public override Lazy <object> VisitIndexerExpression(QuestScriptParser.IndexerExpressionContext context)
{
//this does necessary type checks.
var valueType = _scriptEnvironmentBuilder.TypeInferenceVisitor.Visit(context);
if (valueType == ObjectType.Unknown) //failed at one or more type checks
{
return(new Lazy <object>(() => null));
}
var instanceType = _scriptEnvironmentBuilder.TypeInferenceVisitor.Visit(context.instance);
if (instanceType == ObjectType.List)
{
return(new Lazy <object>(() =>
{
//we can assume those types are there because we did type checks with TypeInferenceVisitor
var listArray = (ArrayList)context.instance.Accept(this).Value.GetValueOrLazyValue();
return listArray[int.Parse(context.parameter.Accept(this).Value.GetValueOrLazyValue().ToString())];
}));
}
if (instanceType == ObjectType.Dictionary)
{
throw new NotImplementedException("Support for dictionaries is currently not implemented");
}
_scriptEnvironmentBuilder.Errors.Add(new UnexpectedTypeException(context, ObjectType.List, instanceType,
context.instance,
$"Indexer expression must be applied to either list or a dictionary, and this was '{instanceType}'."));
return(base.VisitIndexerExpression(context));
}
public override ObjectType VisitIndexerExpression(QuestScriptParser.IndexerExpressionContext context)
{
var variableType = context.instance.Accept(this);
if (variableType == ObjectType.List)
{
//first verify that the indexer parameter is integer, otherwise
//in the context of lists the expression makes no sense
var parameterType = context.parameter.Accept(this);
if (!TypeUtil.IsNumeric(parameterType))
{
_scriptEnvironmentBuilder.Errors.Add(
new UnexpectedTypeException(
context, ObjectType.Integer,
parameterType,
context.parameter,
"When using list accessor, the index should be of integer type. For example 'x = list[23]' is a valid statement."));
return(ObjectType.Unknown);
}
//at this point the expression we are accessing through indexer SHOULD be evaluable,
//so we are simply resolving it's value sooner
var value = _scriptEnvironmentBuilder.ValueResolverVisitor.Visit(context.instance).Value
.GetValueOrLazyValue();
var valueAsArray = value as ArrayList;
if (valueAsArray == null) //precaution, shouldn't happen
{
if (!TypeUtil.TryConvertType(value.GetType(), out var resultingType))
{
resultingType = ObjectType.Unknown;
}
_scriptEnvironmentBuilder.Errors.Add(
new UnexpectedTypeException(
context, ObjectType.List,
resultingType,
context.parameter,
$"Expected {context.instance.GetText()} to be a 'ObjectType.List', but it is '{resultingType}'. Thus, cannot infer the resulting type of the indexer expression"));
return(ObjectType.Unknown);
}
if (!TypeUtil.TryConvertType(valueAsArray[0].GetType(), out var itemType))
{
itemType = ObjectType.Unknown;
}
return(itemType);
}
//TODO:Add here support for dictionaries (object attributes and function parameter may be of dictionary type)
return(ObjectType.Unknown);
}
