eternalString.h

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//
// Copyright 2026 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifndef PXR_BASE_TF_ETERNAL_STRING_H
#define PXR_BASE_TF_ETERNAL_STRING_H
 
 
#include "pxr/pxr.h"
#include "pxr/base/tf/api.h"
 
#include <cstddef>
#include <iosfwd>
#include <string>
#include <string_view>
 
PXR_NAMESPACE_OPEN_SCOPE
 
class TfEternalString
{
public:
    TF_API TfEternalString();
 
    TF_API static TfEternalString Immortalize(std::string_view content);
 
    char const *c_str()  const { return _str->c_str(); }
    char const *data()   const { return _str->data();  }
    size_t      size()   const { return _str->size();  }
    size_t      length() const { return _str->size();  }
    bool        empty()  const { return _str->empty(); }
 
    std::string const &GetString() const { return *_str; }
 
    std::string_view GetStringView() const { return *_str; }
 
    operator std::string const &() const { return *_str; }
    operator std::string_view() const { return *_str; }
 
 
    friend std::string operator+(TfEternalString a, std::string_view b) {
        return _Cat(a.data(), a.size(), b.data(), b.size());
    }
    friend std::string operator+(std::string_view a, TfEternalString b) {
        return _Cat(a.data(), a.size(), b.data(), b.size());
    }
    friend std::string operator+(TfEternalString a, TfEternalString b) {
        return _Cat(a.data(), a.size(), b.data(), b.size());
    }
 
    friend bool operator==(TfEternalString a, TfEternalString b) {
        return a._str == b._str;
    }
    friend bool operator==(TfEternalString a, std::string_view b) {
        return a.GetStringView() == b;
    }
    friend bool operator==(std::string_view a, TfEternalString b) {
        return a == b.GetStringView();
    }
    friend bool operator!=(TfEternalString a, TfEternalString b) {
        return !(a == b);
    }
    friend bool operator!=(TfEternalString a, std::string_view b) {
        return !(a == b);
    }
    friend bool operator!=(std::string_view a, TfEternalString b) {
        return !(a == b);
    }
 
    template <class HashState>
    friend void TfHashAppend(HashState &h, TfEternalString s) {
        h.Append(s._str);
    }
 
    TF_API friend std::ostream &operator<<(std::ostream &o, TfEternalString s);
 
 
private:
    explicit TfEternalString(std::string const *str) : _str(str) {}
 
    TF_API static std::string
    _Cat(char const *a, size_t aLen, char const *b, size_t bLen);
 
    std::string const *_str;
};
 
PXR_NAMESPACE_CLOSE_SCOPE
 
#endif // PXR_BASE_TF_ETERNAL_STRING_H