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/* valanulltype.vala
*
* Copyright (C) 2007-2010 Jürg Billeter
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Author:
* Jürg Billeter <j@bitron.ch>
*/
using GLib;
/**
* The type of the null literal.
*/
public class Vala.NullType : ReferenceType {
public NullType (SourceReference? source_reference = null) {
base (null, source_reference);
this.nullable = true;
}
public override bool compatible (DataType target_type) {
if (CodeContext.get ().experimental_non_null) {
return target_type.nullable;
}
if (!(target_type is PointerType) && (target_type is NullType || (target_type.type_symbol == null && !(target_type is GenericType)))) {
return true;
}
/* null can be cast to any reference or array type or pointer type */
if (target_type is GenericType ||
target_type is PointerType ||
target_type.nullable ||
target_type.type_symbol.get_attribute ("PointerType") != null) {
return true;
}
if (target_type.type_symbol.is_reference_type () ||
target_type is ArrayType ||
target_type is DelegateType) {
return true;
}
/* null is not compatible with any other type (i.e. value types) */
return false;
}
public override DataType copy () {
return new NullType (source_reference);
}
public override bool is_disposable () {
return false;
}
public override string to_qualified_string (Scope? scope = null) {
return "null";
}
}
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