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      1 /*
      2  * Copyright (C) 2015 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 _INIT_KEYWORD_MAP_H_
     18 #define _INIT_KEYWORD_MAP_H_
     19 
     20 #include <map>
     21 #include <string>
     22 
     23 #include <android-base/stringprintf.h>
     24 
     25 #include "result.h"
     26 
     27 namespace android {
     28 namespace init {
     29 
     30 template <typename Function>
     31 class KeywordMap {
     32   public:
     33     using FunctionInfo = std::tuple<std::size_t, std::size_t, Function>;
     34     using Map = std::map<std::string, FunctionInfo>;
     35 
     36     virtual ~KeywordMap() {
     37     }
     38 
     39     const Result<Function> FindFunction(const std::vector<std::string>& args) const {
     40         using android::base::StringPrintf;
     41 
     42         if (args.empty()) return Error() << "Keyword needed, but not provided";
     43 
     44         auto& keyword = args[0];
     45         auto num_args = args.size() - 1;
     46 
     47         auto function_info_it = map().find(keyword);
     48         if (function_info_it == map().end()) {
     49             return Error() << StringPrintf("Invalid keyword '%s'", keyword.c_str());
     50         }
     51 
     52         auto function_info = function_info_it->second;
     53 
     54         auto min_args = std::get<0>(function_info);
     55         auto max_args = std::get<1>(function_info);
     56         if (min_args == max_args && num_args != min_args) {
     57             return Error() << StringPrintf("%s requires %zu argument%s", keyword.c_str(), min_args,
     58                                            (min_args > 1 || min_args == 0) ? "s" : "");
     59         }
     60 
     61         if (num_args < min_args || num_args > max_args) {
     62             if (max_args == std::numeric_limits<decltype(max_args)>::max()) {
     63                 return Error() << StringPrintf("%s requires at least %zu argument%s",
     64                                                keyword.c_str(), min_args, min_args > 1 ? "s" : "");
     65             } else {
     66                 return Error() << StringPrintf("%s requires between %zu and %zu arguments",
     67                                                keyword.c_str(), min_args, max_args);
     68             }
     69         }
     70 
     71         return std::get<Function>(function_info);
     72     }
     73 
     74   private:
     75     // Map of keyword ->
     76     // (minimum number of arguments, maximum number of arguments, function pointer)
     77     virtual const Map& map() const = 0;
     78 };
     79 
     80 }  // namespace init
     81 }  // namespace android
     82 
     83 #endif
     84