(function($){

	$.fn.alphanumeric = function(p) { 

		p = $.extend({
			ichars: "!@#$%^&*()+=[]\\\';,/{}|\":<>?~`.- ",
			nchars: "",
			allow: "",
			once: ""
		  }, p);	

		return this.each
			(
				function() 
				{

					if (p.nocaps) p.nchars += "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
					if (p.allcaps) p.nchars += "abcdefghijklmnopqrstuvwxyz";
					
					s = p.allow.split('');
					for ( i=0;i<s.length;i++) if (p.ichars.indexOf(s[i]) != -1) s[i] = "\\" + s[i];
					p.allow = s.join('|');
					
					// construct list of 'forbidden' characters
					var reg = new RegExp(p.allow,'gi'); // regexp for the list of allowed chars
					var ch = p.ichars + p.nchars;		// list of forbidden chars
					ch = ch.replace(reg,'');			// remove allowed chars from that list
					
					$(this).keypress
						(
							function (e)
								{
									var ch_copy = ch;
									
									var val = $(this).val();
									for ( i=0; i<p.once.length; i++) {
										if (val.indexOf(p.once.charAt(i)) != -1) {
											// input field contains this character from the 'once' list
											ch_copy = ch_copy + p.once.charAt(i);
										}
									}
								
									if (!e.charCode) k = String.fromCharCode(e.which);
										else k = String.fromCharCode(e.charCode);
										
									if (ch_copy.indexOf(k) != -1) e.preventDefault();
									if (e.ctrlKey&&k=='v') e.preventDefault();
									
								}
								
						);
						
					$(this).bind('contextmenu',function () {return false});
									
				}
			);

	};

	$.fn.numeric = function(p) {
	
		var az = "abcdefghijklmnopqrstuvwxyz";
		az += az.toUpperCase();

		p = $.extend({
			nchars: az
		  }, p);	
		  	
		return this.each (function()
			{
				$(this).alphanumeric(p);
			}
		);
			
	};
	
	$.fn.alpha = function(p) {

		var nm = "1234567890";

		p = $.extend({
			nchars: nm
		  }, p);	

		return this.each (function()
			{
				$(this).alphanumeric(p);
			}
		);
			
	};	

})(jQuery);