ALib.Strings.StdFunctors.H

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//==================================================================================================
/// \file
/// This header-file is part of the \aliblong.
///
/// \emoji :copyright: 2013-2025 A-Worx GmbH, Germany.
/// Published under \ref mainpage_license "Boost Software License".
//==================================================================================================
#ifndef H_ALIB_STRINGS_STDFUNCTORS
#define H_ALIB_STRINGS_STDFUNCTORS
#pragma once
#ifndef INL_ALIB
#   include "alib/alib.inl"
#endif
#if ALIB_STRINGS
#include "ALib.Lang.H"
#include "ALib.Strings.H"
 
#if DOXYGEN
    namespace alib::strings {
    /// This namespace contains sub-namespaces that provide compatibility of 3rd-party types and
    /// module \alib_strings_nl.<br>
    /// The entities of those namespaces become available with the inclusion of specific headers
    /// that import a certain C++20 Module or inject the functionality into a namespace in a
    /// traditional fashion, for example, header \implude{Strings.StdFunctors}.
    namespace compatibility {
 
    /// This namespace documents compatibility features of \alib_strings_nl and the
    /// standard C++ class library found in namespace \c std.
    namespace std {
}}}
#endif
 
// #################################################################################################
// #### std::hash and std::equal_to for ALib string types
// #################################################################################################
#if DOXYGEN
    namespace alib::strings::compatibility::std {
#else
    namespace std {
#endif
 
//==================================================================================================
/// Specialization of functor <c>std::hash</c> for type \alib{strings;TString<TChar>;String}.
/// Note that this specialization can also be used in combination with derived string-types, like
/// \alib{strings;TAString<TChar>;AString}.
///
/// This specialization is provided with the inclusion of header-file
/// \implude{Strings.StdFunctors}.<br>
///
/// \note
///   While the documentation indicates namespace <c>alib::strings::compatibility::std</c>,
///   the true location is namespace <c>std</c> (as mandatory).
///
/// @tparam TChar  The character type of the string.
//==================================================================================================
template<typename TChar>
struct hash<alib::strings::TString<TChar>> {
    /// Calculates the hash code for \alib strings.
    /// @param src The string object to hash.
    /// @return The hash code.
    std::size_t operator()(const alib::strings::TString<TChar>& src) const
    { return src.Hashcode(); }
};
 
//==================================================================================================
/// Specialization of functor <c>std::equal_to</c> for type \alib{strings;TString<TChar>;String}.
/// Note that this specialization can also be used in combination with derived string-types, like
/// \alib{strings;TAString<TChar>;AString}.
///
/// This specialization is provided with the inclusion of header-file
/// \implude{Strings.StdFunctors}.<br>
///
/// \note
///   While the documentation indicates namespace <c>alib::strings::compatibility::std</c>,
///   the true location is namespace <c>std</c> (as mandatory).
///
/// @tparam TChar  The character type of the strings to compare.
//==================================================================================================
template<typename TChar>
struct equal_to<alib::strings::TString<TChar>>
{
    /// Invokes  \alib{strings;TString::Equals;String::Equals} on \p{lhs}, passing \p{rhs}
    /// and returns the result.
    /// @param lhs The first string object.
    /// @param rhs The second string object.
    /// @return The result of the comparison.
    bool operator()(const alib::strings::TString<TChar>& lhs,
                    const alib::strings::TString<TChar>& rhs   ) const
    {
        return lhs.Equals( rhs );
    }
};
 
//==================================================================================================
/// Specialization of functor <c>std::less</c> for strings of templated character type.
///
/// For the comparison, \alib{strings::TString;CompareTo} is invoked on \p{lhs} with passing
/// \p{rhs}.
///
/// This specialization is provided with the inclusion of header-file
/// \implude{Strings.StdFunctors}.<br>
///
/// \note
///   While the documentation indicates namespace <c>alib::strings::compatibility::std</c>,
///   the true location is namespace <c>std</c> (as mandatory).
///
/// @tparam TChar  The character type of the strings to compare.
//==================================================================================================
template<typename TChar>
struct less<alib::strings::TString<TChar>>
{
    /// Compares the two given strings.
    /// @param lhs The left-hand side string.
    /// @param rhs The right-hand side string.
    /// @return The result of the comparison.
    bool operator()(const alib::strings::TString<TChar>& lhs,
                    const alib::strings::TString<TChar>& rhs) const
    {
        return  lhs.CompareTo(rhs) < 0;
    }
};
 
#if !DOXYGEN
} // namespace [std]
namespace alib {
#endif
 
//==================================================================================================
/// Functor that can be used as an explicitly given replacement for <c>std::hash</c> with template
/// types (containers) found in namespace \c std.<br>
/// While the specialization of <c>std::hash</c> for type \alib{strings;TString<TChar>;String},
/// which is used by the default values of template arguments of the corresponding types in namespace
/// \c std, performs a case-sensitive hash code calculation, this version creates the same
/// hash code for two strings that only differ in the letter case of one or more characters.
///
/// Note that this specialization can also be used in combination with derived string-types, like
/// \alib{strings;TAString<TChar>;AString}.
///
/// This functor is provided with the inclusion of header-file
/// \implude{Strings.StdFunctors}.
///
/// \note
///   While the documentation indicates namespace <c>alib::strings::compatibility::std</c>,
///   the true location is namespace <c>std</c> (as mandatory).
///
/// @tparam TChar  The character type of the string. Defaults to \alib{characters;character}.
//==================================================================================================
template<typename TChar= characters::character>
struct hash_string_ignore_case
{
    /// Calculates the hash code \alib strings, ignoring the letter case.
    /// @param src The string object to hash.
    /// @return The hash code.
    size_t operator()(const strings::TString<TChar>& src) const
    {
        return src.HashcodeIgnoreCase();
    }
};
 
//==================================================================================================
/// Functor that can be used as an explicitly given replacement for <c>std::equal_to</c> with template
/// types (containers) found in namespace \c std.<br>
/// While the specialization of <c>std::equal_to</c> for type \alib{strings;TString<TChar>;String},
/// which is used by the default values of template arguments of the corresponding types in namespace
/// \c std, performs a case-sensitive comparison, this version ignores the letter case of the
/// characters of the given strings.
///
/// Note that this specialization can also be used in combination with derived string-types, like
/// \alib{strings;TAString<TChar>;AString}.
///
/// This functor is provided with the inclusion of header-file
/// \implude{Strings.StdFunctors}.
///
/// \note
///   While the documentation indicates namespace <c>alib::strings::compatibility::std</c>,
///   the true location is namespace <c>alib</c>.
///
/// @tparam TChar  The character type of the strings to compare.
///                Defaults to \alib{characters;character}.
//==================================================================================================
template<typename TChar= characters::character>
struct equal_to_string_ignore_case
{
    /// Invokes \alib{strings;TString::Equals;String::Equals} on \p{lhs}, passing \p{rhs}
    /// and returns the result.
    ///
    /// @param lhs The first string object.
    /// @param rhs The second string object.
    /// @return The result of the comparison.
    bool operator()(const strings::TString<TChar>& lhs,
                    const strings::TString<TChar>& rhs  ) const
    {
        return lhs.template Equals<alib::CHK, lang::Case::Ignore>( rhs );
    }
};
 
//==================================================================================================
/// Specialization of functor <c>std::less</c> for strings of templated character type.
///
/// For the comparison, \alib{strings::TString;CompareTo;CompareTo<Case::Ignore>} is invoked on
/// \p{lhs} with passing \p{rhs}.
///
/// This specialization is provided with the inclusion of header-file
/// \implude{Strings.StdFunctors}.<br>
///
/// \note
///   While the documentation indicates namespace <c>alib::strings::compatibility::std</c>,
///   the true location is namespace <c>std</c> (as mandatory).
///
/// @tparam TChar  The character type of the strings to compare.
///                Defaults to \alib{characters;character}.
//==================================================================================================
template<typename TChar= characters::character>
struct less_string_ignore_case
{
    /// Compares the two given strings.
    /// @param lhs The left-hand side string.
    /// @param rhs The right-hand side string.
    /// @return \c true if \p{lhs} is less than \p{rhs}.
    bool operator()(const strings::TString<TChar>& lhs,
                    const strings::TString<TChar>& rhs) const
    {
        return  lhs.template CompareTo<lang::Case::Ignore>( rhs ) < 0;
    }
};
 
} // namespace alib
 
#endif // ALIB_STRINGS
#endif // H_ALIB_STRINGS_STDFUNCTORS