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

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

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

@@ -0,0 +1,80 @@
+//
+// 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 <boost/python.hpp>
+#include <boost/python/suite/indexing/vector_indexing_suite.hpp>
+
+#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>;
+
+template <typename Vector>
+struct immer_vector_indexing_suite : boost::python::vector_indexing_suite<
+    Vector, true, immer_vector_indexing_suite<Vector>>
+{
+    using value_t = typename Vector::value_type;
+    using index_t = typename Vector::size_type;
+    using object_t = boost::python::object;
+
+    static void forbidden() { throw std::runtime_error{"immutable!"}; }
+    static void todo() { throw std::runtime_error{"TODO!"}; }
+
+    static const value_t& get_item(const Vector& v, index_t i) { return v[i]; }
+    static object_t get_slice(const Vector&, index_t, index_t) { todo(); }
+
+    static void set_item(const Vector&, index_t, const value_t&) { forbidden(); }
+    static void delete_item(const Vector&, index_t) { forbidden(); }
+    static void set_slice(const Vector&, index_t, index_t, const value_t&) { forbidden(); }
+    static void delete_slice(const Vector&, index_t, index_t) { forbidden(); }
+    template <typename Iter>
+    static void set_slice(const Vector&, index_t, index_t, Iter, Iter) { forbidden(); }
+    template <class Iter>
+    static void extend(const Vector& container, Iter, Iter) { forbidden(); }
+};
+
+} // anonymous namespace
+
+
+BOOST_PYTHON_MODULE(immer_python_module)
+{
+    using namespace boost::python;
+
+    using vector_t = immer::vector<object, memory_t>;
+
+    class_<vector_t>("Vector")
+        .def(immer_vector_indexing_suite<vector_t>())
+        .def("append",
+             +[] (const vector_t& v, object x) {
+                 return v.push_back(std::move(x));
+              })
+        .def("set",
+             +[] (const vector_t& v, std::size_t i, object x) {
+                 return v.set(i, std::move(x));
+              })
+        ;
+}