adamdebreceni commented on a change in pull request #797: URL: https://github.com/apache/nifi-minifi-cpp/pull/797#discussion_r446027617
########## File path: libminifi/include/utils/ValueParser.h ########## @@ -0,0 +1,194 @@ +/** + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenseas/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef LIBMINIFI_INCLUDE_UTILS_VALUEPARSER_H_ +#define LIBMINIFI_INCLUDE_UTILS_VALUEPARSER_H_ + +#include <exception> +#include <string> +#include <cstring> +#include <vector> +#include <cstdlib> +#include <type_traits> +#include <limits> + +#include "PropertyErrors.h" +#include "GeneralUtils.h" + +namespace org { +namespace apache { +namespace nifi { +namespace minifi { +namespace utils { +namespace internal { + +class ValueParser { + private: + template<typename From, typename To, typename = void> + struct is_non_narrowing_convertible : std::false_type { + static_assert(std::is_integral<From>::value && std::is_integral<To>::value, "Checks only integral values"); + }; + + template<typename From, typename To> + struct is_non_narrowing_convertible<From, To, void_t<decltype(To{std::declval<From>()})>> : std::true_type { + static_assert(std::is_integral<From>::value && std::is_integral<To>::value, "Checks only integral values"); + }; + + public: + explicit ValueParser(const std::string& str, std::size_t offset = 0) : str(str), offset(offset) {} + + template<typename Out> + ValueParser& parseInt(Out& out) { + static_assert(is_non_narrowing_convertible<int, Out>::value, "Expected lossless conversion from int"); + long result; // NOLINT + auto len = safeCallConverter(std::strtol, result); + if (len == 0) { + throw ParseException("Couldn't parse int"); + } + if (result < (std::numeric_limits<int>::min)() || result > (std::numeric_limits<int>::max)()) { + throw ParseException("Cannot convert long to int"); + } + offset += len; + out = {static_cast<int>(result)}; + return *this; + } + + template<typename Out> + ValueParser& parseLong(Out& out) { + static_assert(is_non_narrowing_convertible<long, Out>::value, "Expected lossless conversion from long"); // NOLINT + long result; // NOLINT + auto len = safeCallConverter(std::strtol, result); + if (len == 0) { + throw ParseException("Couldn't parse long"); + } + offset += len; + out = {result}; + return *this; + } + + template<typename Out> + ValueParser& parseLongLong(Out& out) { + static_assert(is_non_narrowing_convertible<long long, Out>::value, "Expected lossless conversion from long long"); // NOLINT + long long result; // NOLINT + auto len = safeCallConverter(std::strtoll, result); + if (len == 0) { + throw ParseException("Couldn't parse long long"); + } + offset += len; + out = {result}; + return *this; + } + + template<typename Out> + ValueParser& parseUInt32(Out& out) { + static_assert(is_non_narrowing_convertible<uint32_t, Out>::value, "Expected lossless conversion from uint32_t"); + skipWhitespace(); + if (offset < str.length() && str[offset] == '-') { + throw ParseException("Not an unsigned long"); + } + unsigned long result; // NOLINT + auto len = safeCallConverter(std::strtoul, result); + if (len == 0) { + throw ParseException("Couldn't parse uint32_t"); + } + if (result > (std::numeric_limits<uint32_t>::max)()) { + throw ParseException("Cannot convert unsigned long to uint32_t"); + } + offset += len; + out = {static_cast<uint32_t>(result)}; + return *this; + } + + template<typename Out> + ValueParser& parseUnsignedLongLong(Out& out) { + static_assert(is_non_narrowing_convertible<unsigned long long, Out>::value, "Expected lossless conversion from unsigned long long"); // NOLINT + skipWhitespace(); + if (offset < str.length() && str[offset] == '-') { + throw ParseException("Not an unsigned long"); + } + unsigned long long result; // NOLINT + auto len = safeCallConverter(std::strtoull, result); + if (len == 0) { + throw ParseException("Couldn't parse unsigned long long"); + } + offset += len; + out = {result}; + return *this; + } + + template<typename Out> + ValueParser& parseBool(Out& out) { Review comment: I dig it, the only problem with this specific approach is that, template function partial specialization is a no-go, but will think about something like this ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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