Imported Upstream version 5.8.0.22

Former-commit-id: df344e34b07851d296efb3e6604c8db42b6f7aa3

mcs/class/WindowsBase/System.Windows/NumericListTokenizer.cs

@@ -0,0 +1,102 @@
+using System.Globalization;
+
+namespace System.Windows
+{
+	/// <summary>
+	/// Helper class for parsing serialized data structures from the System.Windows namespace.
+	/// </summary>
+	internal class NumericListTokenizer
+	{
+		private readonly string _str;
+		private readonly char _separator;
+		private int _position;
+
+		private enum Symbol
+		{
+			Token,
+			Separator,
+			Whitspace,
+			EndOfLine
+		}
+
+		public NumericListTokenizer (string str, IFormatProvider formatProvider)
+		{
+			_str = str ?? throw new ArgumentNullException (nameof(str));
+			_separator = GetSeparator (formatProvider ?? throw new ArgumentNullException (nameof(formatProvider)));
+		}
+
+		public static char GetSeparator (IFormatProvider formatProvider)
+		{
+			// By convention, string representations of target classes always use ';' as a separator
+			// if the decimal number separator is ','. Otherwise, the separator is ','.
+			return NumberFormatInfo.GetInstance (formatProvider).NumberDecimalSeparator != "," ? ',' : ';';
+		}
+
+		private Symbol GetCurrentSymbol ()
+		{
+			if (_position >= _str.Length)
+				return Symbol.EndOfLine;
+			if (_str[_position] == _separator)
+				return Symbol.Separator;
+			if (char.IsWhiteSpace (_str, _position))
+				return Symbol.Whitspace;
+			return Symbol.Token;
+		}
+
+		private void SkipAllWhitespaces ()
+		{
+			while (GetCurrentSymbol () == Symbol.Whitspace)
+			{
+				_position++;
+			}
+		}
+
+		private void SkipNextDelimeter ()
+		{
+			SkipAllWhitespaces ();
+			switch (GetCurrentSymbol ())
+			{
+				case Symbol.Token:
+					return;
+				case Symbol.Separator:
+					_position++;
+					SkipAllWhitespaces ();
+					return;
+				default:
+					throw new InvalidOperationException ("Separator not found");
+			}
+		}
+
+		public bool HasNoMoreTokens ()
+		{
+			SkipAllWhitespaces ();
+			return GetCurrentSymbol () == Symbol.EndOfLine;
+		}
+
+		public string GetNextToken ()
+		{
+			var length = 0;
+			if (_position == 0)
+			{
+				SkipAllWhitespaces ();
+			}
+			else
+			{
+				SkipNextDelimeter ();
+			}
+
+			while (GetCurrentSymbol () == Symbol.Token)
+			{
+				_position++;
+				length++;
+			}
+
+			if (length == 0)
+			{
+				throw new InvalidOperationException ("Next token not found");
+			}
+
+			return _str.Substring (_position - length, length);
+		}
+	}
+}