/// <summary>
/// Resolve a dot-notation reference to values in this object
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
public object ResolveExpressionValue(string expression)
{
if (string.IsNullOrEmpty(expression))
{
return(null);
}
//look for reserved values:
if (expression == "length")
{
return(Length);
}
if (IsArray)
{
string ndx, after = null;
if (expression.StartsWith("["))
{
int bend = expression.IndexOf("]");
if (bend == -1)
{
throw new ArgumentException("Bad resolver expression in JSON: " + expression);
}
ndx = expression.Substring(1, bend - 1);
if (!expression.EndsWith("]"))
{
if (expression.Substring(bend + 1, 1) == ".")
{
after = expression.Substring(bend + 2);
}
else
{
after = expression.Substring(bend + 1);
}
}
}
else
{
ndx = expression;
}
int pos;
object item = null;
if (Int32.TryParse(ndx, out pos))
{
if (pos > -1 && DataList.Count > pos)
{
item = DataList[pos];
}
}
//and @attrib values
else if (ndx.StartsWith("@"))
{
string attrib;
string val;
if (ParseSelectorString(ndx, out attrib, out val))
{
//cycle array
for (int i = 0; i < DataList.Count; i++)
{
if (DataList[i] is IExpressionEvaluator)
{
IExpressionEvaluator evalObj = DataList[i] as IExpressionEvaluator;
object actualVal = evalObj.ResolveExpressionValue(attrib);
if (!string.IsNullOrEmpty(val) &&
val.Equals(actualVal))
{
item = evalObj;
break;
}
}
}
}
}
if (string.IsNullOrEmpty(after))
{
return(item);
}
else if (item is IExpressionEvaluator)
{
return(((IExpressionEvaluator)item).ResolveExpressionValue(after));
}
}
else
{
string key = ExtractJSONKey(expression);
if (string.IsNullOrEmpty(key))
{
return(null);
}
if (DataDictionary.ContainsKey(key))
{
return(DataDictionary[key]);
}
else
{
int dotPos = key.IndexOf(".");
int bracketPos = key.IndexOf("[");
if (dotPos == -1 && bracketPos == -1)
{
return(null);
}
bool isDot = false;
bool isIndex = false;
if (dotPos > -1 && bracketPos > -1)
{
if (dotPos < bracketPos)
{
isDot = true;
}
else
{
isIndex = true;
}
}
else if (dotPos > -1)
{
isDot = true;
}
else if (bracketPos > -1)
{
isIndex = true;
}
if (isDot)
{
string first = key.Substring(0, dotPos);
string theRest = key.Substring(dotPos + 1);
if (DataDictionary.ContainsKey(first))
{
object val = DataDictionary[first];
if (val is IExpressionEvaluator)
{
return(((IExpressionEvaluator)val).ResolveExpressionValue(theRest));
}
else
{
return(null);
}
}
else
{
return(null);
}
}
else if (isIndex)
{
string first = key.Substring(0, bracketPos);
string theRest = key.Substring(bracketPos);
if (theRest.EndsWith("]") && theRest.StartsWith("["))
{
theRest = theRest.Substring(1, theRest.Length - 2);
}
if (DataDictionary.ContainsKey(first))
{
object val = DataDictionary[first];
if (val is IExpressionEvaluator)
{
return(((IExpressionEvaluator)val).ResolveExpressionValue(theRest));
}
else
{
return(null);
}
}
else
{
return(null);
}
}
else
{
return(null);
}
}
}
return(null);
}
