Improve the evaluate requests (#2583)

Currently it evaluates the given expression in the context of the top most stack frame.
The expression should access to any variables and arguments that are in the scope chain.
Implement the eval_at request with the level of the scope chain as a further argument.

JerryScript-DCO-1.0-Signed-off-by: Robert Sipka rsipka.uszeged@partner.samsung.com

jerry-debugger/jerry_client.py

@@ -171,6 +171,29 @@ class DebuggerPrompt(Cmd):
         self.stop = True
     do_e = do_eval
 
+    def do_eval_at(self, args):
+        """ Evaluate JavaScript source code at a scope chain level """
+
+        code = ''
+        index = 0
+        try:
+            args = args.split(" ", 1)
+
+            index = int(args[0])
+
+            if len(args) == 2:
+                code = args[1]
+
+            if index < 0 or index > 65535:
+                raise ValueError("Invalid scope chain index: %d (must be between 0 and 65535)" % index)
+
+        except ValueError as val_errno:
+            print("Error: %s" % (val_errno))
+            return
+
+        self.debugger.eval_at(code, index)
+        self.stop = True
+
     def do_memstats(self, _):
         """ Memory statistics """
         self.debugger.memstats()