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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT LIBRARY COMPONENTS --
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4 -- --
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5 -- A D A . C O N T A I N E R S . I N D E F I N I T E _ H O L D E R S --
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6 -- --
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7 -- B o d y --
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8 -- --
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131
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9 -- Copyright (C) 2012-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 ------------------------------------------------------------------------------
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27
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28 with Ada.Unchecked_Deallocation;
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29
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30 package body Ada.Containers.Indefinite_Holders is
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31
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32 procedure Free is
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33 new Ada.Unchecked_Deallocation (Element_Type, Element_Access);
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34
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35 ---------
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36 -- "=" --
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37 ---------
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38
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39 function "=" (Left, Right : Holder) return Boolean is
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40 begin
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41 if Left.Element = null and Right.Element = null then
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42 return True;
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43 elsif Left.Element /= null and Right.Element /= null then
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44 return Left.Element.all = Right.Element.all;
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45 else
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46 return False;
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47 end if;
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48 end "=";
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49
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50 ------------
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51 -- Adjust --
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52 ------------
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53
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54 overriding procedure Adjust (Container : in out Holder) is
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55 begin
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56 if Container.Element /= null then
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57 Container.Element := new Element_Type'(Container.Element.all);
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58 end if;
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59
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60 Container.Busy := 0;
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61 end Adjust;
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62
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63 overriding procedure Adjust (Control : in out Reference_Control_Type) is
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64 begin
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65 if Control.Container /= null then
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66 declare
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67 B : Natural renames Control.Container.Busy;
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68 begin
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69 B := B + 1;
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70 end;
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71 end if;
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72 end Adjust;
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73
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74 ------------
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75 -- Assign --
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76 ------------
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77
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78 procedure Assign (Target : in out Holder; Source : Holder) is
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79 begin
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80 if Target.Busy /= 0 then
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81 raise Program_Error with "attempt to tamper with elements";
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82 end if;
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83
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84 if Target.Element /= Source.Element then
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85 Free (Target.Element);
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86
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87 if Source.Element /= null then
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88 Target.Element := new Element_Type'(Source.Element.all);
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89 end if;
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90 end if;
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91 end Assign;
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92
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93 -----------
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94 -- Clear --
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95 -----------
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96
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97 procedure Clear (Container : in out Holder) is
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98 begin
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99 if Container.Busy /= 0 then
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100 raise Program_Error with "attempt to tamper with elements";
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101 end if;
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102
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103 Free (Container.Element);
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104 end Clear;
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105
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106 ------------------------
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107 -- Constant_Reference --
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108 ------------------------
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109
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110 function Constant_Reference
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111 (Container : aliased Holder) return Constant_Reference_Type
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112 is
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113 Ref : constant Constant_Reference_Type :=
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114 (Element => Container.Element.all'Access,
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115 Control => (Controlled with Container'Unrestricted_Access));
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116 B : Natural renames Ref.Control.Container.Busy;
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117 begin
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118 B := B + 1;
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119 return Ref;
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120 end Constant_Reference;
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121
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122 ----------
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123 -- Copy --
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124 ----------
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125
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126 function Copy (Source : Holder) return Holder is
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127 begin
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128 if Source.Element = null then
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129 return (Controlled with null, 0);
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130 else
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131 return (Controlled with new Element_Type'(Source.Element.all), 0);
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132 end if;
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133 end Copy;
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134
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135 -------------
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136 -- Element --
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137 -------------
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138
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139 function Element (Container : Holder) return Element_Type is
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140 begin
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141 if Container.Element = null then
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142 raise Constraint_Error with "container is empty";
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143 else
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144 return Container.Element.all;
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145 end if;
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146 end Element;
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147
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148 --------------
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149 -- Finalize --
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150 --------------
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151
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152 overriding procedure Finalize (Container : in out Holder) is
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153 begin
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154 if Container.Busy /= 0 then
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155 raise Program_Error with "attempt to tamper with elements";
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156 end if;
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157
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158 Free (Container.Element);
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159 end Finalize;
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160
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161 overriding procedure Finalize (Control : in out Reference_Control_Type) is
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162 begin
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163 if Control.Container /= null then
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164 declare
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165 B : Natural renames Control.Container.Busy;
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166 begin
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167 B := B - 1;
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168 end;
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169 end if;
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170
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171 Control.Container := null;
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172 end Finalize;
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173
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174 --------------
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175 -- Is_Empty --
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176 --------------
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177
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178 function Is_Empty (Container : Holder) return Boolean is
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179 begin
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180 return Container.Element = null;
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181 end Is_Empty;
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182
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183 ----------
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184 -- Move --
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185 ----------
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186
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187 procedure Move (Target : in out Holder; Source : in out Holder) is
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188 begin
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189 if Target.Busy /= 0 then
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190 raise Program_Error with "attempt to tamper with elements";
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191 end if;
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192
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193 if Source.Busy /= 0 then
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194 raise Program_Error with "attempt to tamper with elements";
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195 end if;
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196
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197 if Target.Element /= Source.Element then
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198 Free (Target.Element);
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199 Target.Element := Source.Element;
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200 Source.Element := null;
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201 end if;
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202 end Move;
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203
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204 -------------------
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205 -- Query_Element --
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206 -------------------
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207
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208 procedure Query_Element
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209 (Container : Holder;
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210 Process : not null access procedure (Element : Element_Type))
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211 is
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212 B : Natural renames Container'Unrestricted_Access.Busy;
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213
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214 begin
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215 if Container.Element = null then
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216 raise Constraint_Error with "container is empty";
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217 end if;
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218
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219 B := B + 1;
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220
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221 begin
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222 Process (Container.Element.all);
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223 exception
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224 when others =>
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225 B := B - 1;
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226 raise;
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227 end;
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228
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229 B := B - 1;
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230 end Query_Element;
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231
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232 ----------
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233 -- Read --
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234 ----------
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235
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236 procedure Read
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237 (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
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238 Container : out Holder)
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239 is
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240 begin
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241 Clear (Container);
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242
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243 if not Boolean'Input (Stream) then
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244 Container.Element := new Element_Type'(Element_Type'Input (Stream));
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245 end if;
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246 end Read;
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247
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248 procedure Read
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249 (Stream : not null access Root_Stream_Type'Class;
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250 Item : out Constant_Reference_Type)
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251 is
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252 begin
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253 raise Program_Error with "attempt to stream reference";
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254 end Read;
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255
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256 procedure Read
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257 (Stream : not null access Root_Stream_Type'Class;
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258 Item : out Reference_Type)
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259 is
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260 begin
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261 raise Program_Error with "attempt to stream reference";
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262 end Read;
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263
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264 ---------------
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265 -- Reference --
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266 ---------------
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267
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268 function Reference
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269 (Container : aliased in out Holder) return Reference_Type
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270 is
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271 Ref : constant Reference_Type :=
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272 (Element => Container.Element.all'Access,
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273 Control => (Controlled with Container'Unrestricted_Access));
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274 begin
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275 Container.Busy := Container.Busy + 1;
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276 return Ref;
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277 end Reference;
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278
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279 ---------------------
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280 -- Replace_Element --
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281 ---------------------
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282
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283 procedure Replace_Element
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284 (Container : in out Holder;
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285 New_Item : Element_Type)
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286 is
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287 begin
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288 if Container.Busy /= 0 then
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289 raise Program_Error with "attempt to tamper with elements";
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290 end if;
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291
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292 declare
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293 X : Element_Access := Container.Element;
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294
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295 -- Element allocator may need an accessibility check in case actual
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296 -- type is class-wide or has access discriminants (RM 4.8(10.1) and
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297 -- AI12-0035).
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298
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299 pragma Unsuppress (Accessibility_Check);
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300
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301 begin
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302 Container.Element := new Element_Type'(New_Item);
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303 Free (X);
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304 end;
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305 end Replace_Element;
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306
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307 ---------------
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308 -- To_Holder --
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309 ---------------
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310
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311 function To_Holder (New_Item : Element_Type) return Holder is
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312
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313 -- The element allocator may need an accessibility check in the case the
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314 -- actual type is class-wide or has access discriminants (RM 4.8(10.1)
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315 -- and AI12-0035).
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316
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317 pragma Unsuppress (Accessibility_Check);
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318
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319 begin
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320 return (Controlled with new Element_Type'(New_Item), 0);
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321 end To_Holder;
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322
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323 --------------------
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324 -- Update_Element --
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325 --------------------
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326
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327 procedure Update_Element
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328 (Container : in out Holder;
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329 Process : not null access procedure (Element : in out Element_Type))
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330 is
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331 B : Natural renames Container.Busy;
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332
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333 begin
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334 if Container.Element = null then
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335 raise Constraint_Error with "container is empty";
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336 end if;
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337
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338 B := B + 1;
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339
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340 begin
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341 Process (Container.Element.all);
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342 exception
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343 when others =>
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344 B := B - 1;
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345 raise;
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346 end;
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347
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348 B := B - 1;
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349 end Update_Element;
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350
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351 -----------
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352 -- Write --
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353 -----------
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354
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355 procedure Write
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356 (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
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357 Container : Holder)
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358 is
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359 begin
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360 Boolean'Output (Stream, Container.Element = null);
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361
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362 if Container.Element /= null then
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363 Element_Type'Output (Stream, Container.Element.all);
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364 end if;
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365 end Write;
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366
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367 procedure Write
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368 (Stream : not null access Root_Stream_Type'Class;
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369 Item : Reference_Type)
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370 is
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371 begin
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372 raise Program_Error with "attempt to stream reference";
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373 end Write;
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374
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375 procedure Write
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376 (Stream : not null access Root_Stream_Type'Class;
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377 Item : Constant_Reference_Type)
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378 is
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379 begin
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380 raise Program_Error with "attempt to stream reference";
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381 end Write;
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382
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383 end Ada.Containers.Indefinite_Holders;
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