1//
2// Copyright (C) 2012 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 SHILL_PROPERTY_ITERATOR_H_
18#define SHILL_PROPERTY_ITERATOR_H_
19
20#include <map>
21#include <string>
22
23#include "shill/accessor_interface.h"
24#include "shill/error.h"
25
26namespace shill {
27
28// An iterator wrapper class to hide the details of what kind of data structure
29// we're using to store key/value pairs for properties. It is intended for use
30// with PropertyStore and always advances to the next readable property.
31template <class V>
32class ReadablePropertyConstIterator {
33 public:
34  ~ReadablePropertyConstIterator() {}
35
36  bool AtEnd() const { return it_ == collection_.end(); }
37
38  void Advance() {
39    if (!AtEnd()) {
40      do {
41        ++it_;
42      } while (MustAdvance());
43    }
44  }
45
46  const std::string& Key() const { return it_->first; }
47
48  const V& value() const { return value_; }
49
50 private:
51  friend class PropertyStore;
52
53  typedef std::shared_ptr<AccessorInterface<V>> VAccessorPtr;
54
55  explicit ReadablePropertyConstIterator(
56      const typename std::map<std::string, VAccessorPtr>& collection)
57      : collection_(collection),
58        it_(collection_.begin()),
59        value_() {
60    if (MustAdvance()) {
61      Advance();
62    }
63  }
64
65  bool MustAdvance() { return !AtEnd() && !RetrieveCurrentValue(); }
66
67  bool RetrieveCurrentValue() {
68    Error error;
69    value_ = it_->second->Get(&error);
70    return error.IsSuccess();
71  }
72
73  const typename std::map<std::string, VAccessorPtr>& collection_;
74  typename std::map<std::string, VAccessorPtr>::const_iterator it_;
75  V value_;
76};
77
78}  // namespace shill
79
80#endif  // SHILL_PROPERTY_ITERATOR_H_
81