DynamoDB.SourceGenerator/src/DynamoDBGenerator.SourceGenerator/Extensions/EnumerableExtensions.cs at bfef66fa9a0badd62056ee00e07792f54e91eaf6 · inputfalken/DynamoDB.SourceGenerator · GitHub

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namespace DynamoDBGenerator.SourceGenerator.Extensions;

public static class EnumerableExtensions
{
    public static IEnumerable<T> AllButLast<T>(this IEnumerable<T> enumerable, Func<T, T> @default)
    {
        var buffer = default(T);
        var isBuffered = false;

        foreach (var item in enumerable)
        {
            if (isBuffered)
                yield return @default(buffer!);

            isBuffered = true;
            buffer = item;
        }

        if (isBuffered) yield return buffer!;
    }

    public static IEnumerable<TResult> AllAndLast<T, TResult>(this IEnumerable<T> enumerable, Func<T, TResult> @default,
        Func<T, TResult> onLast)
    {
        var buffer = default(T);
        var isBuffered = false;

        foreach (var item in enumerable)
        {
            if (isBuffered)
                yield return @default(buffer!);

            isBuffered = true;
            buffer = item;
        }

        if (isBuffered) yield return onLast(buffer!);
    }
}