(MahAppsGH-3665) Fix NumericUpDown decimal places replace with 0 in p…

…ersian culture

We need to use a dynamic Regex for the number input instead a static one. So we must look for the NumberFormat.NumberDecimalSeparator and NumberFormat.NumberGroupSeparator and build a new Regex if the Culture was changed.

Closes MahApps#3665

src/MahApps.Metro/Controls/NumericUpDown.cs

@@ -138,6 +138,7 @@ public class NumericUpDown : Control
                     if (e.NewValue != e.OldValue)
                     {
                         var numUpDown = (NumericUpDown)o;
+                        numUpDown.regexNumber = null;
                         numUpDown.OnValueChanged(numUpDown.Value, numUpDown.Value);
                     }
                 }));
@@ -187,7 +188,8 @@ private static void InterceptManualEnterChangedCallback(DependencyObject depende
         }
 
         private static readonly Regex RegexStringFormatHexadecimal = new Regex(@"^(?<complexHEX>.*{\d:X\d+}.*)?(?<simpleHEX>X\d+)?$", RegexOptions.Compiled);
-        private static readonly Regex RegexNumber = new Regex(@"[-+]?(?<![0-9][.,])[.,]?[0-9]+(?:[.,\s][0-9]+)*[.,]?[0-9]?(?:[eE][-+]?[0-9]+)?(?!\.[0-9])", RegexOptions.Compiled);
+        private const string RawRegexNumberString = @"[-+]?(?<![0-9][<DecimalSeparator><GroupSeparator>])[<DecimalSeparator><GroupSeparator>]?[0-9]+(?:[<DecimalSeparator><GroupSeparator>\s][0-9]+)*[<DecimalSeparator><GroupSeparator>]?[0-9]?(?:[eE][-+]?[0-9]+)?(?!\.[0-9])";
+        private Regex regexNumber = null;
         private static readonly Regex RegexHexadecimal = new Regex(@"^([a-fA-F0-9]{1,2}\s?)+$", RegexOptions.Compiled);
         private static readonly Regex RegexStringFormat = new Regex(@"\{0\s*(:(?<format>.*))?\}", RegexOptions.Compiled);
 
@@ -1282,7 +1284,7 @@ private bool ValidateText(string text, out double convertedValue)
                         || this.ParsingNumberStyle.HasFlag(NumberStyles.AllowHexSpecifier)
                         || this.ParsingNumberStyle == NumberStyles.HexNumber;
 
-            var number = TryGetNumberFromText(text, isHex);
+            var number = this.TryGetNumberFromText(text, isHex);
 
             // If we are only accepting numbers then attempt to parse as an integer.
             if (isNumeric)
@@ -1325,15 +1327,22 @@ private bool ConvertNumber(string text, out double convertedValue)
             return true;
         }
 
-        private static string TryGetNumberFromText(string text, bool isHex)
+        private string TryGetNumberFromText(string text, bool isHex)
         {
             if (isHex)
             {
                 var hexMatches = RegexHexadecimal.Matches(text);
                 return hexMatches.Count > 0 ? hexMatches[0].Value : text;
             }
 
-            var matches = RegexNumber.Matches(text);
+            if (this.regexNumber == null)
+            {
+                this.regexNumber = new Regex(RawRegexNumberString.Replace("<DecimalSeparator>", this.SpecificCultureInfo.NumberFormat.NumberDecimalSeparator)
+                                                                 .Replace("<GroupSeparator>", this.SpecificCultureInfo.NumberFormat.NumberGroupSeparator),
+                                             RegexOptions.Compiled);
+            }
+
+            var matches = this.regexNumber.Matches(text);
             return matches.Count > 0 ? matches[0].Value : text;
         }
     }

src/Mahapps.Metro.Tests/Tests/NumericUpDownTests.cs

@@ -280,6 +280,37 @@ public async Task ShouldConvertDecimalTextInput()
             Assert.Equal(0.0115d, window.TheNUD.Value);
         }
 
+        [Fact]
+        [DisplayTestMethodName]
+        public async Task ShouldConvertDecimalTextInputWithSpecialCulture()
+        {
+            await TestHost.SwitchToAppThread();
+            var window = await WindowHelpers.CreateInvisibleWindowAsync<NumericUpDownWindow>().ConfigureAwait(false);
+            await TestHost.SwitchToAppThread();
+
+            var textBox = window.TheNUD.FindChild<TextBox>(string.Empty);
+            Assert.NotNull(textBox);
+
+            window.TheNUD.NumericInputMode = NumericInput.Decimal;
+
+            window.TheNUD.Culture = CultureInfo.GetCultureInfo("fa-IR");
+
+            SetText(textBox, "42");
+            Assert.Equal(42d, window.TheNUD.Value);
+
+            SetText(textBox, "42/751");
+            Assert.Equal(42.751d, window.TheNUD.Value);
+
+            SetText(textBox, "/");
+            Assert.Equal(0d, window.TheNUD.Value);
+
+            SetText(textBox, "/9");
+            Assert.Equal(0.9d, window.TheNUD.Value);
+
+            SetText(textBox, "/0115");
+            Assert.Equal(0.0115d, window.TheNUD.Value);
+        }
+
         [Fact]
         [DisplayTestMethodName]
         public async Task ShouldConvertNumericTextInput()