//initializes a new instance of the StringBuilder class and appends a string if passed.
StringBuilder = function(input) {
var _items = new Array();
var _length = 0;
var _RegExp = /{\d+}|{\d+:[^\r\n{}]+}/g;
//appends a string at the end, and returns the StringBuilder instance.
this.append = function(input) {
_items.push(input);
_length += input.length;
return this;
};
//appends a string in a new line and returns the StringBuilder instance.
this.appendLine = function(input) {
return this.append("\n").append(input);
};
//Reinitializes the StringBuilder instance before returning it.
this.clear = function() {
_items = new Array();
_length = 0;
return this;
};
this.toString = function(separator) {
return (separator != null) ? _items.join(separator) : _items.join('');
};
//Appends a string using Composite Formatting and returns the StringBuilder instance.
this.appendFormat = function() {
//the first argument is the composite string
var Result = arguments[0];
//looping through Result
//replacing each {n} with arguments[n+1]
var RegExpResult = null;
while ((RegExpResult = _RegExp.exec(Result)) != null) {
//RegExp.exec doesn't return a string,
//type conversion is necessary
RegExpResult = RegExpResult.toString();
//extracting the index,
//and the formatting string,
var ColonsPosition = RegExpResult.indexOf(":");
var paramIndex = -1;
var paramFormat = '';
if (ColonsPosition != -1) {
paramIndex = Number(RegExpResult.substr(1, ColonsPosition - 1));
paramFormat = RegExpResult.substr(ColonsPosition + 1, RegExpResult.length - 2 - ColonsPosition);
}
else {
paramIndex = Number(RegExpResult.substr(1, RegExpResult.length - 2));
}
//replacing the format item in Result string
paramIndex++;
var Replacement = (ColonsPosition != -1) ? arguments[paramIndex].toString(paramFormat) : arguments[paramIndex].toString();
Result = Result.replace(RegExpResult, Replacement);
//g Flag makes RegExp remember the last position,
//we're updating it because directly we're modifying
//the string we're using the perform the search
_RegExp.lastIndex += Replacement.length - RegExpResult.length;
};
//appending the formatted string to the StringBuilder
return this.append(Result);
};
};
