protected override Variable Evaluate(ParsingScript script)
{
// 1. Get the name of the variable.
string varName = Utils.GetToken(script, Constants.NEXT_OR_END_ARRAY);
Utils.CheckNotEnd(script, Constants.CONTAINS);
// 2. Get the current value of the variable.
List <Variable> arrayIndices = Utils.GetArrayIndices(ref varName);
ParserFunction func = ParserFunction.GetFunction(varName);
Utils.CheckNotNull(varName, func);
Variable currentValue = func.GetValue(script);
// 2b. Special dealings with arrays:
Variable query = arrayIndices.Count > 0 ?
Utils.ExtractArrayElement(currentValue, arrayIndices) :
currentValue;
// 3. Get the value to be looked for.
Variable searchValue = Utils.GetItem(script);
Utils.CheckNotEnd(script, Constants.CONTAINS);
// 4. Check if the value to search for exists.
bool exists = query.Exists(searchValue, true /* notEmpty */);
script.MoveBackIf(Constants.START_GROUP);
return(new Variable(exists));
}