From 2c9124bbbe736881fa8f9f33ea7817c98b43bf8b Mon Sep 17 00:00:00 2001
From: Wenzel Jakob <wenzel.jakob@epfl.ch>
Date: Sat, 3 Jun 2023 15:42:22 +0200
Subject: [PATCH] ignore duplicate bind_vector/bind_map declarations

---
 docs/api_extra.rst                 | 6 ++++++
 include/nanobind/stl/bind_map.h    | 6 ++++++
 include/nanobind/stl/bind_vector.h | 6 ++++++
 tests/test_stl_bind_vector.cpp     | 3 +++
 4 files changed, 21 insertions(+)

diff --git a/docs/api_extra.rst b/docs/api_extra.rst
index dd2da657..29aee3dd 100644
--- a/docs/api_extra.rst
+++ b/docs/api_extra.rst
@@ -243,6 +243,9 @@ include directive:
    not comparable or copy-assignable, some of these functions will not be
    generated.
 
+   The binding operation is a no-op if the vector type has already been
+   registered with nanobind.
+
 .. _map_bindings:
 
 STL map bindings
@@ -308,6 +311,9 @@ nanobind API and require an additional include directive:
       * - ``items(self, arg: Map) -> Map.ItemView``
         - Returns an iterable view of the map's items
 
+   The binding operation is a no-op if the map type has already been
+   registered with nanobind.
+
 Unique pointer deleter
 ----------------------
 
diff --git a/include/nanobind/stl/bind_map.h b/include/nanobind/stl/bind_map.h
index 9cd2de03..b598bd3a 100644
--- a/include/nanobind/stl/bind_map.h
+++ b/include/nanobind/stl/bind_map.h
@@ -42,6 +42,12 @@ class_<Map> bind_map(handle scope, const char *name, Args &&...args) {
     using Key = typename Map::key_type;
     using Value = typename Map::mapped_type;
 
+    handle cl_cur = type<Map>();
+    if (cl_cur.is_valid()) {
+        // Binding already exists, don't re-create
+        return borrow<class_<Map>>(cl_cur);
+    }
+
     auto cl = class_<Map>(scope, name, std::forward<Args>(args)...)
         .def(init<>(),
              "Default constructor")
diff --git a/include/nanobind/stl/bind_vector.h b/include/nanobind/stl/bind_vector.h
index d720c734..e7088120 100644
--- a/include/nanobind/stl/bind_vector.h
+++ b/include/nanobind/stl/bind_vector.h
@@ -48,6 +48,12 @@ class_<Vector> bind_vector(handle scope, const char *name, Args &&...args) {
     using ValueRef = typename detail::iterator_access<typename Vector::iterator>::result_type;
     using Value = std::decay_t<ValueRef>;
 
+    handle cl_cur = type<Vector>();
+    if (cl_cur.is_valid()) {
+        // Binding already exists, don't re-create
+        return borrow<class_<Vector>>(cl_cur);
+    }
+
     auto cl = class_<Vector>(scope, name, std::forward<Args>(args)...)
         .def(init<>(), "Default constructor")
 
diff --git a/tests/test_stl_bind_vector.cpp b/tests/test_stl_bind_vector.cpp
index 3ca76bad..98b6c052 100644
--- a/tests/test_stl_bind_vector.cpp
+++ b/tests/test_stl_bind_vector.cpp
@@ -8,6 +8,9 @@ NB_MODULE(test_bind_vector_ext, m) {
     nb::bind_vector<std::vector<unsigned int>>(m, "VectorInt");
     nb::bind_vector<std::vector<bool>>(m, "VectorBool");
 
+    // Ensure that a repeated binding call is ignored
+    nb::bind_vector<std::vector<bool>>(m, "VectorBool");
+
     struct El {
         explicit El(int v) : a(v) {}
         int a;