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KeywordMap

class KeywordMap {                                                                public:                                                                           using FunctionInfo = std::tuple
   
    ;            using Map = std::map
    
     ;                                                                                                                                                                                                                                            virtual ~KeywordMap() {                                                         }                                                                                                                                                               const Result
     
       FindFunction(const std::vector
      
       & args) const {        using android::base::StringPrintf;                                                                                                                              if (args.empty()) return Error() << "Keyword needed, but not provided";                                                                                         auto& keyword = args[0];                                                        auto num_args = args.size() - 1;                                                                                                                                auto function_info_it = map().find(keyword);               //在map表里，找到相同"do_mount"                     if (function_info_it == map().end()) {                                              return Error() << StringPrintf("Invalid keyword '%s'", keyword.c_str());        }                                                                                                                                                               auto function_info = function_info_it->second;                                                                                                                  auto min_args = std::get<0>(function_info);                                     auto max_args = std::get<1>(function_info);                                     if (min_args == max_args && num_args != min_args) {                                 return Error() << StringPrintf("%s requires %zu argument%s", keyword.c_str(), min_args,                                           (min_args > 1 || min_args == 0) ? "s" : "");        }                                                                                                                                                               if (num_args < min_args || num_args > max_args) {                                   if (max_args == std::numeric_limits
       
        ::max()) {                   return Error() << StringPrintf("%s requires at least %zu argument%s",                                               keyword.c_str(), min_args, min_args > 1 ? "s" : "");            } else {                                                                            return Error() << StringPrintf("%s requires between %zu and %zu arguments",                                               keyword.c_str(), min_args, max_args);            }                                                                           }                                                                                                                                                               return std::get
        
         (function_info); //function_info定义是std::tuple
         
          ， //function_info是Fuction实例化,比如 {1, 4, {true, do_mkdir} //则会返回do_mkdir函数的地址 } private: // Map of keyword -> // (minimum number of arguments, maximum number of arguments, function pointer) virtual const Map& map() const = 0; };
         
        
       
      
     
    
   

Map使用std::map的key值是函数名，比如"do_mount",还有个FunctionInfo类型。

Function

static const KeywordMap
   
    * function_map_;using BuiltinFunction = std::function
    
     &)>; // Builtin-function-map start                                                   const BuiltinFunctionMap::Map& BuiltinFunctionMap::map() const {                    constexpr std::size_t kMax = std::numeric_limits
     
      ::max();           // clang-format off                                                             static const Map builtin_functions = {                                              {"bootchart",               {1,     1,    {false,  do_bootchart}}},             {"chmod",                   {2,     2,    {true,   do_chmod}}},                 {"chown",                   {2,     3,    {true,   do_chown}}},                 {"class_reset",             {1,     1,    {false,  do_class_reset}}},           {"class_restart",           {1,     1,    {false,  do_class_restart}}},         {"class_start",             {1,     1,    {false,  do_class_start}}},           {"class_stop",              {1,     1,    {false,  do_class_stop}}},            {"copy",                    {2,     2,    {true,   do_copy}}},                  {"domainname",              {1,     1,    {true,   do_domainname}}},            {"enable",                  {1,     1,    {false,  do_enable}}},                {"exec",                    {1,     kMax, {false,  do_exec}}},                  {"exec_background",         {1,     kMax, {false,  do_exec_background}}},        {"exec_start",              {1,     1,    {false,  do_exec_start}}},            {"export",                  {2,     2,    {false,  do_export}}},                {"hostname",                {1,     1,    {true,   do_hostname}}},              {"ifup",                    {1,     1,    {true,   do_ifup}}},                  {"init_user0",              {0,     0,    {false,  do_init_user0}}},            {"insmod",                  {1,     kMax, {true,   do_insmod}}},                {"installkey",              {1,     1,    {false,  do_installkey}}},            {"load_persist_props",      {0,     0,    {false,  do_load_persist_props}}},        {"load_system_props",       {0,     0,    {false,  do_load_system_props}}},        {"loglevel",                {1,     1,    {false,  do_loglevel}}},              {"mkdir",                   {1,     4,    {true,   do_mkdir}}},
     
    
   

在使用KeywordMap模板类时候，传入BuiltinFunction参数，BuiltinFunction使用std::function,返回是int,传入的onst std::vectorstd::string&参数。

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