1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef NETUTILS_MISC_H
18#define NETUTILS_MISC_H
19
20#include <map>
21
22namespace android {
23namespace netdutils {
24
25// Lookup key in map, returing a default value if key is not found
26template <typename U, typename V>
27inline const V& findWithDefault(const std::map<U, V>& map, const U& key, const V& dflt) {
28    auto it = map.find(key);
29    return (it == map.end()) ? dflt : it->second;
30}
31
32// Movable, copiable, scoped lambda (or std::function) runner. Useful
33// for running arbitrary cleanup or logging code when exiting a scope.
34//
35// Compare to defer in golang.
36template <typename FnT>
37class Cleanup {
38  public:
39    Cleanup() = delete;
40    Cleanup(FnT fn) : mFn(fn) {}
41    ~Cleanup() { mFn(); }
42
43    void release() { mFn = {}; }
44
45  private:
46    FnT mFn;
47};
48
49// Helper to make a new Cleanup. Avoids complex or impossible syntax
50// when wrapping lambdas.
51//
52// Usage:
53// auto cleanup = makeCleanup([](){ your_code_here; });
54template <typename FnT>
55Cleanup<FnT> makeCleanup(FnT fn) {
56    return Cleanup<FnT>(fn);
57}
58
59}  // namespace netdutils
60}  // namespace android
61
62#endif /* NETUTILS_MISC_H */
63