1/* valanullliteral.vala 2 * 3 * Copyright (C) 2006-2010 Jürg Billeter 4 * 5 * This library is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU Lesser General Public 7 * License as published by the Free Software Foundation; either 8 * version 2.1 of the License, or (at your option) any later version. 9 10 * This library is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 * Lesser General Public License for more details. 14 15 * You should have received a copy of the GNU Lesser General Public 16 * License along with this library; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 18 * 19 * Author: 20 * Jürg Billeter <j@bitron.ch> 21 */ 22 23using GLib; 24 25/** 26 * Represents a literal `null` in the source code. 27 */ 28public class Vala.NullLiteral : Literal { 29 /** 30 * Creates a new null literal. 31 * 32 * @param source reference to source code 33 * @return newly created null literal 34 */ 35 public NullLiteral (SourceReference? source = null) { 36 source_reference = source; 37 } 38 39 public override void accept (CodeVisitor visitor) { 40 visitor.visit_null_literal (this); 41 42 visitor.visit_expression (this); 43 } 44 45 public override string to_string () { 46 return "null"; 47 } 48 49 public override bool is_pure () { 50 return true; 51 } 52 53 public override bool check (CodeContext context) { 54 if (checked) { 55 return !error; 56 } 57 58 checked = true; 59 60 value_type = new NullType (source_reference); 61 62 return !error; 63 } 64 65 public override void emit (CodeGenerator codegen) { 66 codegen.visit_null_literal (this); 67 68 codegen.visit_expression (this); 69 } 70} 71