vala/valadelegatetype.vala

   1 /* valadelegatetype.vala
   2  *
   3  * Copyright (C) 2007-2012  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 using GLib;
  24
  25 /**
  26  * The type of an instance of a delegate.
  27  */
  28 public class Vala.DelegateType : CallableType {
  29         public weak Delegate delegate_symbol { get; set; }
  30
  31         public bool is_called_once { get; set; }
  32
  33         public DelegateType (Delegate delegate_symbol) {
  34                 this.delegate_symbol = delegate_symbol;
  35                 this.is_called_once = (delegate_symbol.get_attribute_string ("CCode", "scope") == "async");
  36         }
  37
  38         public override bool is_invokable () {
  39                 return true;
  40         }
  41
  42         public override DataType? get_return_type () {
  43                 return delegate_symbol.return_type;
  44         }
  45
  46         public override List<Parameter>? get_parameters () {
  47                 return delegate_symbol.get_parameters ();
  48         }
  49
  50         public override string to_qualified_string (Scope? scope) {
  51                 // logic temporarily duplicated from DataType class
  52
  53                 Symbol global_symbol = delegate_symbol;
  54                 while (global_symbol.parent_symbol != null && global_symbol.parent_symbol.name != null) {
  55                         global_symbol = global_symbol.parent_symbol;
  56                 }
  57
  58                 Symbol sym = null;
  59                 Scope parent_scope = scope;
  60                 while (sym == null && parent_scope != null) {
  61                         sym = parent_scope.lookup (global_symbol.name);
  62                         parent_scope = parent_scope.parent_scope;
  63                 }
  64
  65                 string s;
  66
  67                 if (sym != null && global_symbol != sym) {
  68                         s = "global::" + delegate_symbol.get_full_name ();;
  69                 } else {
  70                         s = delegate_symbol.get_full_name ();
  71                 }
  72
  73                 var type_args = get_type_arguments ();
  74                 if (type_args.size > 0) {
  75                         s += "<";
  76                         bool first = true;
  77                         foreach (DataType type_arg in type_args) {
  78                                 if (!first) {
  79                                         s += ",";
  80                                 } else {
  81                                         first = false;
  82                                 }
  83                                 if (!type_arg.value_owned) {
  84                                         s += "weak ";
  85                                 }
  86                                 s += type_arg.to_qualified_string (scope);
  87                         }
  88                         s += ">";
  89                 }
  90                 if (nullable) {
  91                         s += "?";
  92                 }
  93                 return s;
  94         }
  95
  96         public override DataType copy () {
  97                 var result = new DelegateType (delegate_symbol);
  98                 result.source_reference = source_reference;
  99                 result.value_owned = value_owned;
 100                 result.nullable = nullable;
 101
 102                 foreach (DataType arg in get_type_arguments ()) {
 103                         result.add_type_argument (arg.copy ());
 104                 }
 105
 106                 result.is_called_once = is_called_once;
 107
 108                 return result;
 109         }
 110
 111         public override bool is_accessible (Symbol sym) {
 112                 return delegate_symbol.is_accessible (sym);
 113         }
 114
 115         public override bool check (CodeContext context) {
 116                 if (is_called_once && !value_owned) {
 117                         Report.warning (source_reference, "delegates with scope=\"async\" must be owned");
 118                 }
 119
 120                 if (!delegate_symbol.check (context)) {
 121                         return false;
 122                 }
 123
 124                 var n_type_params = delegate_symbol.get_type_parameters ().size;
 125                 var n_type_args = get_type_arguments ().size;
 126                 if (n_type_args > 0 && n_type_args < n_type_params) {
 127                         Report.error (source_reference, "too few type arguments");
 128                         return false;
 129                 } else if (n_type_args > 0 && n_type_args > n_type_params) {
 130                         Report.error (source_reference, "too many type arguments");
 131                         return false;
 132                 }
 133
 134                 foreach (DataType type in get_type_arguments ()) {
 135                         if (!type.check (context)) {
 136                                 return false;
 137                         }
 138                 }
 139
 140                 return true;
 141         }
 142
 143         public override bool compatible (DataType target_type) {
 144                 var dt_target = target_type as DelegateType;
 145                 if (dt_target == null) {
 146                         return false;
 147                 }
 148
 149                 // trivial case
 150                 if (delegate_symbol == dt_target.delegate_symbol) {
 151                         return true;
 152                 }
 153
 154                 // target-delegate is allowed to ensure stricter return type (stronger postcondition)
 155                 if (!get_return_type ().stricter (dt_target.get_return_type ().get_actual_type (dt_target, null, this))) {
 156                         return false;
 157                 }
 158
 159                 var parameters = get_parameters ();
 160                 Iterator<Parameter> params_it = parameters.iterator ();
 161
 162                 if (dt_target.delegate_symbol.parent_symbol is Signal && dt_target.delegate_symbol.sender_type != null && parameters.size == dt_target.get_parameters ().size + 1) {
 163                         // target-delegate has sender parameter
 164                         params_it.next ();
 165
 166                         // target-delegate is allowed to accept arguments of looser types (weaker precondition)
 167                         var p = params_it.get ();
 168                         if (!dt_target.delegate_symbol.sender_type.stricter (p.variable_type)) {
 169                                 return false;
 170                         }
 171                 }
 172
 173                 foreach (Parameter param in dt_target.get_parameters ()) {
 174                         /* target-delegate is allowed to accept less arguments */
 175                         if (!params_it.next ()) {
 176                                 break;
 177                         }
 178
 179                         // target-delegate is allowed to accept arguments of looser types (weaker precondition)
 180                         var p = params_it.get ();
 181                         if (!param.variable_type.get_actual_type (this, null, this).stricter (p.variable_type)) {
 182                                 return false;
 183                         }
 184                 }
 185
 186                 /* target-delegate may not expect more arguments */
 187                 if (params_it.next ()) {
 188                         return false;
 189                 }
 190
 191                 // target-delegate may throw less but not more errors than the delegate
 192                 foreach (DataType error_type in get_error_types ()) {
 193                         bool match = false;
 194                         foreach (DataType delegate_error_type in dt_target.get_error_types ()) {
 195                                 if (error_type.compatible (delegate_error_type)) {
 196                                         match = true;
 197                                         break;
 198                                 }
 199                         }
 200
 201                         if (!match) {
 202                                 return false;
 203                         }
 204                 }
 205
 206                 return true;
 207         }
 208
 209         public override bool is_disposable () {
 210                 return delegate_symbol.has_target && value_owned && !is_called_once;
 211         }
 212 }