protected internal override IValueRef GetValueRef(ExpressionState state)
{
var context = state.GetActiveContextObject();
var target = context.Value;
var targetDescriptor = context.TypeDescriptor;
ITypedValue indexValue;
object index;
// This first part of the if clause prevents a 'double dereference' of the property (SPR-5847)
if (target is System.Collections.IDictionary && (_children[0] is PropertyOrFieldReference reference1))
{
var reference = reference1;
index = reference.Name;
indexValue = new TypedValue(index);
}
else
{
// In case the map key is unqualified, we want it evaluated against the root object
// so temporarily push that on whilst evaluating the key
try
{
state.PushActiveContextObject(state.RootContextObject);
indexValue = _children[0].GetValueInternal(state);
index = indexValue.Value;
if (index == null)
{
throw new InvalidOperationException("No index");
}
}
finally
{
state.PopActiveContextObject();
}
}
// Raise a proper exception in case of a null target
if (target == null)
{
throw new SpelEvaluationException(StartPosition, SpelMessage.CANNOT_INDEX_INTO_NULL_VALUE);
}
// At this point, we need a TypeDescriptor for a non-null target object
if (targetDescriptor == null)
{
throw new InvalidOperationException("No type descriptor");
}
// Indexing into a Map
if (target is System.Collections.IDictionary)
{
var key = index;
var mapkeyType = ReflectionHelper.GetMapKeyTypeDescriptor(targetDescriptor);
if (mapkeyType != null)
{
key = state.ConvertValue(key, mapkeyType);
}
_indexedType = IndexedType.MAP;
return(new MapIndexingValueRef(this, state.TypeConverter, (IDictionary)target, key, targetDescriptor));
}
// If the object is something that looks indexable by an integer,
// attempt to treat the index value as a number
if (target is Array || target is IList || target is string)
{
var idx = (int)state.ConvertValue(index, typeof(int));
if (target is Array)
{
_indexedType = IndexedType.ARRAY;
return(new ArrayIndexingValueRef(this, state.TypeConverter, target, idx, targetDescriptor));
}
else if (target is IList list)
{
_indexedType = IndexedType.LIST;
return(new CollectionIndexingValueRef(this, list, idx, targetDescriptor, state.TypeConverter, state.Configuration.AutoGrowCollections, state.Configuration.MaximumAutoGrowSize));
}
else
{
_indexedType = IndexedType.STRING;
return(new StringIndexingLValue(this, (string)target, idx, targetDescriptor));
}
}
// Try and treat the index value as a property of the context object
// Could call the conversion service to convert the value to a String
var valueType = indexValue.TypeDescriptor;
if (valueType != null && typeof(string) == valueType)
{
_indexedType = IndexedType.OBJECT;
return(new PropertyIndexingValueRef(this, target, (string)index, state.EvaluationContext, targetDescriptor));
}
throw new SpelEvaluationException(StartPosition, SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, targetDescriptor);
}