cxx: New package

Start new package that provides C++ amendments to be used by libgolang
and its users. Current functionality: dict and set that wrap
std::unordered_map and std::unordered_set into ergonomic interface.

The code originates from wendelin.core:
https://lab.nexedi.com/kirr/wendelin.core/blob/5a045ed1/wcfs/internal/wcfs_misc.h#L214-257

Pyx/nogil only.

MANIFEST.in

 include COPYING README.rst CHANGELOG.rst tox.ini pyproject.toml trun
 include golang/libgolang.h
 include golang/runtime/libgolang.cpp
+include golang/cxx.h
 include golang/errors.h
 include golang/errors.cpp
 include golang/sync.h

golang/cxx.h

+#ifndef _NXD_LIBGOLANG_CXX_H
+#define _NXD_LIBGOLANG_CXX_H
+
+// Copyright (C) 2019  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+// Package cxx provides C++ amendments to be used by libgolang and its users.
+
+#include <unordered_map>
+#include <unordered_set>
+#include <tuple>
+
+// golang::cxx::
+namespace golang {
+namespace cxx {
+
+using std::tuple;
+
+// dict wraps unordered_map into ergonomic interface.
+template<typename Key, typename Value>
+struct dict : std::unordered_map<Key, Value> {
+    // has returns whether dict has element k.
+    bool has(const Key &k) const {
+        const dict &d = *this;
+        return d.find(k) != d.end();
+    }
+
+    // get implements `d[k] -> (v, ok)`.
+    tuple<Value, bool> get(const Key &k) const {
+        const dict &d = *this;
+        auto _ = d.find(k);
+        if (_ == d.end())
+            return make_tuple(Value(), false);
+        return make_tuple(_->second, true);
+    }
+
+    // pop implements `d[k] -> (v, ok); del d[k]`.
+    tuple<Value, bool> pop(const Key &k) {
+        dict &d = *this;
+        auto _ = d.find(k);
+        if (_ == d.end())
+            return make_tuple(Value(), false);
+        Value v = _->second;
+        d.erase(_);
+        return make_tuple(v, true);
+    }
+};
+
+// set wraps unordered_set into ergonomic interface.
+template<typename Key>
+struct set : std::unordered_set<Key> {
+    // has returns whether set has element k.
+    bool has(const Key &k) const {
+        const set &s = *this;
+        return s.find(k) != s.end();
+    }
+};
+
+
+}}  // golang::cxx::
+
+
+#endif  // _NXD_LIBGOLANG_CXX_H

golang/cxx.pxd

+# cython: language_level=2
+# Copyright (C) 2019  Nexedi SA and Contributors.
+#                     Kirill Smelkov <kirr@nexedi.com>
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Free Software licenses or any of the Open Source
+# Initiative approved licenses and Convey the resulting work. Corresponding
+# source of such a combination shall include the source code for all other
+# software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.
+# See https://www.nexedi.com/licensing for rationale and options.
+"""Package cxx provides C++ amendments to be used by libgolang and its users."""
+
+cimport libcpp.unordered_map
+cimport libcpp.unordered_set
+
+cdef extern from "<golang/cxx.h>" namespace "golang::cxx" nogil:
+    cppclass dict[Key, Value] (libcpp.unordered_map.unordered_map[Key, Value]):
+        bint has(Key k) const
+        # TODO get
+        # TODO pop
+
+    cppclass set[Key] (libcpp.unordered_set.unordered_set[Key]):
+        bint has(Key k) const

golang/pyx/build.py

@@ -166,6 +166,8 @@ def Extension(name, sources, **kw):
     dependv.append('%s/golang/libgolang.h'  % pygo)
     dependv.append('%s/golang/_golang.pxd'  % pygo)
     dependv.append('%s/golang/__init__.pxd' % pygo)
+    dependv.append('%s/golang/cxx.h'        % pygo)
+    dependv.append('%s/golang/cxx.pxd'      % pygo)
     dependv.append('%s/golang/errors.h'     % pygo)
     dependv.append('%s/golang/errors.pxd'   % pygo)
     dependv.append('%s/golang/_errors.pxd'  % pygo)

setup.py

@@ -198,6 +198,7 @@ setup(
                          'golang/time.cpp'],
                         depends = [
                             'golang/libgolang.h',
+                            'golang/cxx.h',
                             'golang/errors.h',
                             'golang/sync.h',
                             'golang/time.h'],