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 is_accessible (Symbol sym) {
  75                 return inner.is_accessible (sym);
  76         }
  77
  78         public override bool check (CodeContext context) {
  79                 if (checked) {
  80                         return !error;
  81                 }
  82
  83                 checked = true;
  84
  85                 inner.lvalue = true;
  86
  87                 inner.check (context);
  88
  89                 if (inner.error) {
  90                         /* if there was an error in the inner expression, skip type check */
  91                         error = true;
  92                         return false;
  93                 }
  94
  95                 if (!(inner is MemberAccess || inner is ElementAccess)) {
  96                         error = true;
  97                         Report.error (source_reference, "Reference transfer not supported for this expression");
  98                         return false;
  99                 }
 100
 101                 var is_owned_delegate = inner.value_type is DelegateType && inner.value_type.value_owned;
 102                 if (!inner.value_type.is_disposable ()
 103                     && !(inner.value_type is PointerType)
 104                         && !is_owned_delegate) {
 105                         error = true;
 106                         Report.error (source_reference, "No reference to be transferred");
 107                         return false;
 108                 }
 109
 110                 value_type = inner.value_type.copy ();
 111                 value_type.value_owned = true;
 112
 113                 return !error;
 114         }
 115
 116         public override void emit (CodeGenerator codegen) {
 117                 inner.emit (codegen);
 118
 119                 codegen.visit_reference_transfer_expression (this);
 120
 121                 codegen.visit_expression (this);
 122         }
 123
 124         public override void get_defined_variables (Collection<Variable> collection) {
 125                 inner.get_defined_variables (collection);
 126                 var local = inner.symbol_reference as LocalVariable;
 127                 var param = inner.symbol_reference as Parameter;
 128                 if (local != null) {
 129                         collection.add (local);
 130                 } else if (param != null && param.direction == ParameterDirection.OUT) {
 131                         collection.add (param);
 132                 }
 133         }
 134
 135         public override void get_used_variables (Collection<Variable> collection) {
 136                 inner.get_used_variables (collection);
 137                 var local = inner.symbol_reference as LocalVariable;
 138                 var param = inner.symbol_reference as Parameter;
 139                 if (local != null) {
 140                         collection.add (local);
 141                 } else if (param != null && param.direction == ParameterDirection.OUT) {
 142                         collection.add (param);
 143                 }
 144         }
 145 }