/// <summary> pattern for a decimal integer.
/// It starts with a non-zero digit and followed by 0 or more digits.
/// </summary>
/// <returns> the Pattern object.
/// </returns>
public static Pattern IsDecInteger()
{
return(InRange('1', '9').Seq(Many(CharPredicates.IsDigit())));
}
/// <summary> Recognizes a decimal point and 1 or more digits after it.</summary>
/// <returns> the Pattern object.
/// </returns>
public static Pattern IsDecimalR()
{
return(IsChar('.').Seq(Many(1, CharPredicates.IsDigit())));
}
/// <summary> pattern for an integer. ([0-9]+) </summary>
/// <returns> the Pattern object.
/// </returns>
public static Pattern IsInteger()
{
return(Many(1, CharPredicates.IsDigit()));
}
/// <summary> a decimal number that has at least one number before the decimal point.
/// the decimal point and the numbers to the right are optional.
/// 0, 11., 2.3 are all good candidates. While .1, . are not.
/// </summary>
/// <returns> the Pattern object.
/// </returns>
public static Pattern IsDecimalL()
{
CharPredicate cp = CharPredicates.IsDigit();
return(Many(1, cp).Seq(IsChar('.').Seq(Many(cp)).Optional()));
}
