Some C# extensions.

Extends.cs

using System;
using System.IO;
using System.Web;
using System.Text;
using System.Collections.Generic;
using System.Collections;

namespace Raoni {
	public delegate bool Generator<T>(out T value);
	public delegate bool Enumerator<T>(T value);

	public static class Extends {
		//String
		public static string toMD5(this String text) {
			MD5 md5 = MD5.Create();
			byte[] hash = md5.ComputeHash(System.Text.Encoding.ASCII.GetBytes(text));

			StringBuilder sb = new StringBuilder();
			for(int i = 0; i < hash.Length; i++)
				sb.Append(hash[i].ToString("x2"));

			return sb.ToString();
		}
		public static bool isEmpty(this string s) {
			return s == null || s == "";
		}
		public static bool isFilled(this string s) {
			return !s.isEmpty();
		}
		public static string truncate(this string s, int l, string e = "...", bool isHTML = false, bool closeTags = true) {
			int i = 0;
			Stack<string> tags = new Stack<string>();
			if(isHTML) {
				foreach(Match o in Regex.Matches(s, "<[^>]+>([^<]*)")) {
					if(o.Index - i >= l)
						break;
					string t = o.Value.Substring(1, o.Value.IndexOfAny(new char[] { ' ', '\t', '\n', '\r', '\0', '\x0b', '>' }) - 1);
					if(t.Substring(0, 1) != "/")
						tags.Push(t);
					else if(tags.Peek() == t.Substring(1))
						tags.Pop();
					i += o.Groups[1].Index - o.Index;
				}
			}
			return s.Substring(0, l = Math.Min(s.Length, l + i)) + (closeTags && tags.Count > 0 ? "</" + tags.join("></") + ">" : "") + (s.Length > l ? e : "");
		}
		public static string[] Split(this String s, string separator) {
			return s.Split(new string[] { separator }, StringSplitOptions.None);
		}
		public static int toInt(this string s) {
			int o;
			int.TryParse(s, out o);
			return o;
		}
		public static double toNumber(this string s, string decimalSeparator = "", double def = 0) {
			string dec = decimalSeparator == "" ? (s.LastIndexOf(",") > -1 ? "," : s.LastIndexOf(".") > -1 ? "." : ",") : decimalSeparator;

			NumberFormatInfo i = new NumberFormatInfo();
			i.NumberDecimalSeparator = dec;
			i.NumberGroupSeparator = dec == "." ? "," : ".";
			s.Replace(i.NumberGroupSeparator, "");

			double o;
			return double.TryParse(s, NumberStyles.Any, i, out o) ? o : def;
		}
		public static string toURLFile(this String s) {
			return Regex.Replace(Regex.Replace(s.removeAccents(), "[^a-zA-Z0-9_]", " ").Trim(), "\\s+", "-").ToLowerInvariant();
		}
		public static string mask(this String s, string mask) {
			string h = "", r = "";
			char[] ss = s.ToCharArray();
			for(int l = mask.Length, j = 0, i = 0; i < l; i++) {
				if(mask[i] != '#') {
					if(mask[i] == '\\') {
						h += mask[++i];
						continue;
					}
					h += mask[i];
					if(i + 1 == l) {
						r += ss[j - 1] + h;
						h = "";
					};
				}
				else {
					if(ss.Length <= j) {
						h = "";
						break;
					}
					r += h + ss[j];
					h = "";
					++j;
				}
			}
			return r + h;
		}
		public static string toJS(this String s, bool quote = true, string quoteCharacter = "'") {
			string p;
			return (p = quote ? quoteCharacter : "") + Regex.Replace(s.Replace("\\", "\\\\").Replace(quoteCharacter, "\\" + quoteCharacter), "\r\n|\n\r|\r|\n", "\\n") + p;
		}
		public static string toSqlSearch(this String s) {
			Dictionary<string, string> c = new Dictionary<string, string>(){
				{"%", "\\%"},
				{"_", "\\_"},
				{"\"", "\"\""}
			};
			foreach(string i in c.Keys)
				s = s.Replace(i, c[i]);
			return s;
		}
		public static string toForm(this String s, bool br = false) {
			return br ? Regex.Replace(s.Trim().toXML(), "\r\n|\n\r|\r", "<br>") : s.toXML();
		}
		public static string toEmail(this String s) {
			StringBuilder r = new StringBuilder(s.Length * 2);
			for(int i = -1, l = s.Length; ++i < l; ) {
				ulong t = 0;
				foreach(byte c in ASCIIEncoding.Unicode.GetBytes(s.Substring(i, 1)))
					t += c;
				r.Append("&#x" + t.ToString("x", CultureInfo.InvariantCulture) + ";");
			}
			return r.ToString();
		}
		public static string toDisplay(this String s, bool strip = false) {
			s = Regex.Replace(s.Trim(), "\r\n|\n\r|\r|\n", "<br>");
			return strip ? s.stripTags() : s;
		}
		public static string stripTags(this String s) {
			return Regex.Replace(s, "<\\/?[^>]+>", "");
		}
		public static string toRegExp(this String s) {
			return Regex.Escape(s);
		}
		public static string toXML(this String s) {
			Dictionary<string, int> map = new Dictionary<string, int>(){ 
				{"'", 39},
				{"\"", 34}, 
				{"<", 60}, 
				{">", 62}, 
				{"&", 38}, 
				{"\a", 07}
			};
			return Regex.Replace(s, "[" + map.Keys.join("") + "]", o => "&#" + map[o.Value] + ";");
		}
		public static string toHTML(this String s) {
			return HttpUtility.HtmlEncode(s);
		}
		public static string removeAccents(this String s) {
			string normalized = s.Normalize(NormalizationForm.FormKD);
			Encoding removal = Encoding.GetEncoding(Encoding.ASCII.CodePage, new EncoderReplacementFallback(""), new DecoderReplacementFallback(""));
			return Encoding.ASCII.GetString(removal.GetBytes(normalized));
		}
		public static ulong parseInt(this String n, int b = 0, string c = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ") {
			ulong s = 0;
			int l = n.Length, i = 0;
			if(b == 0)
				b = c.Length;

			if(b > c.Length || b < 2)
				throw new ArgumentException("Invalid arguments");
			while(l-- > 0)
				s += (ulong)c.IndexOf(n.Substring(i++, 1), StringComparison.Ordinal) * (ulong)Math.Pow(b, l);
			return s;
		}
		//IEnumerable<T>
		public static string join<T>(this IEnumerable<T> list, object separator) {
			StringBuilder s = new StringBuilder();
			using(IEnumerator<T> o = list.GetEnumerator()) {
				if(o.MoveNext())
					for(s.Append(o.Current); o.MoveNext(); s.Append(separator.ToString() + o.Current + ""))
						;
				return s.ToString();
			}
		}
		//Boolean
		public static int toInt(this bool o) {
			return o ? 1 : 0;
		}
		//Stream
		public static string toMD5(this Stream file) {
			MD5 md5 = MD5.Create();
			byte[] retVal = md5.ComputeHash(file);

			StringBuilder sb = new StringBuilder();
			for(int i = 0; i < retVal.Length; i++)
				sb.Append(retVal[i].ToString("x2"));

			return sb.ToString();
		}
		public static void WriteTo(this Stream source, Stream target) {
			WriteTo(source, target, 1024);
		}
		public static void WriteTo(this Stream source, Stream target, int bufferLength) {
			byte[] buffer = new byte[bufferLength];
			int bytesRead = 0;
			do {
				bytesRead = source.Read(buffer, 0, buffer.Length);
				target.Write(buffer, 0, bytesRead);
			}
			while(bytesRead > 0);
		}
		//Number
		public static string toBase(this int n, int b = 0, string c = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ") {
			if(b == 0)
				b = c.Length;
			if(b > c.Length || b < 2)
				throw new ArgumentException("Invalid arguments");
			string s = "";
			while(n > 0) {
				s = c[n % b] + s;
				n = (n / b);
			}
			return s;
		}
		public static bool isNumber(this object value) {
			return value is sbyte
				|| value is byte
				|| value is short
				|| value is ushort
				|| value is int
				|| value is uint
				|| value is long
				|| value is ulong
				|| value is float
				|| value is double
				|| value is decimal;
		}
		public static string formatCurrency(this double s, int c = 2, string d = ",", string t = ".") {
			NumberFormatInfo o = new NumberFormatInfo();
			o.NumberDecimalDigits = c;
			o.NumberDecimalSeparator = d;
			o.NumberGroupSeparator = t;
			o.NumberGroupSizes = new int[] { 3 };
			o.NumberNegativePattern = 1;
			return s.ToString("n", o);
		}		
	}
}