public override Type EvaluateType()
{
var leftType = LeftExpression.EvaluateType();
var rightType = RightExpression.EvaluateType();
var leftTypeUnboxed = TypeHelper.GetUnderlyingTypeIfNullable(leftType);
var rightTypeUnboxed = TypeHelper.GetUnderlyingTypeIfNullable(rightType);
var anyNullable = TypeHelper.IsSystemNullableType(leftType) || TypeHelper.IsSystemNullableType(rightType);
Type resultedTypeRaw;
switch (Operator.Type)
{
case BinaryOperatorType.Logical:
// For logical comparison, we ensure that all operands' type are logical already
// The return type is always boolean (logical)
if (leftType != typeof(bool) || leftType != typeof(bool?) &&
rightType != typeof(bool) || rightType != typeof(bool?))
{
throw new TranspilerNotSupportedException($"Logical binary operator {Operator} operating must operate on bool types. Actual types: {leftType}, {rightType}");
}
return(anyNullable ? TypeHelper.MakeNullableIfNotAlready(typeof(bool)) : typeof(bool));
case BinaryOperatorType.Value:
// For value type operator, use the value type coercion table
if (!TypeCoersionTables.CoersionTableForValueType.TryGetValue((Operator.Name, leftTypeUnboxed, rightTypeUnboxed), out resultedTypeRaw))
{
throw new TranspilerInternalErrorException($"Unexpected use of binary operator {Operator.Name} operating between types {leftTypeUnboxed} and {rightTypeUnboxed}");
}
if (resultedTypeRaw == default(Type))
{
throw new TranspilerNotSupportedException($"Binary operator {Operator.Name} operating between types {leftTypeUnboxed} and {rightTypeUnboxed}");
}
return(anyNullable ? TypeHelper.MakeNullableIfNotAlready(resultedTypeRaw) : resultedTypeRaw);
case BinaryOperatorType.Comparison:
// For comparison operators, use the equality/inequality type coercion table
if (Operator.Name == BinaryOperator.EQ || Operator.Name == BinaryOperator.NEQ)
{
if (!TypeCoersionTables.CoersionTableEqualityComparison.TryGetValue((leftTypeUnboxed, rightTypeUnboxed), out resultedTypeRaw))
{
throw new TranspilerInternalErrorException($"Unexpected use of binary operator {Operator.Name} operating between types {leftTypeUnboxed} and {rightTypeUnboxed}");
}
}
else
{
if (!TypeCoersionTables.CoersionTableInequalityComparison.TryGetValue((leftTypeUnboxed, rightTypeUnboxed), out resultedTypeRaw))
{
throw new TranspilerInternalErrorException($"Unexpected use of binary operator {Operator.Name} operating between types {leftTypeUnboxed} and {rightTypeUnboxed}");
}
}
if (resultedTypeRaw == default(Type))
{
throw new TranspilerNotSupportedException($"Binary operator {Operator.Name} operating between types {leftTypeUnboxed} and {rightTypeUnboxed}");
}
return(anyNullable ? TypeHelper.MakeNullableIfNotAlready(resultedTypeRaw) : resultedTypeRaw);
case BinaryOperatorType.Invalid:
default:
throw new TranspilerInternalErrorException($"Unexpected operator type: {Operator.Type}");
}
}