private DataType InferBinaryExpressionType(
BinaryExpressionSyntax binaryExpression)
{
InferExpressionType(binaryExpression.LeftOperand);
var leftType = binaryExpression.LeftOperand.Type;
var @operator = binaryExpression.Operator;
InferExpressionType(binaryExpression.RightOperand);
var rightType = binaryExpression.RightOperand.Type;
// If either is unknown, then we can't know whether there is a a problem.
// Note that the operator could be overloaded
if (leftType == DataType.Unknown || rightType == DataType.Unknown)
{
return(binaryExpression.Type = DataType.Unknown);
}
bool compatible;
switch (@operator)
{
case BinaryOperator.Plus:
case BinaryOperator.Minus:
case BinaryOperator.Asterisk:
case BinaryOperator.Slash:
compatible = NumericOperatorTypesAreCompatible(ref binaryExpression.LeftOperand, ref binaryExpression.RightOperand, null);
binaryExpression.Type = compatible ? leftType : DataType.Unknown;
break;
case BinaryOperator.EqualsEquals:
case BinaryOperator.NotEqual:
case BinaryOperator.LessThan:
case BinaryOperator.LessThanOrEqual:
case BinaryOperator.GreaterThan:
case BinaryOperator.GreaterThanOrEqual:
compatible = (leftType == DataType.Bool && rightType == DataType.Bool) ||
NumericOperatorTypesAreCompatible(ref binaryExpression.LeftOperand, ref binaryExpression.RightOperand, null);
binaryExpression.Type = DataType.Bool;
break;
case BinaryOperator.And:
case BinaryOperator.Or:
compatible = leftType == DataType.Bool && rightType == DataType.Bool;
binaryExpression.Type = DataType.Bool;
break;
default:
throw NonExhaustiveMatchException.ForEnum(@operator);
}
if (!compatible)
{
diagnostics.Add(TypeError.OperatorCannotBeAppliedToOperandsOfType(file,
binaryExpression.Span, @operator,
binaryExpression.LeftOperand.Type,
binaryExpression.RightOperand.Type));
}
return(binaryExpression.Type);
}
