/// <summary>
/// Evaluates to the final value, found based on the stored (and evaluated) property identifiers,
/// and optionally the given parameters.
/// Returns null inc ase something went wrong.
/// </summary>
public override L20nObject Eval(LocaleContext ctx, params L20nObject[] argv)
{
L20nObject maybe;
int i = 0;
// The root entity is either given as a parameter
// or we need to get it using the first identifier.
// See this.GetEntity for more information.
if (argv == null || argv.Length == 0 || argv [0] as Dummy != null)
{
maybe = GetEntity(ctx, m_Identifiers [i]);
i += 1;
} else
{
maybe = argv [0];
}
// return null in case we have no root entity at all
if (maybe == null)
{
Logger.Warning("<PropertyExpression>: couldn't evaluate first expression");
return maybe;
}
L20nObject obj = maybe;
// in case this property is pointing to a root entity,
// directly requested by the L20n-user, we need to
// evaluate it using the current identifier, such that
// we can return null in case the Entity is private
// and should thus not be requested.
if (argv.Length == 1 && i < m_Identifiers.Length && (argv [0] as Dummy) != null)
{
obj = obj.Eval(ctx, argv [0], m_Identifiers [i]);
++i;
}
// go through each identifier and replace the current Entity,
// such that we can go deeper until we went through the
// entire identifier list.
for (; i < m_Identifiers.Length; ++i)
{
if (obj == null)
{
Logger.WarningFormat(
"<PropertyExpression>: couldn't evaluate expression #{0}", i);
return obj;
}
// check if we are dealing with a string
// in which case we want to make it into an identifierExpression
var stringObject = obj as StringOutput;
if (stringObject != null)
{
// we do want to fall back to it being just a regular string,
// in case that was the actual intention of the user
L20nObject alt = new IdentifierExpression(stringObject.Value);
alt = alt.Eval(ctx, m_Identifiers [i]);
if (alt != null)
{
obj = alt;
continue;
}
}
obj = obj.Eval(ctx, m_Identifiers [i]);
}
if (obj == null)
{
Logger.Warning(
"<PropertyExpression>: couldn't evaluate the final expression");
return obj;
}
// if all is fine, we can now return the evaluation
// of the last found value.
return obj.Eval(ctx);
}