Merge pull request RustPython#3646 from sum12/aiter

implement aiter

Author: youknowone

Lib/test/test_asyncgen.py

@@ -543,8 +543,6 @@ async def consume():
         self.loop.run_until_complete(consume())
         self.assertEqual(results, [1, 2])
 
-    # TODO: RUSTPYTHON, NameError: name 'aiter' is not defined
-    @unittest.expectedFailure
     def test_aiter_idempotent(self):
         async def gen():
             yield 1
@@ -766,8 +764,6 @@ def run_test(test):
         run_test(test5)
         run_test(test6)
 
-    # TODO: RUSTPYTHON, NameError: name 'aiter' is not defined
-    @unittest.expectedFailure
     def test_aiter_bad_args(self):
         async def gen():
             yield 1

vm/src/stdlib/builtins.rs

@@ -12,6 +12,7 @@ mod builtins {
     use crate::compile;
     use crate::{
         builtins::{
+            asyncgenerator::PyAsyncGen,
             enumerate::PyReverseSequenceIterator,
             function::{PyCellRef, PyFunctionRef},
             int::PyIntRef,
@@ -426,6 +427,15 @@ mod builtins {
         }
     }
 
+    #[pyfunction]
+    fn aiter(iter_target: PyObjectRef, vm: &VirtualMachine) -> PyResult {
+        if iter_target.payload_is::<PyAsyncGen>() {
+            vm.call_special_method(iter_target, "__aiter__", ())
+        } else {
+            Err(vm.new_type_error("wrong argument type".to_owned()))
+        }
+    }
+
     #[pyfunction]
     fn len(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult<usize> {
         obj.length(vm)