在XAML转换器中简化电话号码上的正则表达式

Question

C＃正则表达式

这是一个使用Regex的WPF的简单转换器，以显示带有电话号码掩码的一致TextBox：

public class MyStringToPhoneConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    if (value == null)
        return string.Format("(   )    -    ");

    //remove formating...returns a string of digits.
    string phoneNo = value.ToString().Replace("(", string.Empty).Replace(")", string.Empty).Replace(" ", string.Empty).Replace("-", string.Empty);

    // All displayed formating in WPF depends on the control FontSytle. Use a fixed-width,  monospaced, font with no kerning.
    // Examples: Consolas, Courier New, Lucida Console, MS Gothic
    switch (phoneNo.Length)
    {
        case 0:
            return string.Format("(   )    -   ");
        case 1:
            return Regex.Replace(phoneNo, @"(\d{1})", "($1  )    -    ");
        case 2:
            return Regex.Replace(phoneNo, @"(\d{2})", "($1 )    -    ");
        case 3:
            return Regex.Replace(phoneNo, @"(\d{3})", "($1)    -    ");
        case 4:
            return Regex.Replace(phoneNo, @"(\d{3})(\d{1})", "($1) $2  -    ");
        case 5:
            return Regex.Replace(phoneNo, @"(\d{3})(\d{2})", "($1) $2 -    ");
        case 6:
            return Regex.Replace(phoneNo, @"(\d{3})(\d{3})", "($1) $2-    ");
        case 7:
            return Regex.Replace(phoneNo, @"(\d{3})(\d{3})(\d{1})", "($1) $2-$3   ");
        case 8:
            return Regex.Replace(phoneNo, @"(\d{3})(\d{3})(\d{2})", "($1) $2-$3  ");
        case 9:
            return Regex.Replace(phoneNo, @"(\d{3})(\d{3})(\d{3})", "($1) $2-$3 ");
        case 10:
            return Regex.Replace(phoneNo, @"(\d{3})(\d{3})(\d{4})", "($1) $2-$3");
        case 11:
            return Regex.Replace(phoneNo, @"(\d{1})(\d{3})(\d{3})(\d{4})", "$1-$2-$3-$4");
        default:
            return phoneNo;
    }

}

public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
    return value;
}

}

这似乎非常重复，必须为每个字符串长度编写不同的字符串和正则表达式。

是否有一个或两个正则表达式可以使用一致的输出格式处理不同的字符串长度？ （我不太关心11位数字：））

TIA

Answer 1

下面是尝试摆脱多个Regex模板和替换字符串的尝试。 我想出的Regex有点复杂，更换程序需要自定义评估程序。 无论如何，它似乎达到了预期的目标。

一些评论：

• (?<!\\d.*) -确保匹配以第一个数字开头
• ((?=\\d{11})\\d{1})? -当提供所有11位数字时，与第一组（1位数字）匹配
• (\\d{1,3}) -允许部分填充的组
• |^(?!.*\\d) -找不到数字时仍然匹配

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    //remove formating...returns a string of digits.
    string phoneNo = Regex.Replace(value?.ToString() ?? string.Empty, @"[\(\)\- ]", string.Empty);

    return Regex.Replace(phoneNo, @"(?<!\d.*)((?=\d{11})\d{1})?(\d{1,3})(\d{1,3})?(\d{1,4})?|^(?!.*\d)", m =>
    {
        var gr1 = m.Groups[1].Value;
        var gr2 = m.Groups[2].Value.PadRight(3);
        var gr3 = m.Groups[3].Value.PadRight(3);
        var gr4 = m.Groups[4].Value.PadRight(4);

        return m.Groups[1].Success
            ? $"{gr1}-{gr2}-{gr3}-{gr4}"
            : $"({gr2}) {gr3}-{gr4}";
    });
}