From 97abbae86af0c2b508583394e088291ac8241f29 Mon Sep 17 00:00:00 2001
From: Paul Phillips <paulp@improving.org>
Date: Wed, 26 May 2010 00:03:51 +0000
Subject: Made interpreter robust against a missing class...

Made interpreter robust against a missing classpath and had it issue
informative message in such cases, as per suggestion by Razvan Cojocaru.
No review.

% java -classpath build/pack/lib/'*' scala.tools.nsc.MainGenericRunner
scala> Failed to initialize compiler: class scala.runtime.BooleanRef
not found. ** Note that as of 2.8 scala does not assume use of the java
classpath. ** For the old behavior pass -usejavacp to scala, or if using
a Settings

** object programatically, settings.usejavacp.value = true.
---
 src/compiler/scala/tools/nsc/Interpreter.scala     | 37 +++++++++++++++-------
 src/compiler/scala/tools/nsc/InterpreterLoop.scala |  7 ++--
 2 files changed, 31 insertions(+), 13 deletions(-)

(limited to 'src')

diff --git a/src/compiler/scala/tools/nsc/Interpreter.scala b/src/compiler/scala/tools/nsc/Interpreter.scala
index 868af7a4bc..128c378e23 100644
--- a/src/compiler/scala/tools/nsc/Interpreter.scala
+++ b/src/compiler/scala/tools/nsc/Interpreter.scala
@@ -75,6 +75,11 @@ import Interpreter._
 class Interpreter(val settings: Settings, out: PrintWriter) {
   repl =>
 
+  def println(x: Any) = {
+    out.println(x)
+    out.flush()
+  }
+
   /** construct an interpreter that reports to Console */
   def this(settings: Settings) = this(settings, new NewLinePrintWriter(new ConsoleWriter, true))
   def this() = this(new Settings())
@@ -108,28 +113,37 @@ class Interpreter(val settings: Settings, out: PrintWriter) {
       |}
       |""".stripMargin
 
-    val run = new _compiler.Run()
-    run compileSources List(new BatchSourceFile("<init>", source))
-    if (settings.debug.value) {
-      out println "Repl compiler initialized."
-      out.flush()
+    try {
+      new _compiler.Run() compileSources List(new BatchSourceFile("<init>", source))
+      if (isReplDebug || settings.debug.value)
+        println("Repl compiler initialized.")
+      true
+    }
+    catch {
+      case MissingRequirementError(msg) => println("""
+        |Failed to initialize compiler: %s not found.
+        |** Note that as of 2.8 scala does not assume use of the java classpath.
+        |** For the old behavior pass -usejavacp to scala, or if using a Settings
+        |** object programatically, settings.usejavacp.value = true.""".stripMargin.format(msg)
+      )
+      false
     }
-    true
   }
 
   // set up initialization future
-  private var _isInitialized: () => Boolean = () => false
+  private var _isInitialized: () => Boolean = null
   def initialize() = synchronized {
-    if (!_isInitialized())
+    if (_isInitialized == null)
       _isInitialized = scala.concurrent.ops future _initialize()
   }
 
   /** the public, go through the future compiler */
   lazy val compiler: Global = {
     initialize()
-    _isInitialized()   // blocks until it is
 
-    _compiler
+    // blocks until it is ; false means catastrophic failure
+    if (_isInitialized()) _compiler
+    else null
   }
 
   import compiler.{ Traverser, CompilationUnit, Symbol, Name, Type }
@@ -573,7 +587,8 @@ class Interpreter(val settings: Settings, out: PrintWriter) {
       else IR.Error
     }
 
-    requestFromLine(line, synthetic) match {
+    if (compiler == null) IR.Error
+    else requestFromLine(line, synthetic) match {
       case Left(result) => result
       case Right(req)   =>
         // null indicates a disallowed statement type; otherwise compile and
diff --git a/src/compiler/scala/tools/nsc/InterpreterLoop.scala b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
index ce6d3149a3..f68ce4a5b4 100644
--- a/src/compiler/scala/tools/nsc/InterpreterLoop.scala
+++ b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
@@ -355,8 +355,11 @@ class InterpreterLoop(in0: Option[BufferedReader], protected val out: PrintWrite
     def ambiguous(cmds: List[Command]) = "Ambiguous: did you mean " + cmds.map(":" + _.name).mkString(" or ") + "?"
 
     // not a command
-    if (!line.startsWith(":"))
-      return Result(true, interpretStartingWith(line))
+    if (!line.startsWith(":")) {
+      // Notice failure to create compiler
+      if (interpreter.compiler == null) return Result(false, None)
+      else return Result(true, interpretStartingWith(line))
+    }
 
     val tokens = (line drop 1 split """\s+""").toList
     if (tokens.isEmpty)
-- 
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