RegExHelper.cs

using System.Text.RegularExpressions;
using System.Linq;

/// <summary>
/// Helper class for handling regular expressions.
/// </summary>
public static class RegExHelper
{
    /// <summary>
    /// Finds matches in the input text based on the search text, treating each word in the search text as a separate pattern.
    /// </summary>
    /// <param name="inputText">The text to search within.</param>
    /// <param name="searchText">The text containing words to search for. Each word is treated as a separate pattern.</param>
    /// <returns>A MatchCollection containing all matches found. Returns null if the search text is null or whitespace.</returns>
    public static MatchCollection GetRegExMatches(string inputText, string searchText)
    {
        if (string.IsNullOrWhiteSpace(searchText))
        {
            return null;
        }

        var safeSearchText = string.Join("|", searchText.Split(' ').Select(word => Regex.Escape(word)));

        if (!string.IsNullOrWhiteSpace(safeSearchText))
        {
            return Regex.Matches(inputText, safeSearchText, RegexOptions.IgnoreCase);
        }

        return null;
    }
}