merge(3p/immer): Subtree merge at 'ad3e3556d' as 'third_party/immer'

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

third_party/immer/extra/python/src/immer-pybind.cpp

@@ -0,0 +1,77 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#include <pybind11/pybind11.h>
+
+#include <immer/vector.hpp>
+#include <immer/refcount/unsafe_refcount_policy.hpp>
+
+namespace {
+
+struct heap_t
+{
+    template <typename ...Tags>
+    static void* allocate(std::size_t size, Tags...)
+    {
+        return PyMem_Malloc(size);
+    }
+
+    template <typename ...Tags>
+    static void deallocate(std::size_t, void* obj, Tags...)
+    {
+        PyMem_Free(obj);
+    }
+};
+
+using memory_t = immer::memory_policy<
+    immer::unsafe_free_list_heap_policy<heap_t>,
+    immer::unsafe_refcount_policy>;
+
+} // anonymous namespace
+
+namespace py = pybind11;
+
+PYBIND11_PLUGIN(immer_python_module)
+{
+    py::module m("immer", R"pbdoc(
+        Immer
+        -----
+        .. currentmodule:: immer
+        .. autosummary::
+           :toctree: _generate
+           Vector
+    )pbdoc");
+
+    using vector_t = immer::vector<py::object, memory_t>;
+
+    py::class_<vector_t>(m, "Vector")
+        .def(py::init<>())
+        .def("__len__", &vector_t::size)
+        .def("__getitem__",
+             [] (const vector_t& v, std::size_t i) {
+                 if (i > v.size())
+                     throw py::index_error{"Index out of range"};
+                 return v[i];
+             })
+        .def("append",
+             [] (const vector_t& v, py::object x) {
+                 return v.push_back(std::move(x));
+             })
+        .def("set",
+             [] (const vector_t& v, std::size_t i, py::object x) {
+                 return v.set(i, std::move(x));
+             });
+
+#ifdef VERSION_INFO
+    m.attr("__version__") = py::str(VERSION_INFO);
+#else
+    m.attr("__version__") = py::str("dev");
+#endif
+
+    return m.ptr();
+}