Join.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Containers/StringView.h"
#include "Misc/StringBuilder.h"
#include "Templates/IdentityFunctor.h"
#include "Templates/Invoke.h"
 
namespace UE::String::Private
{
 
template <typename RangeType, typename ProjectionType, typename DelimiterType, typename QuoteType>
struct TJoinQuotedBy
{
    RangeType&& Range;
    ProjectionType Projection;
    DelimiterType&& Delimiter;
    QuoteType&& Quote;
};
 
template <typename RangeType, typename ProjectionType, typename DelimiterType>
struct TJoinBy
{
    RangeType&& Range;
    ProjectionType Projection;
    DelimiterType&& Delimiter;
};
 
} // UE::String::Private
 
namespace UE::String
{
 
/**
 * Create an object that can be appended to a string builder to append every element of the range
 * to the builder, separating the elements by the delimiter and surrounding every element on both
 * sides with a quote.
 *
 * @param Range        The range of elements to join and append.
 * @param Projection   The projection to apply to the elements before appending them.
 * @param Delimiter    The delimiter to append as a separator for the elements.
 * @param Quote        The quote to append on both sides of each element.
 *
 * @return An anonymous object to append to a string builder.
 */
template <typename RangeType, typename ProjectionType, typename DelimiterType, typename QuoteType>
inline auto JoinQuotedBy(RangeType&& Range, ProjectionType Projection, DelimiterType&& Delimiter, QuoteType&& Quote)
    -> Private::TJoinQuotedBy<RangeType, ProjectionType, DelimiterType, QuoteType>
{
    return {Forward<RangeType>(Range), MoveTemp(Projection), Forward<DelimiterType>(Delimiter), Forward<QuoteType>(Quote)};
}
 
/**
 * Append every element of the range to the builder, separating the elements by the delimiter, and
 * surrounding every element on each side with the given quote.
 *
 * @param Range        The range of elements to join and append.
 * @param Projection   The projection to apply to the elements before appending them.
 * @param Delimiter    The delimiter to append as a separator for the elements.
 * @param Quote        The quote to append on both sides of each element.
 * @param Builder      The builder to append to.
 *
 * @return The builder, to allow additional operations to be composed with this one.
 */
template <typename RangeType, typename ProjectionType, typename DelimiterType, typename QuoteType, typename CharType>
inline TStringBuilderBase<CharType>& JoinQuotedByTo(
    RangeType&& Range,
    ProjectionType Projection,
    DelimiterType&& Delimiter,
    QuoteType&& Quote,
    TStringBuilderBase<CharType>& Builder)
{
    bool bFirst = true;
    for (auto&& Elem : Forward<RangeType>(Range))
    {
        if (bFirst)
        {
            bFirst = false;
        }
        else
        {
            Builder << Delimiter;
        }
        Builder << Quote << Invoke(Projection, Elem) << Quote;
    }
    return Builder;
}
 
/**
 * Create an object that can be appended to a string builder to append every element of the range
 * to the builder, separating the elements by the delimiter and surrounding every element on both
 * sides with a quote.
 *
 * @param Range       The range of elements to join and append.
 * @param Delimiter   The delimiter to append as a separator for the elements.
 * @param Quote       The quote to append on both sides of each element.
 *
 * @return An anonymous object to append to a string builder.
 */
template <typename RangeType, typename DelimiterType, typename QuoteType>
inline auto JoinQuoted(RangeType&& Range, DelimiterType&& Delimiter, QuoteType&& Quote)
    -> Private::TJoinQuotedBy<RangeType, FIdentityFunctor, DelimiterType, QuoteType>
{
    return {Forward<RangeType>(Range), FIdentityFunctor(), Forward<DelimiterType>(Delimiter), Forward<QuoteType>(Quote)};
}
 
/**
 * Append every element of the range to the builder, separating the elements by the delimiter, and
 * surrounding every element on each side with the given quote.
 *
 * @param Range       The range of elements to join and append.
 * @param Delimiter   The delimiter to append as a separator for the elements.
 * @param Quote       The quote to append on both sides of each element.
 * @param Builder     The builder to append to.
 *
 * @return The builder, to allow additional operations to be composed with this one.
 */
template <typename RangeType, typename DelimiterType, typename QuoteType, typename CharType>
inline TStringBuilderBase<CharType>& JoinQuotedTo(
    RangeType&& Range,
    DelimiterType&& Delimiter,
    QuoteType&& Quote,
    TStringBuilderBase<CharType>& Builder)
{
    return JoinQuotedByTo(Forward<RangeType>(Range), FIdentityFunctor(), Forward<DelimiterType>(Delimiter), Forward<QuoteType>(Quote), Builder);
}
 
/**
 * Create an object that can be appended to a string builder to append every element of the range
 * to the builder, separating the elements by the delimiter.
 *
 * @param Range        The range of elements to join and append.
 * @param Projection   The projection to apply to the elements before appending them.
 * @param Delimiter    The delimiter to append as a separator for the elements.
 *
 * @return An anonymous object to append to a string builder.
 */
template <typename RangeType, typename ProjectionType, typename DelimiterType>
inline auto JoinBy(RangeType&& Range, ProjectionType Projection, DelimiterType&& Delimiter)
    -> Private::TJoinBy<RangeType, ProjectionType, DelimiterType>
{
    return {Forward<RangeType>(Range), MoveTemp(Projection), Forward<DelimiterType>(Delimiter)};
}
 
/**
 * Append every element of the range to the builder, separating the elements by the delimiter.
 *
 * @param Range        The range of elements to join and append.
 * @param Projection   The projection to apply to the elements before appending them.
 * @param Delimiter    The delimiter to append as a separator for the elements.
 * @param Builder      The builder to append to.
 *
 * @return The builder, to allow additional operations to be composed with this one.
 */
template <typename RangeType, typename ProjectionType, typename DelimiterType, typename CharType>
inline TStringBuilderBase<CharType>& JoinByTo(
    RangeType&& Range,
    ProjectionType Projection,
    DelimiterType&& Delimiter,
    TStringBuilderBase<CharType>& Builder)
{
    bool bFirst = true;
    for (auto&& Elem : Forward<RangeType>(Range))
    {
        if (bFirst)
        {
            bFirst = false;
        }
        else
        {
            Builder << Delimiter;
        }
        Builder << Invoke(Projection, Elem);
    }
    return Builder;
}
 
/**
 * Create an object that can be appended to a string builder to append every element of the range
 * to the builder, separating the elements by the delimiter.
 *
 * @param Range        The range of elements to join and append.
 * @param Delimiter    The delimiter to append as a separator for the elements.
 *
 * @return An anonymous object to append to a string builder.
 */
template <typename RangeType, typename DelimiterType>
inline auto Join(RangeType&& Range, DelimiterType&& Delimiter)
    -> Private::TJoinBy<RangeType, FIdentityFunctor, DelimiterType>
{
    return {Forward<RangeType>(Range), FIdentityFunctor(), Forward<DelimiterType>(Delimiter)};
}
 
/**
 * Append every element of the range to the builder, separating the elements by the delimiter.
 *
 * @param Range        The range of elements to join and append.
 * @param Delimiter    The delimiter to append as a separator for the elements.
 * @param Builder      The builder to append to.
 *
 * @return The builder, to allow additional operations to be composed with this one.
 */
template <typename RangeType, typename DelimiterType, typename CharType>
inline TStringBuilderBase<CharType>& JoinTo(RangeType&& Range, DelimiterType&& Delimiter, TStringBuilderBase<CharType>& Builder)
{
    return JoinByTo(Forward<RangeType>(Range), FIdentityFunctor(), Forward<DelimiterType>(Delimiter), Builder);
}
 
} // UE::String
 
namespace UE::String::Private
{
 
template <typename RangeType, typename ProjectionType, typename DelimiterType, typename QuoteType, typename CharType>
inline TStringBuilderBase<CharType>& operator<<(
    TStringBuilderBase<CharType>& Builder,
    Private::TJoinQuotedBy<RangeType, ProjectionType, DelimiterType, QuoteType>&& Adapter)
{
    return JoinQuotedByTo(
        Forward<RangeType>(Adapter.Range),
        MoveTemp(Adapter.Projection),
        Forward<DelimiterType>(Adapter.Delimiter),
        Forward<QuoteType>(Adapter.Quote),
        Builder);
}
 
template <typename RangeType, typename ProjectionType, typename DelimiterType, typename CharType>
inline TStringBuilderBase<CharType>& operator<<(
    TStringBuilderBase<CharType>& Builder,
    Private::TJoinBy<RangeType, ProjectionType, DelimiterType>&& Adapter)
{
    return JoinByTo(Forward<RangeType>(Adapter.Range), MoveTemp(Adapter.Projection), Forward<DelimiterType>(Adapter.Delimiter), Builder);
}
 
} // UE::String::Private