protected override Expression DoResolve (ResolveContext ec)
{
unwrap = Unwrap.Create (Expr, false);
if (unwrap == null)
return null;
Expression res = base.ResolveOperator (ec, unwrap);
if (res == null) {
Error_OperatorCannotBeApplied (ec, loc, OperName (Oper), Expr.Type);
return null;
}
if (res != this) {
if (user_operator == null)
return res;
} else {
res = Expr = LiftExpression (ec, Expr);
}
if (res == null)
return null;
eclass = ExprClass.Value;
type = res.Type;
return this;
}
public LiftedConversion (Expression expr, Unwrap unwrap, TypeSpec type)
{
this.expr = expr;
this.unwrap = unwrap;
this.loc = expr.Location;
this.type = type;
}
public override bool Equals(object obj)
{
Unwrap uw = obj as Unwrap;
return(uw != null && expr.Equals(uw.expr));
}
Expression ConvertExpression (ResolveContext ec)
{
// TODO: ImplicitConversionExists should take care of this
if (left.eclass == ExprClass.MethodGroup)
return null;
TypeSpec ltype = left.Type;
//
// If left is a nullable type and an implicit conversion exists from right to underlying type of left,
// the result is underlying type of left
//
if (ltype.IsNullableType) {
unwrap = Unwrap.Create (left, false);
if (unwrap == null)
return null;
//
// Reduce (left ?? null) to left
//
if (right.IsNull)
return ReducedExpression.Create (left, this);
Expression conv;
if (right.Type.IsNullableType) {
conv = right.Type == ltype ? right : Convert.ImplicitNulableConversion (ec, right, ltype);
if (conv != null) {
right = conv;
type = ltype;
return this;
}
} else {
conv = Convert.ImplicitConversion (ec, right, unwrap.Type, loc);
if (conv != null) {
left = unwrap;
ltype = left.Type;
//
// If right is a dynamic expression, the result type is dynamic
//
if (right.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
type = right.Type;
// Need to box underlying value type
left = Convert.ImplicitBoxingConversion (left, ltype, type);
return this;
}
right = conv;
type = ltype;
return this;
}
}
} else if (TypeSpec.IsReferenceType (ltype)) {
if (Convert.ImplicitConversionExists (ec, right, ltype)) {
//
// If right is a dynamic expression, the result type is dynamic
//
if (right.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
type = right.Type;
return this;
}
//
// Reduce ("foo" ?? expr) to expression
//
Constant lc = left as Constant;
if (lc != null && !lc.IsDefaultValue)
return ReducedExpression.Create (lc, this, false);
//
// Reduce (left ?? null) to left OR (null-constant ?? right) to right
//
if (right.IsNull || lc != null) {
//
// Special case null ?? null
//
if (right.IsNull && ltype == right.Type)
return null;
return ReducedExpression.Create (lc != null ? right : left, this, false);
}
right = Convert.ImplicitConversion (ec, right, ltype, loc);
type = ltype;
return this;
}
} else {
return null;
}
TypeSpec rtype = right.Type;
if (!Convert.ImplicitConversionExists (ec, unwrap ?? left, rtype) || right.eclass == ExprClass.MethodGroup)
return null;
//
// Reduce (null ?? right) to right
//
if (left.IsNull)
return ReducedExpression.Create (right, this, false).Resolve (ec);
left = Convert.ImplicitConversion (ec, unwrap ?? left, rtype, loc);
type = rtype;
return this;
}
Expression ConvertExpression(ResolveContext ec)
{
// TODO: ImplicitConversionExists should take care of this
if (left.eclass == ExprClass.MethodGroup)
{
return(null);
}
TypeSpec ltype = left.Type;
//
// If left is a nullable type and an implicit conversion exists from right to underlying type of left,
// the result is underlying type of left
//
if (ltype.IsNullableType)
{
unwrap = Unwrap.Create(left, false);
if (unwrap == null)
{
return(null);
}
//
// Reduce (left ?? null) to left
//
if (right.IsNull)
{
return(ReducedExpression.Create(left, this));
}
Expression conv;
if (right.Type.IsNullableType)
{
conv = right.Type == ltype ? right : Convert.ImplicitNulableConversion(ec, right, ltype);
if (conv != null)
{
right = conv;
type = ltype;
return(this);
}
}
else
{
conv = Convert.ImplicitConversion(ec, right, unwrap.Type, loc);
if (conv != null)
{
left = unwrap;
ltype = left.Type;
//
// If right is a dynamic expression, the result type is dynamic
//
if (right.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
{
type = right.Type;
// Need to box underlying value type
left = Convert.ImplicitBoxingConversion(left, ltype, type);
return(this);
}
right = conv;
type = ltype;
return(this);
}
}
}
else if (TypeSpec.IsReferenceType(ltype))
{
if (Convert.ImplicitConversionExists(ec, right, ltype))
{
//
// If right is a dynamic expression, the result type is dynamic
//
if (right.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
{
type = right.Type;
return(this);
}
//
// Reduce ("foo" ?? expr) to expression
//
Constant lc = left as Constant;
if (lc != null && !lc.IsDefaultValue)
{
return(ReducedExpression.Create(lc, this, false));
}
//
// Reduce (left ?? null) to left OR (null-constant ?? right) to right
//
if (right.IsNull || lc != null)
{
//
// Special case null ?? null
//
if (right.IsNull && ltype == right.Type)
{
return(null);
}
return(ReducedExpression.Create(lc != null ? right : left, this, false));
}
right = Convert.ImplicitConversion(ec, right, ltype, loc);
type = ltype;
return(this);
}
}
else
{
return(null);
}
TypeSpec rtype = right.Type;
if (!Convert.ImplicitConversionExists(ec, unwrap ?? left, rtype) || right.eclass == ExprClass.MethodGroup)
{
return(null);
}
//
// Reduce (null ?? right) to right
//
if (left.IsNull)
{
return(ReducedExpression.Create(right, this, false).Resolve(ec));
}
left = Convert.ImplicitConversion(ec, unwrap ?? left, rtype, loc);
type = rtype;
return(this);
}