feat(parser): Allow operator access to non-map, non-list objects

Closes #416

bin/parser_generator_for_spec.dart

@@ -22,6 +22,8 @@ main(arguments) {
   // node node_modules/karma/bin/karma run | grep -Eo ":XNAY:.*:XNAY:" | sed -e 's/:XNAY://g' | sed -e "s/^/'/" | sed -e "s/$/',/" | sort | uniq > missing_expressions
   injector.get(isGetter ? ParserGetterSetter : ParserGenerator).generateParser([
       "foo == 'bar' ||\nbaz",
+      "nonmap['hello']",
+      "nonmap['hello']=3",
       "this['a'].b",
       "const",
       "null",

lib/core/parser/utils.dart

@@ -77,8 +77,9 @@ getKeyed(object, key) {
     return object["$key"]; // toString dangerous?
   } else if (object == null) {
     throw new EvalError('Accessing null object');
+  } else {
+    return object[key];
   }
-  throw new EvalError("Attempted field access on a non-list, non-map");
 }
 
 /// Set a keyed element in the given [object].
@@ -90,7 +91,7 @@ setKeyed(object, key, value) {
   } else if (object is Map) {
     object["$key"] = value; // toString dangerous?
   } else {
-    throw new EvalError("Attempting to set a field on a non-list, non-map");
+    object[key] = value;
   }
   return value;
 }

test/core/parser/parser_spec.dart

@@ -139,6 +139,12 @@ main() {
         expect(eval("4 + 4 + ' str'")).toEqual("8 str");
         expect(eval("'str ' + 4 + 4")).toEqual("str 44");
       });
+
+      it('should allow keyed access on non-maps', () {
+        scope['nonmap'] = new BracketButNotMap();
+        expect(eval("nonmap['hello']")).toEqual('hello');
+        expect(eval("nonmap['hello']=3")).toEqual(3);
+      });
     });
 
     describe('error handling', () {
@@ -171,12 +177,6 @@ main() {
       });
 
 
-      it('should throw on non-list, non-map field access', () {
-        expectEval("6[3]").toThrow(errStr('Eval Error: Attempted field access on a non-list, non-map while evaling [6[3]]'));
-        expectEval("6[3]=2").toThrow(errStr('Eval Error: Attempting to set a field on a non-list, non-map while evaling [6[3]=2'));
-      });
-
-
       it('should throw on incorrect ternary operator syntax', () {
         expectEval("true?1").toThrow('Parser Error: Conditional expression true?1 requires all 3 expressions');
       });
@@ -928,6 +928,11 @@ class OverloadObject implements Map {
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
+class BracketButNotMap {
+  operator[](String name) => name;
+  operator[]=(String name, value) {}
+}
+
 class ScopeWithErrors {
   String get boo { throw "boo to you"; }
   String foo() { throw "foo to you"; }