/// <summary>
/// This method takes a Chartypes value and returns the corresponding regex symbol.</summary>
/// <param name="chartype"> The type of the character as specified by the enum Chartypes </param>
public static string GetRegexPart(Chartypes chartype)
{
string res = map.GetValueOrDefault(chartype);
if (string.IsNullOrEmpty(res))
{
throw new Exception();
}
return(res);
}
/// <summary>
/// This method takes a string/word and reverse builds the corresponing regex.
/// It is case sensitive. It converts each character into a
/// RegexCharacterGenerator.Chartypes value before the conversion.</summary>
/// <param name="inputString"> The input string</param>
/// <seealso cref="RegexCharacterGenerator">
/// Contains a public member enum used in categorizing the character type </seealso>
/// <seealso cref="System.Text.RegularExpressions.Regex">
/// The resultant output string is meant to be used in the Regex class.</seealso>
public static string GenerateRegex(string inputString)
{
// Stores the type of each characher in the input
List <Chartypes> list = new List <Chartypes>();
// Stores the resulting regexp returned by the function
string regex;
// Alot of string manipulation will be done, so use SB class
StringBuilder stringBuilder = new StringBuilder();
// Go through each character in the input and categorize it based on it type given by
// RegexCharacterGenerator.Chartypes
foreach (char c in inputString)
{
list.Add(RegexCharacterGenerator.GetTypeFor(c));
}
// If there are no charcters, return empty regexp
if (list.Count == 0)
{
regex = "//";
return(regex);
}
// If its just one characted, there is no need to perform algorithm just get the regex for the charater
if (list.Count == 1)
{
var result = RegexCharacterGenerator.GetRegexPart(list[0]);
RegexCharacterGenerator.CompleteRegex(ref result);
return(result);
}
int counter = 1;
Chartypes last = list[0];
list.RemoveAt(0);
foreach (Chartypes ct in list)
{
// if the last type is the same as current type
if (last == ct)
{
// increase counter to show the
counter++;
}
else
{
if (last != Chartypes.none)
{
stringBuilder.Append(RegexCharacterGenerator.GetRegexPart(last));
if (counter > 1)
{
stringBuilder.Append(RegexCharacterGenerator.GetRegexCounter(counter));
}
}
counter = 1;
}
last = ct;
}
if (counter > 0)
{
stringBuilder.Append(RegexCharacterGenerator.GetRegexPart(last));
stringBuilder.Append(RegexCharacterGenerator.GetRegexCounter(counter));
}
RegexCharacterGenerator.CompleteRegex(ref stringBuilder);
regex = stringBuilder.ToString();
return(regex);
}
