From 4103e4dfbce8b6d9579565ab64868a721b01d2a1 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Sun, 11 Sep 2016 22:02:28 -0700 Subject: Issue #28071: Add early-out for differencing from an empty set. --- Misc/NEWS | 2 ++ Objects/setobject.c | 8 ++++++++ 2 files changed, 10 insertions(+) diff --git a/Misc/NEWS b/Misc/NEWS index 1c253b6..083b33f 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -33,6 +33,8 @@ Core and Builtins - Issue #28046: Remove platform-specific directories from sys.path. +- Issue #28071: Add early-out for differencing from an empty set. + - Issue #25758: Prevents zipimport from unnecessarily encoding a filename (patch by Eryk Sun) diff --git a/Objects/setobject.c b/Objects/setobject.c index 6dd403f..5846045 100644 --- a/Objects/setobject.c +++ b/Objects/setobject.c @@ -1476,6 +1476,10 @@ PyDoc_STRVAR(isdisjoint_doc, static int set_difference_update_internal(PySetObject *so, PyObject *other) { + if (PySet_GET_SIZE(so) == 0) { + return 0; + } + if ((PyObject *)so == other) return set_clear_internal(so); @@ -1550,6 +1554,10 @@ set_difference(PySetObject *so, PyObject *other) Py_ssize_t pos = 0; int rv; + if (PySet_GET_SIZE(so) == 0) { + return set_copy(so); + } + if (!PyAnySet_Check(other) && !PyDict_CheckExact(other)) { return set_copy_and_difference(so, other); } -- cgit v0.12