spectre.console/src/Spectre.Console/Composition/Borders/AsciiBorder.cs

using System;

namespace Spectre.Console.Composition
{
    /// <summary>
    /// Represents an old school ASCII border.
    /// </summary>
    public sealed class AsciiBorder : Border
    {
        /// <inheritdoc/>
        protected override char GetBoxPart(BorderPart part)
        {
            return part switch
            {
                BorderPart.HeaderTopLeft => '+',
                BorderPart.HeaderTop => '-',
                BorderPart.HeaderTopSeparator => '-',
                BorderPart.HeaderTopRight => '+',
                BorderPart.HeaderLeft => '|',
                BorderPart.HeaderSeparator => '|',
                BorderPart.HeaderRight => '|',
                BorderPart.HeaderBottomLeft => '|',
                BorderPart.HeaderBottom => '-',
                BorderPart.HeaderBottomSeparator => '+',
                BorderPart.HeaderBottomRight => '|',
                BorderPart.CellLeft => '|',
                BorderPart.CellSeparator => '|',
                BorderPart.ColumnRight => '|',
                BorderPart.FooterBottomLeft => '+',
                BorderPart.FooterBottom => '-',
                BorderPart.FooterBottomSeparator => '-',
                BorderPart.FooterBottomRight => '+',
                _ => throw new InvalidOperationException("Unknown box part."),
            };
        }
    }
}