public override Type EvaluateType()
{
// CASE WHEN's type depends on the most generous type from its branches
// E.g. CASE WHEN <num> ELSE <string> END gives a string type
var hasElseExpression = (ElseExpression != null);
var distinctTypes = hasElseExpression ?
CaseAlternatives.Select(n => n.EvaluateType())
.Union(new List <Type> {
ElseExpression.EvaluateType()
})
.Distinct() :
CaseAlternatives.Select(n => n.EvaluateType())
.Distinct();
var anyNullable = distinctTypes.Any(t => TypeHelper.IsSystemNullableType(t))
// when Else statement is not provided resulting type becomes automatically nullable
|| !hasElseExpression;
var distinctUnboxedTypes = distinctTypes
.Select(t => TypeHelper.GetUnderlyingTypeIfNullable(t)).Distinct();
Type resultUnboxedType;
if (distinctUnboxedTypes.Count() > 1)
{
resultUnboxedType = distinctUnboxedTypes.Aggregate((resType, nextType) =>
{
Type resultedTypeRaw;
if (!TypeCoersionTables.CoersionTableForValueType.TryGetValue((BinaryOperator.Plus, resType, nextType), out resultedTypeRaw))
{
throw new TranspilerInternalErrorException($"Unexpected use of CASE WHEN operating between types {resType} and {nextType}");
}
if (resultedTypeRaw == default(Type))
{
throw new TranspilerNotSupportedException($"Case WHEN operating between types {resType} and {nextType}");
}
return(resultedTypeRaw);
});
}
else
{
resultUnboxedType = distinctUnboxedTypes.First();
}
return(anyNullable ? TypeHelper.MakeNullableIfNotAlready(resultUnboxedType) : resultUnboxedType);
}
public override string ToString()
{
return($"CaseExpr: Case {CaseAlternatives.ToString()} Else->{ElseExpression?.ToString() ?? "(None)"}");
}