public void TestNull()
{
var f = new NullConstant();
var res = Util.NullConstant.Compile(f);
HasValue(res, null);
}
protected override Expression DoResolve(ResolveContext ec)
{
//
// It's null when lifting non-nullable type
//
if (unwrap == null) {
// S -> T? is wrap only
if (type.IsNullableType)
return Wrap.Create (expr, type);
// S -> T can be simplified
return expr;
}
// Wrap target for T?
if (type.IsNullableType) {
if (!expr.Type.IsNullableType) {
expr = Wrap.Create (expr, type);
if (expr == null)
return null;
}
null_value = LiftedNull.Create (type, loc);
} else if (TypeSpec.IsValueType (type)) {
null_value = LiftedNull.Create (type, loc);
} else {
null_value = new NullConstant (type, loc);
}
eclass = ExprClass.Value;
return this;
}
public static void CompileNull(ParserContext parser, ByteBuffer buffer, NullConstant nullConstant, bool outputUsed)
{
if (!outputUsed)
{
throw new ParserException(nullConstant, "This expression doesn't do anything.");
}
buffer.Add(nullConstant.FirstToken, OpCode.LITERAL, parser.GetNullConstant());
}
public void TestNulls()
{
var a = new NullConstant();
var b = new NullConstant();
Assert.True(a.Equals(b));
Assert.True(b.Equals(a));
Assert.True(a.GetHashCode() == b.GetHashCode());
a.Alias = new Identifier("fasdf");
Assert.False(a.Equals(b));
Assert.False(b.Equals(a));
Assert.False(a.GetHashCode() == b.GetHashCode());
b.Alias = new Identifier("fasdf");
Assert.True(a.Equals(b));
Assert.True(b.Equals(a));
Assert.True(a.GetHashCode() == b.GetHashCode());
var c = new BooleanIsNull(new ColumnRef("col1"), false);
var d = (BooleanIsNull)c.Clone();
Assert.True(c.left.Equals(d.left));
}
protected override Expression DoResolve (ResolveContext ec)
{
//
// It's null when lifting non-nullable type
//
if (unwrap == null) {
// S -> T? is wrap only
if (type.IsNullableType)
return Wrap.Create (expr, type);
// S -> T can be simplified
return expr;
}
// Wrap target for T?
if (type.IsNullableType) {
expr = Wrap.Create (expr, type);
if (expr == null)
return null;
null_value = LiftedNull.Create (type, loc);
} else if (TypeManager.IsValueType (type)) {
null_value = LiftedNull.Create (type, loc);
} else {
null_value = new NullConstant (type, loc);
}
eclass = ExprClass.Value;
return this;
}
protected abstract void TranslateNullConstant(List <string> output, NullConstant nullConstant);
protected override void TranslateNullConstant(List <string> output, NullConstant nullConstant)
{
output.Add("null");
}
public void VisitNullConstant(NullConstant nullConstant)
{
_builder.Append("null");
}
