Path

// System.IO.Path — System.Core (decompiled from Larva HIR)

into namespace System.IO
{
	/// Paths as text: '/' and '\' both separate folders.
	public static class Path
	{
		IsSeparator(u8 c) : bool => c == 47 || c == 92;

		/// Where the file name starts.
		NameStart(str path) : i32
		{
			i32 i = path.Length - 1;
			loop (i >= 0 && !IsSeparator(path[i]) && path[i] != 58)
				i--;
			return i + 1;
		}

		public:
			Combine(str first, str second) : str
			{
				if (first.Length == 0 || second.Length > 0 && (IsSeparator(second[0]) || second.Length > 1 && second[1] == 58))
					return second;
				return IsSeparator(first[first.Length - 1]) ? first + second : first + "/" + second;
			}

			Combine(str first, str second, str third) : str => Combine(Combine(first, second), third);

			GetFileName(str path) : str => path.Substring(NameStart(path));

			/// The extension with its point ("" when there is none).
			GetExtension(str path) : str
			{
				str name = GetFileName(path);
				i32 dot = name.LastIndexOf(46);
				return dot <= 0 ? "" : name.Substring(dot);
			}

			GetFileNameWithoutExtension(str path) : str
			{
				str name = GetFileName(path);
				i32 dot = name.LastIndexOf(46);
				return dot <= 0 ? name : name.Substring(0, dot);
			}

			/// The folder part ("" when there is none).
			GetDirectoryName(str path) : str
			{
				i32 start = NameStart(path);
				if (start == 0)
					return "";
				return start == 1 ? path.Substring(0, 1) : path.Substring(0, start - 1);
			}

			ChangeExtension(str path, str extension) : str
			{
				i32 start = NameStart(path);
				i32 dot = GetFileName(path).LastIndexOf(46);
				str stem = dot <= 0 ? path : path.Substring(0, start + dot);
				if (extension.Length == 0)
					return stem;
				return extension[0] == 46 ? stem + extension : stem + "." + extension;
			}

			HasExtension(str path) : bool => GetExtension(path).Length > 0;

			u8 DirectorySeparatorChar
			{
				get => 47;
			}
	}
}