spectre.console/src/Spectre.Console/Rendering/Borders/Tables/HeavyTableBorder.cs

using System;

namespace Spectre.Console.Rendering
{
    /// <summary>
    /// Represents a heavy border.
    /// </summary>
    public sealed class HeavyTableBorder : TableBorder
    {
        /// <inheritdoc/>
        public override TableBorder? SafeBorder => TableBorder.Square;

        /// <inheritdoc/>
        public override string GetPart(TableBorderPart part)
        {
            return part switch
            {
                TableBorderPart.HeaderTopLeft => "┏",
                TableBorderPart.HeaderTop => "━",
                TableBorderPart.HeaderTopSeparator => "┳",
                TableBorderPart.HeaderTopRight => "┓",
                TableBorderPart.HeaderLeft => "┃",
                TableBorderPart.HeaderSeparator => "┃",
                TableBorderPart.HeaderRight => "┃",
                TableBorderPart.HeaderBottomLeft => "┣",
                TableBorderPart.HeaderBottom => "━",
                TableBorderPart.HeaderBottomSeparator => "╋",
                TableBorderPart.HeaderBottomRight => "┫",
                TableBorderPart.CellLeft => "┃",
                TableBorderPart.CellSeparator => "┃",
                TableBorderPart.CellRight => "┃",
                TableBorderPart.FooterTopLeft => "┣",
                TableBorderPart.FooterTop => "━",
                TableBorderPart.FooterTopSeparator => "╋",
                TableBorderPart.FooterTopRight => "┫",
                TableBorderPart.FooterBottomLeft => "┗",
                TableBorderPart.FooterBottom => "━",
                TableBorderPart.FooterBottomSeparator => "┻",
                TableBorderPart.FooterBottomRight => "┛",
                _ => throw new InvalidOperationException("Unknown border part."),
            };
        }
    }
}