p)
+      // just try it plain
+      getOrElse p
+    )
+    load(q)
   }
 
   abstract class JavapTool {
@@ -245,7 +286,7 @@ class JavapClass(
     }
     val writer = new CharArrayWriter
     def fileManager(inputs: Seq[Input]) = new JavapFileManager(inputs)()
-    def showable(raw: Boolean): Showable = {
+    def showable(raw: Boolean, target: String): Showable = {
       val written = {
         writer.flush()
         val w = writer.toString
@@ -261,7 +302,28 @@ class JavapClass(
           if (raw && intp.isDefined) intp.get withoutUnwrapping { writeLines() }
           else writeLines()
         private def writeLines() {
-          for (line <- Source.fromString(mw).getLines) printWriter write line+lineSeparator
+          // take Foo# as Foo#apply for purposes of filtering. Useful for -fun Foo#
+          val filterOn = target.splitHashMember._2 map { s => if (s.isEmpty) "apply" else s }
+          var filtering = false   // true if in region matching filter
+          // true to output
+          def checkFilter(line: String) = if (filterOn.isEmpty) true else {
+            def isOurMethod = {
+              val lparen = line.lastIndexOf('(')
+              val blank = line.lastIndexOf(' ', lparen)
+              (blank >= 0 && line.substring(blank+1, lparen) == filterOn.get)
+            }
+            filtering = if (filtering) {
+              // next blank line terminates section
+              line.trim.nonEmpty
+            } else {
+              // cheap heuristic, todo maybe parse for the java sig.
+              // method sigs end in paren semi
+              line.endsWith(");") && isOurMethod
+            }
+            filtering
+          }
+          for (line <- Source.fromString(mw).getLines; if checkFilter(line))
+            printWriter write line+lineSeparator
           printWriter.flush()
         }
       }
@@ -279,7 +341,7 @@ class JavapClass(
       Try {
         task(options, Seq(claas), inputs).call()
       } map {
-        case true => JpResult(showable(raw))
+        case true => JpResult(showable(raw, claas))
         case _    => JpResult(reporter.reportable(raw))
       } recoverWith {
         case e: java.lang.reflect.InvocationTargetException => e.getCause match {
@@ -345,11 +407,13 @@ class JavapClass(
       }
     }
 
-    case class ToolArgs(raw: Boolean = false, help: Boolean = false)
+    case class ToolArgs(raw: Boolean = false, help: Boolean = false, app: Boolean = false, fun: Boolean = false)
 
     object ToolArgs {
       def fromArgs(args: Seq[String]): (ToolArgs, Seq[String]) = ((ToolArgs(), Seq[String]()) /: (args flatMap massage)) {
         case ((t,others), s) => s match {
+          case "-fun"   => (t copy (fun=true), others)
+          case "-app"   => (t copy (app=true), others)
           case "-help"  => (t copy (help=true), others)
           case "-raw"   => (t copy (raw=true), others)
           case _        => (t, others :+ s)
@@ -361,6 +425,8 @@ class JavapClass(
       "usage"       -> ":javap [opts] [path or class or -]...",
       "-help"       -> "Prints this help message",
       "-raw"        -> "Don't unmangle REPL names",
+      "-app"        -> "Show the DelayedInit body of Apps",
+      "-fun"        -> "Show anonfuns for class or Class#method",
       "-verbose/-v" -> "Stack size, number of locals, method args",
       "-private/-p" -> "Private classes and members",
       "-package"    -> "Package-private classes and members",
@@ -428,6 +494,145 @@ object JavapClass {
     printWriter: PrintWriter = new PrintWriter(System.out, true),
     intp: Option[IMain] = None
   ) = new JavapClass(loader, printWriter, intp)
+
+  // We enjoy flexibility in specifying either a fully-qualified class name com.acme.Widget
+  // or a resource path com/acme/Widget.class; but not widget.out
+  implicit class MaybeClassLike(val s: String) extends AnyVal {
+    /* private[this] final val suffix = ".class" */
+    private def suffix = ".class"
+    def asClassName = (s stripSuffix suffix).replace('/', '.')
+    def asClassResource = if (s endsWith suffix) s else s.replace('.', '/') + suffix
+    def splitSuffix: (String, String) = if (s endsWith suffix) (s dropRight suffix.length, suffix) else (s, "")
+    def strippingSuffix(f: String => String): String =
+      if (s endsWith suffix) f(s dropRight suffix.length) else s
+    // e.g. Foo#bar. Foo# yields zero-length member part.
+    def splitHashMember: (String, Option[String]) = {
+      val i = s lastIndexOf '#'
+      if (i < 0) (s, None)
+      //else if (i >= s.length - 1) (s.init, None)
+      else (s take i, Some(s drop i+1))
+    }
+  }
+  implicit class ClassLoaderOps(val cl: ClassLoader) extends AnyVal {
+    private def parentsOf(x: ClassLoader): List[ClassLoader] = if (x == null) Nil else x :: parentsOf(x.getParent)
+    def parents: List[ClassLoader] = parentsOf(cl)
+    /* all file locations */
+    def locations = {
+      def alldirs = parents flatMap (_ match {
+        case ucl: ScalaClassLoader.URLClassLoader => ucl.classPathURLs
+        case jcl: java.net.URLClassLoader         => jcl.getURLs
+        case _ => Nil
+      })
+      val dirs = for (d <- alldirs; if d.getProtocol == "file") yield Path(new JFile(d.toURI))
+      dirs
+    }
+    /* only the file location from which the given class is loaded */
+    def locate(k: String): Option[Path] = {
+      Try {
+        (cl loadClass k).getProtectionDomain.getCodeSource.getLocation
+      } match {
+        case Success(null)              => None
+        case Success(loc) if loc.isFile => Some(Path(new JFile(loc.toURI)))
+        case _                          => None
+      }
+    }
+    /* would classBytes succeed with a nonempty array */
+    def resourceable(className: String): Boolean = cl.getResource(className.asClassResource) != null
+  }
+  implicit class PathOps(val p: Path) extends AnyVal {
+    import scala.tools.nsc.io.Jar
+    def isJar = Jar isJarOrZip p
+  }
+  implicit class URLOps(val url: URL) extends AnyVal {
+    def isFile: Boolean = url.getProtocol == "file"
+  }
+  object FunFinder {
+    def apply(loader: ScalaClassLoader, intp: Option[IMain]) = new FunFinder(loader, intp)
+  }
+  class FunFinder(loader: ScalaClassLoader, intp: Option[IMain]) {
+
+    // class k, candidate f without prefix
+    def isFunOfClass(k: String, f: String) = {
+      val p = (s"${Pattern quote k}\\$$+anonfun").r
+      (p findPrefixOf f).nonEmpty
+    }
+    // class k, candidate f without prefix, method m
+    def isFunOfMethod(k: String, m: String, f: String) = {
+      val p = (s"${Pattern quote k}\\$$+anonfun\\$$${Pattern quote m}\\$$").r
+      (p findPrefixOf f).nonEmpty
+    }
+    def isFunOfTarget(k: String, m: Option[String], f: String) =
+      if (m.isEmpty) isFunOfClass(k, f)
+      else isFunOfMethod(k, m.get, f)
+    def listFunsInAbsFile(k: String, m: Option[String], d: AbstractFile) = {
+      for (f <- d; if !f.isDirectory && isFunOfTarget(k, m, f.name)) yield f.name
+    }
+    // path prefix p, class k, dir d
+    def listFunsInDir(p: String, k: String, m: Option[String])(d: Directory) = {
+      val subdir  = Path(p)
+      for (f <- (d / subdir).toDirectory.list; if f.isFile && isFunOfTarget(k, m, f.name))
+        yield f.name
+    }
+    // path prefix p, class k, jar file f
+    def listFunsInJar(p: String, k: String, m: Option[String])(f: File) = {
+      import java.util.jar.JarEntry
+      import scala.tools.nsc.io.Jar
+      def maybe(e: JarEntry) = {
+        val (path, name) = {
+          val parts = e.getName split "/"
+          if (parts.length < 2) ("", e.getName)
+          else (parts.init mkString "/", parts.last)
+        }
+        if (path == p && isFunOfTarget(k, m, name)) Some(name) else None
+      }
+      (new Jar(f) map maybe).flatten
+    }
+    def loadable(name: String) = loader resourceable name
+    // translated class, optional member, whether it is repl output
+    def translate(s: String): (String, Option[String], Boolean) = {
+      val (k0, m0) = s.splitHashMember
+      val member = m0 filter (_.nonEmpty)  // take Foo# as no member, not ""
+      // class is either something replish or available to loader
+      // $line.$read$$etc$Foo#member
+      ((intp flatMap (_ translatePath k0) filter (loadable) map ((_, member, true)))
+      // s = "f" and $line.$read$$etc$#f is what we're after, ignoring any #member
+      orElse (intp flatMap (_ translateEnclosingClass k0) map ((_, Some(s), true)))
+      getOrElse (k0, member, false))
+    }
+    /** Find the classnames of anonfuns associated with k,
+     *  where k may be an available class or a symbol in scope.
+     */
+    def funsOf(k0: String): Seq[String] = {
+      // class is either something replish or available to loader
+      val (k, member, isReplish) = translate(k0)
+      val splat   = k split "\\."
+      val name    = splat.last
+      val prefix  = if (splat.length > 1) splat.init mkString "/" else ""
+      val pkg     = if (splat.length > 1) splat.init mkString "." else ""
+      def packaged(s: String) = if (pkg.isEmpty) s else s"$pkg.$s"
+      // is this translated path in (usually virtual) repl outdir? or loadable from filesystem?
+      val fs = if (isReplish) {
+        def outed(d: AbstractFile, p: Seq[String]): Option[AbstractFile] = {
+          if (p.isEmpty) Option(d)
+          else Option(d.lookupName(p.head, true)) flatMap (f => outed(f, p.tail))
+        }
+        outed(intp.get.replOutput.dir, splat.init) map { d =>
+          listFunsInAbsFile(name, member, d) map packaged
+        }
+      } else {
+        loader locate k map { w =>
+          if (w.isDirectory) listFunsInDir(prefix, name, member)(w.toDirectory) map packaged
+          else if (w.isJar) listFunsInJar(prefix, name, member)(w.toFile) map packaged
+          else Nil
+        }
+      }
+      fs match {
+        case Some(xs) => xs.to[Seq]     // maybe empty
+        case None     => Seq(k0)        // just bail on fail
+      }
+    }
+    def funs(ks: Seq[String]) = ks flatMap funsOf _
+  }
 }
 
 object Javap {
diff --git a/src/partest/scala/tools/partest/JavapTest.scala b/src/partest/scala/tools/partest/JavapTest.scala
new file mode 100644
index 0000000000..3cb3dc6ca8
--- /dev/null
+++ b/src/partest/scala/tools/partest/JavapTest.scala
@@ -0,0 +1,26 @@
+
+package scala.tools.partest
+
+import scala.util.{Try,Success,Failure}
+import java.lang.System.{out => sysout}
+
+/** A trait for testing repl's javap command
+ *  or possibly examining its output.
+ */
+abstract class JavapTest extends ReplTest {
+
+  /** Your Assertion Here, whatever you want to bejahen.
+   *  Assertions must be satisfied by all flavors of javap
+   *  and should not be fragile with respect to compiler output.
+   */
+  def yah(res: Seq[String]): Boolean
+
+  def baddies = List(":javap unavailable", ":javap not yet working")
+
+  // give it a pass if javap is broken
+  override def show() = try {
+    val res = eval().toSeq
+    val unsupported = res exists (s => baddies exists (s contains _))
+    assert ((unsupported || yah(res)), res.mkString("","\n","\n"))
+  } catch { case ae: AssertionError => ae.printStackTrace(sysout) }
+}