vala/valareferencetransferexpression.vala

   1 /* valareferencetransferexpression.vala
   2  *
   3  * Copyright (C) 2007-2010  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
  23
  24 /**
  25  * Represents a reference transfer expression in the source code, e.g. `#foo`.
  26  */
  27 public class Vala.ReferenceTransferExpression : Expression {
  28         /**
  29          * The variable whose reference is to be transferred.
  30          */
  31         public Expression inner {
  32                 get {
  33                         return _inner;
  34                 }
  35                 set {
  36                         _inner = value;
  37                         _inner.parent_node = this;
  38                 }
  39         }
  40
  41         private Expression _inner;
  42
  43         /**
  44          * Creates a new reference transfer expression.
  45          *
  46          * @param inner variable whose reference is to be transferred
  47          * @return      newly created reference transfer expression
  48          */
  49         public ReferenceTransferExpression (Expression inner, SourceReference? source_reference = null) {
  50                 this.inner = inner;
  51                 this.source_reference = source_reference;
  52         }
  53
  54         public override void accept (CodeVisitor visitor) {
  55                 visitor.visit_reference_transfer_expression (this);
  56
  57                 visitor.visit_expression (this);
  58         }
  59
  60         public override void accept_children (CodeVisitor visitor) {
  61                 inner.accept (visitor);
  62         }
  63
  64         public override void replace_expression (Expression old_node, Expression new_node) {
  65                 if (inner == old_node) {
  66                         inner = new_node;
  67                 }
  68         }
  69
  70         public override bool is_pure () {
  71                 return false;
  72         }
  73
  74         public override bool check (CodeContext context) {
  75                 if (checked) {
  76                         return !error;
  77                 }
  78
  79                 checked = true;
  80
  81                 inner.lvalue = true;
  82
  83                 inner.check (context);
  84
  85                 if (inner.error) {
  86                         /* if there was an error in the inner expression, skip type check */
  87                         error = true;
  88                         return false;
  89                 }
  90
  91                 if (!(inner is MemberAccess || inner is ElementAccess)) {
  92                         error = true;
  93                         Report.error (source_reference, "Reference transfer not supported for this expression");
  94                         return false;
  95                 }
  96
  97                 if (!inner.value_type.is_disposable ()
  98                     && !(inner.value_type is PointerType)) {
  99                         error = true;
 100                         Report.error (source_reference, "No reference to be transferred");
 101                         return false;
 102                 }
 103
 104                 value_type = inner.value_type.copy ();
 105                 value_type.value_owned = true;
 106
 107                 return !error;
 108         }
 109
 110         public override void emit (CodeGenerator codegen) {
 111                 inner.emit (codegen);
 112
 113                 codegen.visit_reference_transfer_expression (this);
 114
 115                 codegen.visit_expression (this);
 116         }
 117
 118         public override void get_defined_variables (Collection<LocalVariable> collection) {
 119                 inner.get_defined_variables (collection);
 120         }
 121
 122         public override void get_used_variables (Collection<LocalVariable> collection) {
 123                 inner.get_used_variables (collection);
 124         }
 125 }