Implement and test nqp::getlexdyn.

src/vm/js/QAST/Compiler.nqp

@@ -1079,6 +1079,8 @@ class QAST::OperationsJS {
         } , :sideffects);
     }
 
+    add_simple_op('getlexdyn', $T_OBJ, [$T_STR], sub ($name) {"{$*BLOCK.ctx}.lookup_dynamic_from_caller($name)"});
+
     add_simple_op('captureposelems', $T_INT, [$T_OBJ]);
     add_simple_op('captureposarg', $T_OBJ, [$T_OBJ, $T_INT]);
     add_simple_op('invokewithcapture', $T_OBJ, [$T_OBJ, $T_OBJ], sub ($invokee, $capture) {

src/vm/js/nqp-runtime/runtime.js

@@ -144,6 +144,19 @@ Ctx.prototype.lookup_dynamic = function(name) {
      nqp code usually fallbacks to looking up of global */
 };
 
+Ctx.prototype.lookup_dynamic_from_caller = function(name) {
+  var ctx = this.caller;
+  while (ctx) {
+    if (ctx.hasOwnProperty(name)) {
+      return ctx[name];
+    }
+    ctx = ctx.caller;
+  }
+  return null;
+  /* Looking up of a contextual is allowed to fail,
+     nqp code usually fallbacks to looking up of global */
+};
+
 Ctx.prototype.lookup = function(name, value) {
   var ctx = this;
   while (ctx) {

t/nqp/21-contextual.t

@@ -2,7 +2,7 @@
 
 # Tests for contextual variables
 
-plan(7);
+plan(10);
 
 sub foo() { $*VAR }
 
@@ -28,3 +28,27 @@ sub foo() { $*VAR }
 }
 
 
+
+sub simple_lookup() {
+    my $foo := nqp::getlexdyn('$*fo' ~ 'o');
+    ok( $foo eq 'bar', "getting dynamic variable using getlexdyn");
+}
+
+{
+    my $*foo := "bar";
+    simple_lookup();
+}
+
+sub ignore_local() {
+    my $*foo2;
+    $*foo2 := "baz";
+    my $foo := nqp::getlexdyn('$*foo2');
+    ok( $foo eq 'bar2', "getting dynamic variable using getlexdyn gets the variable from the caller");
+    ok( nqp::isnull(nqp::getlexdyn("$*no_such")), "nqp::getlexdyn return null for missing variables");
+}
+
+{
+    my $*foo2 := "bar2";
+    ignore_local();
+}
+