88 lines
2.9 KiB
C++
88 lines
2.9 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <map>
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#include <string>
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#include <vector>
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#include "result.h"
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namespace android {
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namespace init {
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// Every init builtin, init service option, and ueventd option has a minimum and maximum number of
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// arguments. These must be checked both at run time for safety and also at build time for
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// correctness in host_init_verifier. Instead of copying and pasting the boiler plate code that
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// does this check into each function, it is abstracted in KeywordMap<>. This class maps keywords
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// to functions and checks that the number of arguments provided falls in the correct range or
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// returns an error otherwise.
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// Value is the return value of Find(), which is typically either a single function or a struct with
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// additional information.
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template <typename Value>
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class KeywordMap {
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public:
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struct MapValue {
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size_t min_args;
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size_t max_args;
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Value value;
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};
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KeywordMap() {}
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KeywordMap(std::initializer_list<std::pair<const std::string, MapValue>> init) : map_(init) {}
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Result<Value> Find(const std::vector<std::string>& args) const {
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if (args.empty()) return Error() << "Keyword needed, but not provided";
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auto& keyword = args[0];
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auto num_args = args.size() - 1;
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auto result_it = map_.find(keyword);
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if (result_it == map_.end()) {
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return Errorf("Invalid keyword '{}'", keyword);
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}
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auto result = result_it->second;
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auto min_args = result.min_args;
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auto max_args = result.max_args;
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if (min_args == max_args && num_args != min_args) {
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return Errorf("{} requires {} argument{}", keyword, min_args,
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(min_args > 1 || min_args == 0) ? "s" : "");
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}
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if (num_args < min_args || num_args > max_args) {
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if (max_args == std::numeric_limits<decltype(max_args)>::max()) {
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return Errorf("{} requires at least {} argument{}", keyword, min_args,
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min_args > 1 ? "s" : "");
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} else {
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return Errorf("{} requires between {} and {} arguments", keyword, min_args,
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max_args);
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}
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}
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return result.value;
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}
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private:
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std::map<std::string, MapValue> map_;
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};
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} // namespace init
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} // namespace android
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