1 files changed, 55 insertions, 0 deletions
diff --git a/src/dotty/tools/dotc/Resident.scala b/src/dotty/tools/dotc/Resident.scala
new file mode 100644
index 000000000..d671ea259
--- /dev/null
+++ b/src/dotty/tools/dotc/Resident.scala
@@ -0,0 +1,55 @@
+package dotty.tools
+package dotc
+
+import core.Contexts.Context
+import reporting.Reporter
+import java.io.EOFException
+import scala.annotation.tailrec
+
+/** A compiler which stays resident between runs.
+ *  Usage:
+ *
+ *  > scala dotty.tools.dotc.Resident <options> <initial files>
+ *
+ *  dotc> "more options and files to compile"
+ *
+ *  ...
+ *
+ *  dotc> :reset  // reset all options to the ones passed on the command line
+ *
+ *  ...
+ *
+ *  dotc> :q     // quit
+ */
+object Resident extends Driver {
+
+  object residentCompiler extends Compiler
+
+  override def newCompiler(): Compiler = ???
+
+  override def sourcesRequired = false
+
+  private val quit = ":q"
+  private val reset = ":reset"
+
+  private def getLine() = {
+    Console.print(prompt)
+    try scala.io.StdIn.readLine() catch { case _: EOFException => quit }
+  }
+
+  final override def process(args: Array[String], rootCtx: Context): Reporter = {
+    @tailrec def loop(args: Array[String], prevCtx: Context): Reporter = {
+      var (fileNames, ctx) = setup(args, prevCtx)
+      doCompile(residentCompiler, fileNames)(ctx)
+      var nextCtx = ctx
+      var line = getLine()
+      while (line == reset) {
+        nextCtx = rootCtx
+        line = getLine()
+      }
+      if (line.startsWith(quit)) ctx.typerState.reporter
+      else loop(line split "\\s+", nextCtx)
+    }
+    loop(args, rootCtx)
+  }
+}