Replace Unicode (Tamil) string using Regular Expression C#

Question

I'm implementing for Lexical parsing in Tamil Language. I need to replace a Text Element value by following condition

        string[] ugaramStrings = { "கு", "சு", "டு", "து", "பு", "று" };
        string[] tamilvowels =
            {
                "அ",// "\u0b85"
                "ஆ",//"\u0b86"
                "இ",//"\u0b87"
                "ஈ",//"\u0b88"
                "உ",//"\u0b89"
                "ஊ",//"\u0b8A"
                "எ",// "\u0b8E"
                "ஏ",//"\u0b8F"
                "ஐ",//"\u0b90"
                "ஒ",//"\u0b92"
                "ஓ",//"\u0b93"
                "ஔ"//"\u0b94"
            };

if any word having element from ugaramStrings and tamil vowel element by consecutive. Is need to be replace ugaram string and return the value.

for eg.அமர்ந்*துஇ*னிது replaced as அமர்ந்*இ*னிது. i.e துஇ=>இ

I've done it by checking next string element using TextElementEnumerator Class. Is it any possiblity is avail so that replace it by using RegularExpression

Answer 1

Try this:

string[] ugaramStrings = { "கு", "சு", "டு", "து", "பு", "று" };
string[] tamilvowels =
{
    "அ",// "\u0b85"
    "ஆ",//"\u0b86"
    "இ",//"\u0b87"
    "ஈ",//"\u0b88"
    "உ",//"\u0b89"
    "ஊ",//"\u0b8A"
    "எ",// "\u0b8E"
    "ஏ",//"\u0b8F"
    "ஐ",//"\u0b90"
    "ஒ",//"\u0b92"
    "ஓ",//"\u0b93"
    "ஔ"//"\u0b94"
};

var rxTemp = "(" +
    string.Join("|", ugaramStrings) + ")(" +
    string.Join("|", tamilvowels) + ")";

var rx = new Regex(rxTemp);

string str = "அமர்ந்*துஇ*னிது";

// This will contain all the matches
var matches = new List<Match>();

string str2 = rx.Replace(str, match => {
    matches.Add(match);
    // Group[1] will contain the ugaram letter, 
    // Group[2] will contain the tamil vowel
    return match.Groups[2].Value;
});

it seems to work correctly. The str2 will contain the replaced string while matches will contain all the matches

Note that ugaram characters are composed characters, for example, so each ugaram "character" uses two C# chars.

For example கு is 'க' + 'ு'.

This is illegal:

char ch = 'இ';

This is legal:

string str = "இ"; // str.Length == 2

For this reason you can't simply [குசுடுதுபுறு] but you have to (கு|சு|டு|து|பு|று).