python: Add access to the property_tree from Python

Example:
>>> usrp = uhd.usrp.multi_usrp("")
>>> tree = usrp.get_tree()
>>> print(tree.access_int("/name").get())

1 files changed, 61 insertions, 0 deletions

diff --git a/host/lib/property_tree_python.cpp b/host/lib/property_tree_python.cpp
new file mode 100644
index 000000000..0b7f18aa2
--- /dev/null
+++ b/host/lib/property_tree_python.cpp
@@ -0,0 +1,61 @@
+//
+// Copyright 2020 Ettus Research, a National Instruments Brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#include "property_tree_python.hpp"
+#include <uhd/property_tree.hpp>
+#include <pybind11/pybind11.h>
+#include <pybind11/stl.h>
+#include <string>
+
+namespace py = pybind11;
+
+template <typename T>
+void export_property(py::module& m, const std::string& type_str)
+{
+    const std::string classname = std::string("property__") + type_str;
+    py::class_<uhd::property<T>>(m, classname.c_str())
+        .def("get", &uhd::property<T>::get)
+        .def("get_desired", &uhd::property<T>::get_desired)
+        .def("set", &uhd::property<T>::set)
+        .def("set_coerced", &uhd::property<T>::set_coerced);
+}
+
+void export_property_tree(py::module& m)
+{
+    using property_tree = uhd::property_tree;
+    using fs_path = uhd::fs_path;
+
+    py::class_<fs_path>(m, "fs_path")
+        // Constructors
+        .def(py::init<>())
+        .def(py::init<std::string>());
+    py::implicitly_convertible<std::string, fs_path>();
+
+    // Per type we want to expose, add one line here, and one accessor below
+    export_property<int>(m, "int");
+    export_property<double>(m, "double");
+    export_property<std::string>(m, "str");
+    export_property<bool>(m, "bool");
+
+    py::class_<property_tree>(m, "property_tree")
+        .def("subtree", &property_tree::subtree, py::arg("path"))
+        .def("exists", &property_tree::exists, py::arg("path"))
+        .def("list", &property_tree::list, py::arg("path"))
+        // One line per type
+        .def(
+            "access_int", &property_tree::access<int>, py::return_value_policy::reference)
+        .def("access_double",
+            &property_tree::access<double>,
+            py::return_value_policy::reference)
+        .def("access_str",
+            &property_tree::access<std::string>,
+            py::return_value_policy::reference)
+        .def("access_bool",
+            &property_tree::access<bool>,
+            py::return_value_policy::reference)
+        // End of types
+        ;
+}