/// <summary>
/// Evaluate a single expression
/// </summary>
/// <param name="item">The current item</param>
/// <param name="exp">The expression to evaluate</param>
/// <returns>The outcome of the expression</returns>
public static bool EvaluateSingleExpression(Context context, string exp)
{
// Clean the expression
exp = exp.Trim();
// substitute tokens
exp = Parser.PerformSubstitution(context, exp);
// Parse elements
string[] elms = Parser.ParseFirstLevelGroups(exp, Constants.SubcommandEnter, Constants.SubcommandExit);
// Validate the expression
if (elms.Length != 1 && elms.Length != 2 && elms.Length != 3 && elms.Length != 5 && elms.Length != 7)
throw new ExpressionException("Malformed expression");
// a single element in the expression should be parsable true or false
if (elms.Length == 1)
{
var value = false;
if (Parser.TryParseBoolean(elms[0], out value))
return value;
else
throw new ExpressionException("Could not parse boolean value '" + elms[0] + "'");
}
// 2 elements means a function
if (elms.Length == 2)
{
switch (elms[0])
{
case "isempty":
return string.IsNullOrEmpty(elms[1]);
case "not":
return !EvaluateExpression(context, elms[1]);
case "isbound":
return context.CommandHandler.CoreCommands.ContainsKey(elms[1]) || context.CommandHandler.CustomCommands.ContainsKey(elms[1]);
default:
throw new ExpressionException("Unknown function " + elms[0]);
}
}
string op = elms[1];
if ((op != "<") && (op != ">") && (op != "=") && (op != "!=") && (op != "<=") && (op != ">=") && (op != "[") && (op != "]") && (op != "?") && (op != "!?"))
throw new ExpressionException("Invalid operator " + op);
// substitute fields and attributes and pull out casting operator and flags
string type = "string";
bool ignoreCase = false;
bool ignoreDecimal = false;
bool round = false;
bool ceil = false;
bool floor = false;
for (int i = 0; i < elms.Length; i++)
{
if (elms[i].StartsWith("@@"))
{
var inspector = new ItemInspector(context.CurrentItem);
var attr = inspector.GetItemAttribute(elms[i]);
if (attr == null)
throw new ExpressionException("Unknown attribute " + elms[i]);
elms[i] = attr;
}
else if (elms[i].StartsWith("@"))
{
elms[i] = context.CurrentItem[elms[i].Substring(1)];
}
else
{
if (elms[i] == "as")
{
if (elms.Length >= i + 2)
type = elms[i + 1];
else
throw new ExpressionException("Missing the cast type");
}
else if (elms[i] == "with")
{
if (elms.Length < i + 2)
throw new ExpressionException("Missing flags");
switch (elms[i + 1])
{
case "ignorecase": ignoreCase = true; break;
case "ignoredecimal": ignoreDecimal = true; break;
case "round": round = true; break;
case "ceiling": ceil = true; break;
case "floor": floor = true; break;
default:
throw new ExpressionException("Unknown flag " + elms[i + 1]);
}
}
}
}
string val1 = elms[0];
string val2 = elms[2];
// Do we need to convert the strings?
switch (type)
{
case "string":
if (ignoreCase)
{
val1 = val1.ToLower();
val2 = val2.ToLower();
}
// Now do the comparison
switch (op)
{
case "=":
return val1 == val2;
case "<":
return string.Compare(val1, val2) < 0;
case ">":
return string.Compare(val1, val2) > 0;
case "!=":
return val1 != val2;
case "<=":
return string.Compare(val1, val2) <= 0;
case ">=":
return string.Compare(val1, val2) >= 0;
case "[":
return val1.StartsWith(val2);
case "]":
return val1.EndsWith(val2);
case "?":
return val1.Contains(val2);
case "!?":
return !val1.Contains(val2);
}
break;
case "number":
if (val1.Length == 0 || val2.Length == 0)
return false;
double a = 0;
double b = 0;
if (!double.TryParse(val1, out a))
throw new ExpressionException(string.Format("{0} is not a number", val1));
if (!double.TryParse(val2, out b))
throw new ExpressionException(string.Format("{0} is not a number", val2));
if (ignoreDecimal)
{
a = Math.Truncate(a);
b = Math.Truncate(b);
}
if (ceil)
{
a = Math.Ceiling(a);
b = Math.Ceiling(b);
}
if (floor)
{
a = Math.Floor(a);
b = Math.Floor(b);
}
if (round)
{
a = Math.Round(a);
b = Math.Round(b);
}
// Now do the comparison
switch (op)
{
case "=":
return a == b;
case "<":
return a < b;
case ">":
return a > b;
case "!=":
return a != b;
case "<=":
return a <= b;
case ">=":
return a >= b;
case "[":
return a.ToString().StartsWith(b.ToString());
case "]":
return a.ToString().EndsWith(b.ToString());
case "?":
return a.ToString().Contains(b.ToString());
case "!?":
return !a.ToString().Contains(b.ToString());
}
break;
case "date":
if (val1.Length == 0 || val2.Length == 0)
return false;
DateTime aa;
DateTime bb;
DateTime defaultPassthrough = DateTime.MinValue.AddSeconds(7);
var culture = Sitecore.Context.Culture;
if (culture.IsNeutralCulture)
culture = Thread.CurrentThread.CurrentCulture;
aa = Sitecore.DateUtil.ParseDateTime(val1, defaultPassthrough, culture);
if (aa == defaultPassthrough)
throw new ExpressionException(string.Format("{0} is not a date", val1));
bb = Sitecore.DateUtil.ParseDateTime(val2, defaultPassthrough, culture);
if (bb == defaultPassthrough)
throw new ExpressionException(string.Format("{0} is not a date", val2));
// Now do the comparison
switch (op)
{
case "=":
return aa == bb;
case "<":
return aa < bb;
case ">":
return aa > bb;
case "!=":
return aa != bb;
case "<=":
return aa <= bb;
case ">=":
return aa >= bb;
}
break;
}
// Something went wrong if we get to here
return false;
}
public static string GetItemAttribute(Item item, string name)
{
var inspector = new ItemInspector(item);
return inspector.GetItemAttribute(name);
}