lexical_casts.hpp

// Copyright 2023 ros2_control Development Team
//
// Licensed 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/licenses/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 HARDWARE_INTERFACE__LEXICAL_CASTS_HPP_
#define HARDWARE_INTERFACE__LEXICAL_CASTS_HPP_
 
#include <regex>
#include <sstream>
#include <stdexcept>
#include <string>
#include <type_traits>
#include <vector>
 
namespace hardware_interface
{
 
double stod(const std::string & s);
 
std::string to_lower_case(const std::string & string);
 
bool parse_bool(const std::string & bool_string);
 
template <typename T>
std::vector<T> parse_array(const std::string & array_string)
{
  // Use regex to check for a flat array: starts with [, ends with ], no nested brackets
  const std::regex array_regex(R"(^\[\s*([^\[\]]*\s*(,\s*[^\[\]]+\s*)*)?\]$)");
  if (!std::regex_match(array_string, array_regex))
  {
    throw std::invalid_argument(
      "String must be a flat array: starts with '[' and ends with ']', no nested arrays");
  }
 
  // Use regex for the expression that either empty or contains only spaces
  const std::regex empty_or_spaces_regex(R"(^\[\s*\]$)");
  if (std::regex_match(array_string, empty_or_spaces_regex))
  {
    return {};  // Return empty array if input is "[]"
  }
 
  // Use regex to find cases of comma-separated but only whitespaces or no spaces between them like
  // "[,]" "[a,b,,c]"
  const std::regex comma_separated_regex(R"(^\[\s*([^,\s]+(\s*,\s*[^,\s]+)*)?\s*\]$)");
  if (!std::regex_match(array_string, comma_separated_regex))
  {
    throw std::invalid_argument(
      "String must be a flat array with comma-separated values and no spaces between them");
  }
 
  std::vector<T> result = {};
  if (array_string == "[]")
  {
    return result;  // Return empty array if input is "[]"
  }
 
  // regex for comma separated values and no spaces between them or just content like "[a,b,c]" or
  // "[a]" or "[a, b, c]"
  const std::regex value_regex(R"([^\s,\[\]]+)");
  auto begin = std::sregex_iterator(array_string.begin(), array_string.end(), value_regex);
  auto end = std::sregex_iterator();
 
  for (auto it = begin; it != end; ++it)
  {
    const std::string value_str = it->str();  // Get the first capturing group
    if constexpr (std::is_same_v<T, std::string>)
    {
      result.push_back(value_str);
    }
    else if constexpr (std::is_same_v<T, bool>)
    {
      result.push_back(parse_bool(value_str));
    }
    else if constexpr (std::is_floating_point_v<T> || std::is_integral_v<T>)
    {
      try
      {
        const T value = static_cast<T>(hardware_interface::stod(value_str));
        result.push_back(value);
      }
      catch (const std::exception &)
      {
        throw std::invalid_argument(
          "Failed converting string to floating point or integer: " + value_str);
      }
    }
    else
    {
      throw std::invalid_argument("Unsupported type for parsing: " + std::string(typeid(T).name()));
    }
  }
  return result;
}
 
std::vector<std::string> parse_string_array(const std::string & string_array_string);
 
}  // namespace hardware_interface
 
#endif  // HARDWARE_INTERFACE__LEXICAL_CASTS_HPP_