/// <summary>
/// Gets the row number in the C# 4.0 spec operator precedence table.
/// </summary>
static int GetPrecedence(Expression expr)
{
// Note: the operator precedence table on MSDN is incorrect
if (expr is QueryExpression)
{
// Not part of the table in the C# spec, but we need to ensure that queries within
// primary expressions get parenthesized.
return(QueryOrLambda);
}
UnaryOperatorExpression uoe = expr as UnaryOperatorExpression;
if (uoe != null)
{
if (uoe.Operator == UnaryOperatorType.PostDecrement || uoe.Operator == UnaryOperatorType.PostIncrement)
{
return(Primary);
}
else
{
return(Unary);
}
}
if (expr is CastExpression)
{
return(Unary);
}
BinaryOperatorExpression boe = expr as BinaryOperatorExpression;
if (boe != null)
{
switch (boe.Operator)
{
case BinaryOperatorType.Multiply:
case BinaryOperatorType.Divide:
case BinaryOperatorType.Modulus:
return(13); // multiplicative
case BinaryOperatorType.Add:
case BinaryOperatorType.Subtract:
return(12); // additive
case BinaryOperatorType.ShiftLeft:
case BinaryOperatorType.ShiftRight:
return(11);
case BinaryOperatorType.GreaterThan:
case BinaryOperatorType.GreaterThanOrEqual:
case BinaryOperatorType.LessThan:
case BinaryOperatorType.LessThanOrEqual:
return(RelationalAndTypeTesting);
case BinaryOperatorType.Equality:
case BinaryOperatorType.InEquality:
return(Equality);
case BinaryOperatorType.BitwiseAnd:
return(8);
case BinaryOperatorType.ExclusiveOr:
return(7);
case BinaryOperatorType.BitwiseOr:
return(6);
case BinaryOperatorType.ConditionalAnd:
return(5);
case BinaryOperatorType.ConditionalOr:
return(4);
case BinaryOperatorType.NullCoalescing:
return(3);
default:
throw new NotSupportedException("Invalid value for BinaryOperatorType");
}
}
if (expr is IsExpression || expr is AsExpression)
{
return(RelationalAndTypeTesting);
}
if (expr is ConditionalExpression)
{
return(Conditional);
}
if (expr is AssignmentExpression || expr is LambdaExpression)
{
return(Assignment);
}
// anything else: primary expression
return(Primary);
}
void IAstVisitor.VisitUnaryOperatorExpression(UnaryOperatorExpression unaryOperatorExpression)
{
Visit(EnterUnaryOperatorExpression, LeaveUnaryOperatorExpression, unaryOperatorExpression);
}
public override void VisitCastExpression(CastExpression castExpression)
{
ParenthesizeIfRequired(castExpression.Expression, InsertParenthesesForReadability ? Primary : Unary);
// There's a nasty issue in the C# grammar: cast expressions including certain operators are ambiguous in some cases
// "(int)-1" is fine, but "(A)-b" is not a cast.
UnaryOperatorExpression uoe = castExpression.Expression as UnaryOperatorExpression;
if (uoe != null && !(uoe.Operator == UnaryOperatorType.BitNot || uoe.Operator == UnaryOperatorType.Not))
{
if (TypeCanBeMisinterpretedAsExpression(castExpression.Type))
{
Parenthesize(castExpression.Expression);
}
}
// The above issue can also happen with PrimitiveExpressions representing negative values:
PrimitiveExpression pe = castExpression.Expression as PrimitiveExpression;
if (pe != null && pe.Value != null && TypeCanBeMisinterpretedAsExpression(castExpression.Type))
{
TypeCode typeCode = Type.GetTypeCode(pe.Value.GetType());
switch (typeCode)
{
case TypeCode.SByte:
if ((sbyte)pe.Value < 0)
{
Parenthesize(castExpression.Expression);
}
break;
case TypeCode.Int16:
if ((short)pe.Value < 0)
{
Parenthesize(castExpression.Expression);
}
break;
case TypeCode.Int32:
if ((int)pe.Value < 0)
{
Parenthesize(castExpression.Expression);
}
break;
case TypeCode.Int64:
if ((long)pe.Value < 0)
{
Parenthesize(castExpression.Expression);
}
break;
case TypeCode.Single:
if ((float)pe.Value < 0)
{
Parenthesize(castExpression.Expression);
}
break;
case TypeCode.Double:
if ((double)pe.Value < 0)
{
Parenthesize(castExpression.Expression);
}
break;
case TypeCode.Decimal:
if ((decimal)pe.Value < 0)
{
Parenthesize(castExpression.Expression);
}
break;
}
}
base.VisitCastExpression(castExpression);
}