/*
 * String utilities
 *
 */

function replaceQuot(val) {
	var re = /\"/g;
	return val.replace(re,""");
}

function replaceSlash(val) {
	var re = /\//g;
	return val.replace(re,"\\/");
}

function replaceAll(val,from,to) {
	from = replaceSlash(from);
	var re = eval("/"+from+"/g");
	return val.replace(re,to);
}

function urlEncode(txt)
{
	// The Javascript escape and unescape functions do not correspond
	// with what browsers actually do...
	var SAFECHARS = "0123456789" +					// Numeric
					"ABCDEFGHIJKLMNOPQRSTUVWXYZ" +	// Alphabetic
					"abcdefghijklmnopqrstuvwxyz" +
					"-_.!~*'()";					// RFC2396 Mark characters
	var HEX = "0123456789ABCDEF";

	var plaintext = txt;
	var encoded = "";
	for (var i = 0; i < plaintext.length; i++ ) {
		var ch = plaintext.charAt(i);
	    if (ch == " ") {
		    encoded += "+";				// x-www-urlencoded, rather than %20
		} else if (SAFECHARS.indexOf(ch) != -1) {
		    encoded += ch;
		} else {
		    var charCode = ch.charCodeAt(0);
			if (charCode > 255) {
			    alert( "Unicode Character '" 
                        + ch 
                        + "' cannot be encoded using standard URL encoding.\n" +
				          "(URL encoding only supports 8-bit characters.)\n" +
						  "A space (+) will be substituted." );
				encoded += "+";
			} else {
				encoded += "%";
				encoded += HEX.charAt((charCode >> 4) & 0xF);
				encoded += HEX.charAt(charCode & 0xF);
			}
		}
	} // for

	return encoded;
};

function urlDecode(txt)
{
   // Replace + with ' '
   // Replace %xx with equivalent character
   // Put [ERROR] in output if %xx is invalid.
   var HEXCHARS = "0123456789ABCDEFabcdef"; 
   var encoded = txt;
   var plaintext = "";
   var i = 0;
   while (i < encoded.length) {
       var ch = encoded.charAt(i);
	   if (ch == "+") {
	       plaintext += " ";
		   i++;
	   } else if (ch == "%") {
			if (i < (encoded.length-2) 
					&& HEXCHARS.indexOf(encoded.charAt(i+1)) != -1 
					&& HEXCHARS.indexOf(encoded.charAt(i+2)) != -1 ) {
				plaintext += unescape( encoded.substr(i,3) );
				i += 3;
			} else {
				alert( 'Bad escape combination near ...' + encoded.substr(i) );
				plaintext += "%[ERROR]";
				i++;
			}
		} else {
		   plaintext += ch;
		   i++;
		}
	} // while
   return plaintext;
};


/*
 * DOM utilities
 *
 */

function showLayer(id)
{
	document.getElementById(id).style.display = "block";
}

function hideLayer(id)
{
	document.getElementById(id).style.display = "none";
}

function toggleDisplay(id)
{
	var elem = document.getElementById(id);
	
	if (elem.style.display == 'block') 
		elem.style.display = 'none';
	else
		elem.style.display = 'block';
};

function getElementsByClass( searchClass, domNode, tagName) {
	if (domNode == null) domNode = document;
	if (tagName == null) tagName = '*';
	var el = new Array();
	var tags = domNode.getElementsByTagName(tagName);
	var tcl = " "+searchClass+" ";
	for(i=0,j=0; i<tags.length; i++) {
		var test = " " + tags[i].className + " ";
		if (test.indexOf(tcl) != -1)
			el[j++] = tags[i];
	}
	return el;
};