Add support for bool (#382)

* Add bool_ support

* Directly compare against Py_True

docs/api_core.rst

@@ -892,6 +892,24 @@ Wrapper classes
       Return the pointer wrapped by the capsule.
 
 
+.. cpp:class:: bool_: public object
+
+   This wrapper class represents Python ``bool`` instances.
+
+   .. cpp:function:: int_(handle h)
+
+      Performs a boolean cast within Python. This is equivalent to the Python
+      expression ``bool(h)``.
+
+   .. cpp:function:: explicit bool_(bool value)
+
+      Convert an C++ boolean instance into a Python ``bool``.
+
+   .. cpp:function:: explicit operator bool() const
+
+      Extract the boolean value underlying this object.
+
+
 .. cpp:class:: int_: public object
 
    This wrapper class represents Python ``int`` instances. It can handle large

docs/exchanging.rst

@@ -384,7 +384,7 @@ directives:
 :cpp:class:`bytes`, :cpp:class:`callable`, :cpp:class:`capsule`,
 :cpp:class:`dict`, :cpp:class:`ellipsis`, :cpp:class:`handle`,
 :cpp:class:`handle_t\<T\> <handle_t>`,
-:cpp:class:`int_`, :cpp:class:`float_`,
+:cpp:class:`bool_`, :cpp:class:`int_`, :cpp:class:`float_`,
 :cpp:class:`iterable`,
 :cpp:class:`iterator`, :cpp:class:`list`, :cpp:class:`mapping`,
 :cpp:class:`module_`, :cpp:class:`object`, :cpp:class:`set`, :cpp:class:`sequence`,

include/nanobind/nb_lib.h

@@ -133,6 +133,9 @@ NB_CORE PyObject *bytes_from_cstr_and_size(const char *c, size_t n);
 
 // ========================================================================
 
+/// Convert a Python object into a Python boolean object
+NB_CORE PyObject *bool_from_obj(PyObject *o);
+
 /// Convert a Python object into a Python integer object
 NB_CORE PyObject *int_from_obj(PyObject *o);
 

include/nanobind/nb_types.h

@@ -340,6 +340,20 @@ class capsule : public object {
     void *data() const { return PyCapsule_GetPointer(m_ptr, name()); }
 };
 
+class bool_ : public object {
+    NB_OBJECT_DEFAULT(bool_, object, "bool", PyBool_Check)
+
+    explicit bool_(handle h)
+        : object(detail::bool_from_obj(h.ptr()), detail::borrow_t{}) { }
+
+    explicit bool_(bool value)
+        : object(value ? Py_True : Py_False, detail::borrow_t{}) { }
+
+    explicit operator bool() const {
+        return m_ptr == Py_True;
+    }
+};
+
 class int_ : public object {
     NB_OBJECT_DEFAULT(int_, object, "int", PyLong_Check)
 

src/common.cpp

@@ -566,6 +566,13 @@ PyObject *bytes_from_cstr_and_size(const char *str, size_t size) {
 
 // ========================================================================
 
+PyObject *bool_from_obj(PyObject *o) {
+    int rv = PyObject_IsTrue(o);
+    if (rv == -1)
+        raise_python_error();
+    return rv == 1 ? Py_True : Py_False;
+}
+
 PyObject *int_from_obj(PyObject *o) {
     PyObject *result = PyNumber_Long(o);
     if (!result)