From 3a255fbf0f673fdaebe5cf04d4a78aa4d276372a Mon Sep 17 00:00:00 2001
From: Raphael Jolly <rjolly@users.sourceforge.net>
Date: Thu, 21 May 2020 22:46:10 +0200
Subject: [PATCH] Script engine : implement eval(reader)

---
 .../src/dotty/tools/repl/ScriptEngine.scala     | 17 +++++++++++++++--
 tests/run-with-compiler/scripting.check         |  1 +
 tests/run-with-compiler/scripting.scala         |  1 +
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/compiler/src/dotty/tools/repl/ScriptEngine.scala b/compiler/src/dotty/tools/repl/ScriptEngine.scala
index 786279ff5a07..ac10be7f4574 100644
--- a/compiler/src/dotty/tools/repl/ScriptEngine.scala
+++ b/compiler/src/dotty/tools/repl/ScriptEngine.scala
@@ -1,7 +1,7 @@
 package dotty.tools
 package repl
 
-import java.io.Reader
+import java.io.{Reader, StringWriter}
 import javax.script.{AbstractScriptEngine, Bindings, ScriptContext, ScriptEngine => JScriptEngine, ScriptEngineFactory, ScriptException, SimpleBindings}
 import dotc.core.StdNames.str
 
@@ -44,7 +44,20 @@ class ScriptEngine extends AbstractScriptEngine {
   }
 
   @throws[ScriptException]
-  def eval(reader: Reader, context: ScriptContext): Object = throw new UnsupportedOperationException
+  def eval(reader: Reader, context: ScriptContext): Object = eval(stringFromReader(reader), context)
+
+  private val buffer = new Array[Char](8192)
+
+  def stringFromReader(in: Reader) = {
+    val out = new StringWriter
+    var n = in.read(buffer)
+    while (n > -1) {
+      out.write(buffer, 0, n)
+      n = in.read(buffer)
+    }
+    in.close
+    out.toString
+  }
 }
 
 object ScriptEngine {
diff --git a/tests/run-with-compiler/scripting.check b/tests/run-with-compiler/scripting.check
index daaac9e30302..bda709ecfb47 100644
--- a/tests/run-with-compiler/scripting.check
+++ b/tests/run-with-compiler/scripting.check
@@ -1,2 +1,3 @@
 42
 42
+42
diff --git a/tests/run-with-compiler/scripting.scala b/tests/run-with-compiler/scripting.scala
index 27d13cba601c..b42fd714e05a 100644
--- a/tests/run-with-compiler/scripting.scala
+++ b/tests/run-with-compiler/scripting.scala
@@ -4,5 +4,6 @@ object Test {
     val e = m.getEngineByName("scala")
     println(e.eval("42"))
     println(e.eval("Some(42)").asInstanceOf[Option[Int]].get)
+    println(e.eval(new java.io.StringReader("42")))
   }
 }