strings.hpp

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// Copyright (c) Microsoft Corporation. All rights reserved.
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <algorithm>
#include <cstring>
#include <string>
 
namespace Azure { namespace Core { namespace _internal {
 
  struct StringExtensions final
  {
    static constexpr char ToUpper(char c) noexcept
    {
      return (c < 'a' || c > 'z') ? c : c - ('a' - 'A');
    }
 
    static constexpr char ToLower(char c) noexcept
    {
      return (c < 'A' || c > 'Z') ? c : c + ('a' - 'A');
    }
 
    struct CaseInsensitiveComparator final
    {
      bool operator()(std::string const& lhs, std::string const& rhs) const
      {
        return std::lexicographical_compare(
            lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), [](auto l, auto r) {
              return ToLower(l) < ToLower(r);
            });
      }
    };
 
    static bool LocaleInvariantCaseInsensitiveEqual(
        std::string const& lhs,
        std::string const& rhs) noexcept
    {
      auto const rhsSize = rhs.size();
      if (lhs.size() != rhsSize)
      {
        return false;
      }
 
      auto const lhsData = lhs.c_str();
      auto const rhsData = rhs.c_str();
      for (size_t i = 0; i < rhsSize; ++i)
      {
        if (ToLower(lhsData[i]) != ToLower(rhsData[i]))
        {
          return false;
        }
      }
 
      return true;
    }
 
    static std::string ToLower(std::string src)
    {
      std::transform(src.begin(), src.end(), src.begin(), [](auto c) { return ToLower(c); });
      return src;
    }
 
    static std::string ToUpper(std::string src)
    {
      std::transform(src.begin(), src.end(), src.begin(), [](auto c) { return ToUpper(c); });
      return src;
    }
  };
 
}}} // namespace Azure::Core::_internal