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       1                 :            : // Copyright (c) 2019-2022 The Bitcoin Core developers
       2                 :            : // Distributed under the MIT software license, see the accompanying
       3                 :            : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :            : 
       5                 :            : #ifndef BITCOIN_COMMON_SETTINGS_H
       6                 :            : #define BITCOIN_COMMON_SETTINGS_H
       7                 :            : 
       8                 :            : #include <util/fs.h>
       9                 :            : 
      10                 :            : #include <cstddef>
      11                 :            : #include <map>
      12                 :            : #include <string>
      13                 :            : #include <vector>
      14                 :            : 
      15                 :            : class UniValue;
      16                 :            : 
      17                 :            : namespace common {
      18                 :            : 
      19                 :            : //! Settings value type (string/integer/boolean/null variant).
      20                 :            : //!
      21                 :            : //! @note UniValue is used here for convenience and because it can be easily
      22                 :            : //!       serialized in a readable format. But any other variant type that can
      23                 :            : //!       be assigned strings, int64_t, and bool values and has get_str(),
      24                 :            : //!       getInt<int64_t>(), get_bool(), isNum(), isBool(), isFalse(), isTrue() and
      25                 :            : //!       isNull() methods can be substituted if there's a need to move away
      26                 :            : //!       from UniValue. (An implementation with boost::variant was posted at
      27                 :            : //!       https://github.com/bitcoin/bitcoin/pull/15934/files#r337691812)
      28                 :            : using SettingsValue = UniValue;
      29                 :            : 
      30                 :            : //! Stored settings. This struct combines settings from the command line, a
      31                 :            : //! read-only configuration file, and a read-write runtime settings file.
      32                 :          0 : struct Settings {
      33                 :            :     //! Map of setting name to forced setting value.
      34                 :            :     std::map<std::string, SettingsValue> forced_settings;
      35                 :            :     //! Map of setting name to list of command line values.
      36                 :            :     std::map<std::string, std::vector<SettingsValue>> command_line_options;
      37                 :            :     //! Map of setting name to read-write file setting value.
      38                 :            :     std::map<std::string, SettingsValue> rw_settings;
      39                 :            :     //! Map of config section name and setting name to list of config file values.
      40                 :            :     std::map<std::string, std::map<std::string, std::vector<SettingsValue>>> ro_config;
      41                 :            : };
      42                 :            : 
      43                 :            : //! Read settings file.
      44                 :            : bool ReadSettings(const fs::path& path,
      45                 :            :     std::map<std::string, SettingsValue>& values,
      46                 :            :     std::vector<std::string>& errors);
      47                 :            : 
      48                 :            : //! Write settings file.
      49                 :            : bool WriteSettings(const fs::path& path,
      50                 :            :     const std::map<std::string, SettingsValue>& values,
      51                 :            :     std::vector<std::string>& errors);
      52                 :            : 
      53                 :            : //! Get settings value from combined sources: forced settings, command line
      54                 :            : //! arguments, runtime read-write settings, and the read-only config file.
      55                 :            : //!
      56                 :            : //! @param ignore_default_section_config - ignore values in the default section
      57                 :            : //!                                        of the config file (part before any
      58                 :            : //!                                        [section] keywords)
      59                 :            : //! @param ignore_nonpersistent - ignore non-persistent settings values (forced
      60                 :            : //!                               settings values and values specified on the
      61                 :            : //!                               command line). Only return settings in the
      62                 :            : //!                               read-only config and read-write settings
      63                 :            : //!                               files.
      64                 :            : //! @param get_chain_type - enable special backwards compatible behavior
      65                 :            : //!                         for GetChainType
      66                 :            : SettingsValue GetSetting(const Settings& settings,
      67                 :            :     const std::string& section,
      68                 :            :     const std::string& name,
      69                 :            :     bool ignore_default_section_config,
      70                 :            :     bool ignore_nonpersistent,
      71                 :            :     bool get_chain_type);
      72                 :            : 
      73                 :            : //! Get combined setting value similar to GetSetting(), except if setting was
      74                 :            : //! specified multiple times, return a list of all the values specified.
      75                 :            : std::vector<SettingsValue> GetSettingsList(const Settings& settings,
      76                 :            :     const std::string& section,
      77                 :            :     const std::string& name,
      78                 :            :     bool ignore_default_section_config);
      79                 :            : 
      80                 :            : //! Return true if a setting is set in the default config file section, and not
      81                 :            : //! overridden by a higher priority command-line or network section value.
      82                 :            : //!
      83                 :            : //! This is used to provide user warnings about values that might be getting
      84                 :            : //! ignored unintentionally.
      85                 :            : bool OnlyHasDefaultSectionSetting(const Settings& settings, const std::string& section, const std::string& name);
      86                 :            : 
      87                 :            : //! Accessor for list of settings that skips negated values when iterated over.
      88                 :            : //! The last boolean `false` value in the list and all earlier values are
      89                 :            : //! considered negated.
      90                 :            : struct SettingsSpan {
      91                 :            :     explicit SettingsSpan() = default;
      92                 :         11 :     explicit SettingsSpan(const SettingsValue& value) noexcept : SettingsSpan(&value, 1) {}
      93                 :         23 :     explicit SettingsSpan(const SettingsValue* data, size_t size) noexcept : data(data), size(size) {}
      94                 :            :     explicit SettingsSpan(const std::vector<SettingsValue>& vec) noexcept;
      95                 :            :     const SettingsValue* begin() const; //!< Pointer to first non-negated value.
      96                 :            :     const SettingsValue* end() const;   //!< Pointer to end of values.
      97                 :            :     bool empty() const;                 //!< True if there are any non-negated values.
      98                 :            :     bool last_negated() const;          //!< True if the last value is negated.
      99                 :            :     size_t negated() const;             //!< Number of negated values.
     100                 :            : 
     101                 :            :     const SettingsValue* data = nullptr;
     102                 :            :     size_t size = 0;
     103                 :            : };
     104                 :            : 
     105                 :            : //! Map lookup helper.
     106                 :            : template <typename Map, typename Key>
     107                 :       4781 : auto FindKey(Map&& map, Key&& key) -> decltype(&map.at(key))
     108                 :            : {
     109 [ +  - ][ -  + ]:       4781 :     auto it = map.find(key);
     110 [ +  - ][ +  + ]:       4781 :     return it == map.end() ? nullptr : &it->second;
         [ +  - ][ +  - ]
     111                 :          0 : }
     112                 :            : 
     113                 :            : } // namespace common
     114                 :            : 
     115                 :            : #endif // BITCOIN_COMMON_SETTINGS_H