diff --git a/include/pybind11/stl_bind.h b/include/pybind11/stl_bind.h index 82317b379..050be83cc 100644 --- a/include/pybind11/stl_bind.h +++ b/include/pybind11/stl_bind.h @@ -595,6 +595,23 @@ template auto map_if_insertion_operator(Class_ & ); } +template +struct keys_view +{ + Map ↦ +}; + +template +struct values_view +{ + Map ↦ +}; + +template +struct items_view +{ + Map ↦ +}; PYBIND11_NAMESPACE_END(detail) @@ -602,6 +619,9 @@ template , typename... class_ bind_map(handle scope, const std::string &name, Args&&... args) { using KeyType = typename Map::key_type; using MappedType = typename Map::mapped_type; + using KeysView = detail::keys_view; + using ValuesView = detail::values_view; + using ItemsView = detail::items_view; using Class_ = class_; // If either type is a non-module-local bound type then make the map binding non-local as well; @@ -615,6 +635,12 @@ class_ bind_map(handle scope, const std::string &name, Args&&. } Class_ cl(scope, name.c_str(), pybind11::module_local(local), std::forward(args)...); + class_ keys_view( + scope, ("KeysView[" + name + "]").c_str(), pybind11::module_local(local)); + class_ values_view( + scope, ("ValuesView[" + name + "]").c_str(), pybind11::module_local(local)); + class_ items_view( + scope, ("ItemsView[" + name + "]").c_str(), pybind11::module_local(local)); cl.def(init<>()); @@ -628,12 +654,22 @@ class_ bind_map(handle scope, const std::string &name, Args&&. cl.def("__iter__", [](Map &m) { return make_key_iterator(m.begin(), m.end()); }, - keep_alive<0, 1>() /* Essential: keep list alive while iterator exists */ + keep_alive<0, 1>() /* Essential: keep map alive while iterator exists */ + ); + + cl.def("keys", + [](Map &m) { return KeysView{m}; }, + keep_alive<0, 1>() /* Essential: keep map alive while view exists */ + ); + + cl.def("values", + [](Map &m) { return ValuesView{m}; }, + keep_alive<0, 1>() /* Essential: keep map alive while view exists */ ); cl.def("items", - [](Map &m) { return make_iterator(m.begin(), m.end()); }, - keep_alive<0, 1>() /* Essential: keep list alive while iterator exists */ + [](Map &m) { return ItemsView{m}; }, + keep_alive<0, 1>() /* Essential: keep map alive while view exists */ ); cl.def("__getitem__", @@ -654,6 +690,8 @@ class_ bind_map(handle scope, const std::string &name, Args&&. return true; } ); + // Fallback for when the object is not of the key type + cl.def("__contains__", [](Map &, const object &) -> bool { return false; }); // Assignment provided only if the type is copyable detail::map_assignment(cl); @@ -669,6 +707,40 @@ class_ bind_map(handle scope, const std::string &name, Args&&. cl.def("__len__", &Map::size); + keys_view.def("__len__", [](KeysView &view) { return view.map.size(); }); + keys_view.def("__iter__", + [](KeysView &view) { + return make_key_iterator(view.map.begin(), view.map.end()); + }, + keep_alive<0, 1>() /* Essential: keep view alive while iterator exists */ + ); + keys_view.def("__contains__", + [](KeysView &view, const KeyType &k) -> bool { + auto it = view.map.find(k); + if (it == view.map.end()) + return false; + return true; + } + ); + // Fallback for when the object is not of the key type + keys_view.def("__contains__", [](KeysView &, const object &) -> bool { return false; }); + + values_view.def("__len__", [](ValuesView &view) { return view.map.size(); }); + values_view.def("__iter__", + [](ValuesView &view) { + return make_value_iterator(view.map.begin(), view.map.end()); + }, + keep_alive<0, 1>() /* Essential: keep view alive while iterator exists */ + ); + + items_view.def("__len__", [](ItemsView &view) { return view.map.size(); }); + items_view.def("__iter__", + [](ItemsView &view) { + return make_iterator(view.map.begin(), view.map.end()); + }, + keep_alive<0, 1>() /* Essential: keep view alive while iterator exists */ + ); + return cl; } diff --git a/tests/test_stl_binders.py b/tests/test_stl_binders.py index 475a9ec40..a68dcd31d 100644 --- a/tests/test_stl_binders.py +++ b/tests/test_stl_binders.py @@ -160,15 +160,43 @@ def test_map_string_double(): mm["b"] = 2.5 assert list(mm) == ["a", "b"] - assert list(mm.items()) == [("a", 1), ("b", 2.5)] assert str(mm) == "MapStringDouble{a: 1, b: 2.5}" + assert "b" in mm + assert "c" not in mm + assert 123 not in mm + + # Check that keys, values, items are views, not merely iterable + keys = mm.keys() + values = mm.values() + items = mm.items() + assert list(keys) == ["a", "b"] + assert len(keys) == 2 + assert "a" in keys + assert "c" not in keys + assert 123 not in keys + assert list(items) == [("a", 1), ("b", 2.5)] + assert len(items) == 2 + assert ("b", 2.5) in items + assert "hello" not in items + assert ("b", 2.5, None) not in items + assert list(values) == [1, 2.5] + assert len(values) == 2 + assert 1 in values + assert 2 not in values + # Check that views update when the map is updated + mm["c"] = -1 + assert list(keys) == ["a", "b", "c"] + assert list(values) == [1, 2.5, -1] + assert list(items) == [("a", 1), ("b", 2.5), ("c", -1)] um = m.UnorderedMapStringDouble() um["ua"] = 1.1 um["ub"] = 2.6 assert sorted(list(um)) == ["ua", "ub"] + assert list(um.keys()) == list(um) assert sorted(list(um.items())) == [("ua", 1.1), ("ub", 2.6)] + assert list(zip(um.keys(), um.values())) == list(um.items()) assert "UnorderedMapStringDouble" in str(um)