Add negative indexing support to stl_bind. (#1882)
diff --git a/include/pybind11/stl_bind.h b/include/pybind11/stl_bind.h
index 1f87252..d3adaed 100644
--- a/include/pybind11/stl_bind.h
+++ b/include/pybind11/stl_bind.h
@@ -115,6 +115,14 @@
using SizeType = typename Vector::size_type;
using DiffType = typename Vector::difference_type;
+ auto wrap_i = [](DiffType i, SizeType n) {
+ if (i < 0)
+ i += n;
+ if (i < 0 || (SizeType)i >= n)
+ throw index_error();
+ return i;
+ };
+
cl.def("append",
[](Vector &v, const T &value) { v.push_back(value); },
arg("x"),
@@ -159,10 +167,13 @@
);
cl.def("insert",
- [](Vector &v, SizeType i, const T &x) {
- if (i > v.size())
+ [](Vector &v, DiffType i, const T &x) {
+ // Can't use wrap_i; i == v.size() is OK
+ if (i < 0)
+ i += v.size();
+ if (i < 0 || (SizeType)i > v.size())
throw index_error();
- v.insert(v.begin() + (DiffType) i, x);
+ v.insert(v.begin() + i, x);
},
arg("i") , arg("x"),
"Insert an item at a given position."
@@ -180,11 +191,10 @@
);
cl.def("pop",
- [](Vector &v, SizeType i) {
- if (i >= v.size())
- throw index_error();
- T t = v[i];
- v.erase(v.begin() + (DiffType) i);
+ [wrap_i](Vector &v, DiffType i) {
+ i = wrap_i(i, v.size());
+ T t = v[(SizeType) i];
+ v.erase(v.begin() + i);
return t;
},
arg("i"),
@@ -192,10 +202,9 @@
);
cl.def("__setitem__",
- [](Vector &v, SizeType i, const T &t) {
- if (i >= v.size())
- throw index_error();
- v[i] = t;
+ [wrap_i](Vector &v, DiffType i, const T &t) {
+ i = wrap_i(i, v.size());
+ v[(SizeType)i] = t;
}
);
@@ -238,10 +247,9 @@
);
cl.def("__delitem__",
- [](Vector &v, SizeType i) {
- if (i >= v.size())
- throw index_error();
- v.erase(v.begin() + DiffType(i));
+ [wrap_i](Vector &v, DiffType i) {
+ i = wrap_i(i, v.size());
+ v.erase(v.begin() + i);
},
"Delete the list elements at index ``i``"
);
@@ -277,13 +285,21 @@
void vector_accessor(enable_if_t<!vector_needs_copy<Vector>::value, Class_> &cl) {
using T = typename Vector::value_type;
using SizeType = typename Vector::size_type;
+ using DiffType = typename Vector::difference_type;
using ItType = typename Vector::iterator;
+ auto wrap_i = [](DiffType i, SizeType n) {
+ if (i < 0)
+ i += n;
+ if (i < 0 || (SizeType)i >= n)
+ throw index_error();
+ return i;
+ };
+
cl.def("__getitem__",
- [](Vector &v, SizeType i) -> T & {
- if (i >= v.size())
- throw index_error();
- return v[i];
+ [wrap_i](Vector &v, DiffType i) -> T & {
+ i = wrap_i(i, v.size());
+ return v[(SizeType)i];
},
return_value_policy::reference_internal // ref + keepalive
);
@@ -303,12 +319,15 @@
void vector_accessor(enable_if_t<vector_needs_copy<Vector>::value, Class_> &cl) {
using T = typename Vector::value_type;
using SizeType = typename Vector::size_type;
+ using DiffType = typename Vector::difference_type;
using ItType = typename Vector::iterator;
cl.def("__getitem__",
- [](const Vector &v, SizeType i) -> T {
- if (i >= v.size())
+ [](const Vector &v, DiffType i) -> T {
+ if (i < 0 && (i += v.size()) < 0)
throw index_error();
- return v[i];
+ if ((SizeType)i >= v.size())
+ throw index_error();
+ return v[(SizeType)i];
}
);
diff --git a/tests/test_stl_binders.py b/tests/test_stl_binders.py
index 52c8ac0..6d5a159 100644
--- a/tests/test_stl_binders.py
+++ b/tests/test_stl_binders.py
@@ -53,6 +53,16 @@
v_int2.extend(x for x in range(5))
assert v_int2 == m.VectorInt([0, 99, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4])
+ # test negative indexing
+ assert v_int2[-1] == 4
+
+ # insert with negative index
+ v_int2.insert(-1, 88)
+ assert v_int2 == m.VectorInt([0, 99, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 88, 4])
+
+ # delete negative index
+ del v_int2[-1]
+ assert v_int2 == m.VectorInt([0, 99, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 88])
# related to the PyPy's buffer protocol.
@pytest.unsupported_on_pypy