using System.Collections.Concurrent;

using System.Text.RegularExpressions;

using System;

namespace Simple.Data.Extensions

{

public static class HomogenizeEx

{

private static readonly ConcurrentDictionary<string, string> Cache

= new ConcurrentDictionary<string, string>(StringComparer.InvariantCultureIgnoreCase);

private static Regex _homogenizeRegex = new Regex("[^a-z0-9]");

/// <summary>

/// Downshift a string and remove all non-alphanumeric characters.

/// </summary>

/// <param name="source">The original string.</param>

/// <returns>The modified string.</returns>

public static string Homogenize(this string source)

{

return source == null ? null : Cache.GetOrAdd(source, HomogenizeImpl);

}

private static string HomogenizeImpl(string source)

{

return string.Intern(_homogenizeRegex.Replace(source.ToLowerInvariant(), string.Empty));

}

/// <summary>

/// Sets the regular expression to be used for homogenizing object names.

/// </summary>

/// <param name="regex">A regular expression matching all non-comparing characters. The default is &quot;[^a-z0-9]&quot;.</param>

/// <remarks>Homogenized strings are always forced to lower-case.</remarks>

public static void SetRegularExpression(Regex regex)

{

_homogenizeRegex = regex;

}

}

}