src/jdk.scripting.nashorn/share/classes/jdk/nashorn/tools/Shell.java

*** 41,50 ****
--- 41,51 ----
  import java.util.ResourceBundle;
  import jdk.nashorn.api.scripting.NashornException;
  import jdk.nashorn.internal.codegen.Compiler;
  import jdk.nashorn.internal.codegen.Compiler.CompilationPhases;
  import jdk.nashorn.internal.ir.FunctionNode;
+ import jdk.nashorn.internal.ir.Expression;
  import jdk.nashorn.internal.ir.debug.ASTWriter;
  import jdk.nashorn.internal.ir.debug.PrintVisitor;
  import jdk.nashorn.internal.objects.Global;
  import jdk.nashorn.internal.parser.Parser;
  import jdk.nashorn.internal.runtime.Context;
*** 395,404 ****
--- 396,440 ----
      protected Object apply(final ScriptFunction target, final Object self) {
          return ScriptRuntime.apply(target, self);
      }
  
      /**
+      * Parse potentially partial code and keep track of the start of last expression.
+      * This 'partial' parsing support is meant to be used for code-completion.
+      *
+      * @param context the nashorn context
+      * @param code code that is to be parsed
+      * @return the start index of the last expression parsed in the (incomplete) code.
+      */
+     protected int getLastExpressionStart(final Context context, final String code) {
+         final int[] exprStart = { -1 };
+ 
+         final Parser p = new Parser(context.getEnv(), sourceFor("<partial_code>", code),new Context.ThrowErrorManager()) {
+             @Override
+             protected Expression expression() {
+                 exprStart[0] = this.start;
+                 return super.expression();
+             }
+ 
+             @Override
+             protected Expression assignmentExpression(final boolean noIn) {
+                 exprStart[0] = this.start;
+                 return super.expression();
+             }
+         };
+ 
+         try {
+             p.parse();
+         } catch (final Exception ignored) {
+             // throw any parser exception, but we are partial parsing anyway
+         }
+ 
+         return exprStart[0];
+     }
+ 
+ 
+     /**
       * read-eval-print loop for Nashorn shell.
       *
       * @param context the nashorn context
       * @param global  global scope object to use
       * @return return code