StringCase.hpp

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// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2026 Caleb Buahin
//
// 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 OPENSWMM_ENGINE_STRING_CASE_HPP
#define OPENSWMM_ENGINE_STRING_CASE_HPP
 
#include <cstddef>
#include <cstdint>
#include <string_view>
 
namespace openswmm {

inline constexpr char ci_upper(char c) noexcept {
    return (c >= 'a' && c <= 'z') ? static_cast<char>(c & ~32) : c;
}

inline bool ieq(std::string_view a, std::string_view b) noexcept {
    if (a.size() != b.size())
        return false;
    for (std::size_t i = 0; i < a.size(); ++i)
        if (ci_upper(a[i]) != ci_upper(b[i]))
            return false;
    return true;
}

struct CiHash {
    using is_transparent = void;
    std::size_t operator()(std::string_view s) const noexcept {
        std::uint64_t h = 14695981039346656037ull;
        for (char c : s) {
            h ^= static_cast<std::uint64_t>(static_cast<unsigned char>(ci_upper(c)));
            h *= 1099511628211ull;
        }
        return static_cast<std::size_t>(h);
    }
};

struct CiEqual {
    using is_transparent = void;
    bool operator()(std::string_view a, std::string_view b) const noexcept { return ieq(a, b); }
};
 
} /* namespace openswmm */
 
#endif /* OPENSWMM_ENGINE_STRING_CASE_HPP */