Merge pull request beeware#546 from Nurdok/feature/reversed

Implement 'reversed' for custom __reversed__
kunparekh18 · May 25, 2017 · e6af8ac · e6af8ac
2 parents 35fafaf + a946f8a
commit e6af8ac
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Showing 2 changed files with 15 additions and 2 deletions.
diff --git a/batavia/builtins/reversed.js b/batavia/builtins/reversed.js
@@ -1,9 +1,12 @@
 var exceptions = require('../core').exceptions
 var types = require('../types')
+var callables = require('../core').callables
 
 function reversed(args, kwargs) {
  var iterable = args[0]
- if (types.isinstance(iterable, [types.List, types.Tuple])) {
+ if (iterable.__reversed__) {
+ return callables.call_method(iterable, '__reversed__', [])
+ } else if (iterable.__len__ && iterable.__getitem__) {
  var new_iterable = iterable.slice(0)
  new_iterable.reverse()
  return new types.List(new_iterable)

diff --git a/tests/builtins/test_reversed.py b/tests/builtins/test_reversed.py
@@ -3,11 +3,21 @@
 
 class ReversedTests(TranspileTestCase):
 
- def test_reverse_list(self):
+ def test_reversed_list(self):
  self.assertCodeExecution("""
  print(list(reversed([1,2,3])))
  """)
 
+ def test_reversed_dunder_reversed(self):
+ self.assertCodeExecution("""
+ class Foo(object):
+ def __reversed__(self):
+ return iter([1, 2, 3])
+ 
+ f = Foo()
+ print(list(reversed(f)))
+ """)
+
 
 class BuiltinReversedFunctionTests(BuiltinFunctionTestCase, TranspileTestCase):
  functions = ["reversed"]