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

   1 using System.Globalization;
   2
   3 namespace System.Windows
   4 {
   5         /// <summary>
   6         /// Helper class for parsing serialized data structures from the System.Windows namespace.
   7         /// </summary>
   8         internal class NumericListTokenizer
   9         {
  10                 private readonly string _str;
  11                 private readonly char _separator;
  12                 private int _position;
  13
  14                 private enum Symbol
  15                 {
  16                         Token,
  17                         Separator,
  18                         Whitspace,
  19                         EndOfLine
  20                 }
  21
  22                 public NumericListTokenizer (string str, IFormatProvider formatProvider)
  23                 {
  24                         _str = str ?? throw new ArgumentNullException (nameof(str));
  25                         _separator = GetSeparator (formatProvider ?? throw new ArgumentNullException (nameof(formatProvider)));
  26                 }
  27
  28                 public static char GetSeparator (IFormatProvider formatProvider)
  29                 {
  30                         // By convention, string representations of target classes always use ';' as a separator
  31                         // if the decimal number separator is ','. Otherwise, the separator is ','.
  32                         return NumberFormatInfo.GetInstance (formatProvider).NumberDecimalSeparator != "," ? ',' : ';';
  33                 }
  34
  35                 private Symbol GetCurrentSymbol ()
  36                 {
  37                         if (_position >= _str.Length)
  38                                 return Symbol.EndOfLine;
  39                         if (_str[_position] == _separator)
  40                                 return Symbol.Separator;
  41                         if (char.IsWhiteSpace (_str, _position))
  42                                 return Symbol.Whitspace;
  43                         return Symbol.Token;
  44                 }
  45
  46                 private void SkipAllWhitespaces ()
  47                 {
  48                         while (GetCurrentSymbol () == Symbol.Whitspace)
  49                         {
  50                                 _position++;
  51                         }
  52                 }
  53
  54                 private void SkipNextDelimeter ()
  55                 {
  56                         SkipAllWhitespaces ();
  57                         switch (GetCurrentSymbol ())
  58                         {
  59                                 case Symbol.Token:
  60                                         return;
  61                                 case Symbol.Separator:
  62                                         _position++;
  63                                         SkipAllWhitespaces ();
  64                                         return;
  65                                 default:
  66                                         throw new InvalidOperationException ("Separator not found");
  67                         }
  68                 }
  69
  70                 public bool HasNoMoreTokens ()
  71                 {
  72                         SkipAllWhitespaces ();
  73                         return GetCurrentSymbol () == Symbol.EndOfLine;
  74                 }
  75
  76                 public string GetNextToken ()
  77                 {
  78                         var length = 0;
  79                         if (_position == 0)
  80                         {
  81                                 SkipAllWhitespaces ();
  82                         }
  83                         else
  84                         {
  85                                 SkipNextDelimeter ();
  86                         }
  87
  88                         while (GetCurrentSymbol () == Symbol.Token)
  89                         {
  90                                 _position++;
  91                                 length++;
  92                         }
  93
  94                         if (length == 0)
  95                         {
  96                                 throw new InvalidOperationException ("Next token not found");
  97                         }
  98
  99                         return _str.Substring (_position - length, length);
 100                 }
 101         }
 102 }