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      1 // Copyright 2015 The Android Open Source Project
      2 //
      3 // Licensed under the Apache License, Version 2.0 (the "License");
      4 // you may not use this file except in compliance with the License.
      5 // You may obtain a copy of the License at
      6 //
      7 //      http://www.apache.org/licenses/LICENSE-2.0
      8 //
      9 // Unless required by applicable law or agreed to in writing, software
     10 // distributed under the License is distributed on an "AS IS" BASIS,
     11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 // See the License for the specific language governing permissions and
     13 // limitations under the License.
     14 
     15 #ifndef BRILLO_VALUE_CONVERSION_H_
     16 #define BRILLO_VALUE_CONVERSION_H_
     17 
     18 // This file provides a set of helper functions to convert between base::Value
     19 // and native types. Apart from handling standard types such as 'int' and
     20 // 'std::string' it also provides conversion to/from std::vector<T> (which
     21 // converts to Base::listValue) and std::map<std::string, T> (convertible to
     22 // base::DictionaryValue).
     23 
     24 #include <map>
     25 #include <memory>
     26 #include <string>
     27 #include <vector>
     28 
     29 #include <base/values.h>
     30 #include <brillo/brillo_export.h>
     31 
     32 namespace brillo {
     33 
     34 inline bool FromValue(const base::Value& in_value, bool* out_value) {
     35   return in_value.GetAsBoolean(out_value);
     36 }
     37 
     38 inline bool FromValue(const base::Value& in_value, int* out_value) {
     39   return in_value.GetAsInteger(out_value);
     40 }
     41 
     42 inline bool FromValue(const base::Value& in_value, double* out_value) {
     43   return in_value.GetAsDouble(out_value);
     44 }
     45 
     46 inline bool FromValue(const base::Value& in_value, std::string* out_value) {
     47   return in_value.GetAsString(out_value);
     48 }
     49 
     50 inline bool FromValue(const base::Value& in_value,
     51                       const base::ListValue** out_value) {
     52   return in_value.GetAsList(out_value);
     53 }
     54 
     55 inline bool FromValue(const base::Value& in_value,
     56                       const base::DictionaryValue** out_value) {
     57   return in_value.GetAsDictionary(out_value);
     58 }
     59 
     60 BRILLO_EXPORT bool FromValue(const base::Value& in_value,
     61                              std::unique_ptr<base::ListValue>* out_value);
     62 BRILLO_EXPORT bool FromValue(const base::Value& in_value,
     63                              std::unique_ptr<base::DictionaryValue>* out_value);
     64 
     65 template <typename T, typename Pred, typename Alloc>
     66 bool FromValue(const base::Value& in_value,
     67               std::map<std::string, T, Pred, Alloc>* out_value);
     68 
     69 template <typename T, typename Alloc>
     70 bool FromValue(const base::Value& in_value, std::vector<T, Alloc>* out_value) {
     71   const base::ListValue* list = nullptr;
     72   if (!in_value.GetAsList(&list))
     73     return false;
     74   out_value->clear();
     75   out_value->reserve(list->GetSize());
     76   for (const auto& item : *list) {
     77     T value{};
     78     if (!FromValue(*item, &value))
     79       return false;
     80     out_value->push_back(std::move(value));
     81   }
     82   return true;
     83 }
     84 
     85 template <typename T, typename Pred, typename Alloc>
     86 bool FromValue(const base::Value& in_value,
     87               std::map<std::string, T, Pred, Alloc>* out_value) {
     88   const base::DictionaryValue* dict = nullptr;
     89   if (!in_value.GetAsDictionary(&dict))
     90     return false;
     91   out_value->clear();
     92   for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd(); it.Advance()) {
     93     if (!FromValue(it.value(), &(*out_value)[it.key()]))
     94       return false;
     95   }
     96   return true;
     97 }
     98 
     99 template <typename T>
    100 T FromValue(const base::Value& value) {
    101   T out_value{};
    102   CHECK(FromValue(value, &out_value));
    103   return out_value;
    104 }
    105 
    106 BRILLO_EXPORT std::unique_ptr<base::Value> ToValue(int value);
    107 BRILLO_EXPORT std::unique_ptr<base::Value> ToValue(bool value);
    108 BRILLO_EXPORT std::unique_ptr<base::Value> ToValue(double value);
    109 BRILLO_EXPORT std::unique_ptr<base::Value> ToValue(const std::string& value);
    110 // Implicit conversion of char* to 'bool' has precedence over the user-defined
    111 // std::string conversion. Override this behavior explicitly.
    112 BRILLO_EXPORT std::unique_ptr<base::Value> ToValue(const char* value);
    113 
    114 template <typename T, typename Pred, typename Alloc>
    115 std::unique_ptr<base::Value> ToValue(
    116     const std::map<std::string, T, Pred, Alloc>& dictionary);
    117 
    118 template <typename T, typename Alloc>
    119 std::unique_ptr<base::Value> ToValue(const std::vector<T, Alloc>& list) {
    120   std::unique_ptr<base::ListValue> result{new base::ListValue};
    121   for (const auto& value : list)
    122     result->Append(ToValue(value));
    123   return std::move(result);
    124 }
    125 
    126 template <typename T, typename Pred, typename Alloc>
    127 std::unique_ptr<base::Value> ToValue(
    128     const std::map<std::string, T, Pred, Alloc>& dictionary) {
    129   std::unique_ptr<base::DictionaryValue> result{new base::DictionaryValue};
    130   for (const auto& pair : dictionary)
    131     result->Set(pair.first, ToValue(pair.second));
    132   return std::move(result);
    133 }
    134 
    135 }  // namespace brillo
    136 
    137 #endif  // BRILLO_VALUE_CONVERSION_H_
    138