spectre.console/src/Spectre.Console/Composition/Border.cs

using System;
using System.Collections.Generic;
using System.Globalization;

namespace Spectre.Console.Composition
{
    /// <summary>
    /// Represents a border used by tables.
    /// </summary>
    public abstract class Border
    {
        private readonly Dictionary<BorderPart, char> _lookup;

        private static readonly Dictionary<BorderKind, Border> _borders = new Dictionary<BorderKind, Border>
        {
            { BorderKind.Ascii, new AsciiBorder() },
            { BorderKind.Square, new SquareBorder() },
        };

        /// <summary>
        /// Initializes a new instance of the <see cref="Border"/> class.
        /// </summary>
        protected Border()
        {
            _lookup = Initialize();
        }

        /// <summary>
        /// Gets a <see cref="Border"/> represented by the specified <see cref="BorderKind"/>.
        /// </summary>
        /// <param name="kind">The kind of border to get.</param>
        /// <returns>A <see cref="Border"/> instance representing the specified <see cref="BorderKind"/>.</returns>
        public static Border GetBorder(BorderKind kind)
        {
            if (!_borders.TryGetValue(kind, out var border))
            {
                throw new InvalidOperationException("Unknown border kind");
            }

            return border;
        }

        private Dictionary<BorderPart, char> Initialize()
        {
            var lookup = new Dictionary<BorderPart, char>();
            foreach (BorderPart part in Enum.GetValues(typeof(BorderPart)))
            {
                lookup.Add(part, GetBoxPart(part));
            }

            return lookup;
        }

        /// <summary>
        /// Gets the string representation of a specific border part.
        /// </summary>
        /// <param name="part">The part to get a string representation for.</param>
        /// <param name="count">The number of repetitions.</param>
        /// <returns>A string representation of the specified border part.</returns>
        public string GetPart(BorderPart part, int count)
        {
            return new string(GetBoxPart(part), count);
        }

        /// <summary>
        /// Gets the string representation of a specific border part.
        /// </summary>
        /// <param name="part">The part to get a string representation for.</param>
        /// <returns>A string representation of the specified border part.</returns>
        public string GetPart(BorderPart part)
        {
            return _lookup[part].ToString(CultureInfo.InvariantCulture);
        }

        /// <summary>
        /// Gets the character representing the specified border part.
        /// </summary>
        /// <param name="part">The part to get the character representation for.</param>
        /// <returns>A character representation of the specified border part.</returns>
        protected abstract char GetBoxPart(BorderPart part);
    }
}