Merge pull request RustPython#473 from janczer/add_list_copy

Add copy method to set object

Author: windelbouwman

tests/snippets/set.py

@@ -77,5 +77,12 @@ def __hash__(self):
 a = set([1, 2, 3])
 assert a.discard(1) is None
 assert not 1 in a
-
 assert a.discard(42) is None
+
+a = set([1,2,3])
+b = a.copy()
+assert len(a) == 3
+assert len(b) == 3
+b.clear()
+assert len(a) == 3
+assert len(b) == 0

vm/src/obj/objset.rs

@@ -178,6 +178,16 @@ fn set_len(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.context().new_int(elements.len()))
 }
 
+fn set_copy(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    trace!("set.copy called with: {:?}", args);
+    arg_check!(vm, args, required = [(s, Some(vm.ctx.set_type()))]);
+    let elements = get_elements(s);
+    Ok(PyObject::new(
+        PyObjectPayload::Set { elements },
+        vm.ctx.set_type(),
+    ))
+}
+
 fn set_repr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(o, Some(vm.ctx.set_type()))]);
 
@@ -477,6 +487,7 @@ pub fn init(context: &PyContext) {
     context.set_attr(&set_type, "remove", context.new_rustfunc(set_remove));
     context.set_attr(&set_type, "discard", context.new_rustfunc(set_discard));
     context.set_attr(&set_type, "clear", context.new_rustfunc(set_clear));
+    context.set_attr(&set_type, "copy", context.new_rustfunc(set_copy));
 
     let frozenset_type = &context.frozenset_type;