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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 . M U L T I W A Y _ T R E E S --
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6 -- --
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7 -- S p e c --
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8 -- --
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131
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9 -- Copyright (C) 2004-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- This specification is derived from the Ada Reference Manual for use with --
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12 -- GNAT. The copyright notice above, and the license provisions that follow --
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13 -- apply solely to the contents of the part following the private keyword. --
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14 -- --
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15 -- GNAT is free software; you can redistribute it and/or modify it under --
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16 -- terms of the GNU General Public License as published by the Free Soft- --
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17 -- ware Foundation; either version 3, or (at your option) any later ver- --
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18 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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19 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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20 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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21 -- --
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22 -- As a special exception under Section 7 of GPL version 3, you are granted --
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23 -- additional permissions described in the GCC Runtime Library Exception, --
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24 -- version 3.1, as published by the Free Software Foundation. --
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25 -- --
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26 -- You should have received a copy of the GNU General Public License and --
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27 -- a copy of the GCC Runtime Library Exception along with this program; --
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28 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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29 -- <http://www.gnu.org/licenses/>. --
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30 -- --
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31 -- This unit was originally developed by Matthew J Heaney. --
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32 ------------------------------------------------------------------------------
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33
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34 with Ada.Iterator_Interfaces;
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35
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36 with Ada.Containers.Helpers;
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37 private with Ada.Finalization;
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38 private with Ada.Streams;
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39
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40 generic
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41 type Element_Type is private;
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42
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43 with function "=" (Left, Right : Element_Type) return Boolean is <>;
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44
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45 package Ada.Containers.Multiway_Trees is
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46 pragma Annotate (CodePeer, Skip_Analysis);
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47 pragma Preelaborate;
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48 pragma Remote_Types;
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49
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50 type Tree is tagged private
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51 with Constant_Indexing => Constant_Reference,
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52 Variable_Indexing => Reference,
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53 Default_Iterator => Iterate,
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54 Iterator_Element => Element_Type;
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55 pragma Preelaborable_Initialization (Tree);
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56
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57 type Cursor is private;
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58 pragma Preelaborable_Initialization (Cursor);
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59
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60 Empty_Tree : constant Tree;
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61
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62 No_Element : constant Cursor;
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63 function Has_Element (Position : Cursor) return Boolean;
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64
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65 package Tree_Iterator_Interfaces is new
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66 Ada.Iterator_Interfaces (Cursor, Has_Element);
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67
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68 function Equal_Subtree
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69 (Left_Position : Cursor;
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70 Right_Position : Cursor) return Boolean;
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71
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72 function "=" (Left, Right : Tree) return Boolean;
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73
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74 function Is_Empty (Container : Tree) return Boolean;
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75
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76 function Node_Count (Container : Tree) return Count_Type;
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77
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78 function Subtree_Node_Count (Position : Cursor) return Count_Type;
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79
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80 function Depth (Position : Cursor) return Count_Type;
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81
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82 function Is_Root (Position : Cursor) return Boolean;
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83
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84 function Is_Leaf (Position : Cursor) return Boolean;
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85
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86 function Root (Container : Tree) return Cursor;
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87
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88 procedure Clear (Container : in out Tree);
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89
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90 function Element (Position : Cursor) return Element_Type;
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91
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92 procedure Replace_Element
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93 (Container : in out Tree;
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94 Position : Cursor;
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95 New_Item : Element_Type);
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96
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97 procedure Query_Element
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98 (Position : Cursor;
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99 Process : not null access procedure (Element : Element_Type));
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100
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101 procedure Update_Element
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102 (Container : in out Tree;
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103 Position : Cursor;
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104 Process : not null access procedure (Element : in out Element_Type));
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105
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106 type Constant_Reference_Type
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107 (Element : not null access constant Element_Type) is private
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108 with Implicit_Dereference => Element;
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109
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110 type Reference_Type
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111 (Element : not null access Element_Type) is private
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112 with Implicit_Dereference => Element;
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113
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114 function Constant_Reference
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115 (Container : aliased Tree;
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116 Position : Cursor) return Constant_Reference_Type;
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117 pragma Inline (Constant_Reference);
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118
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119 function Reference
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120 (Container : aliased in out Tree;
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121 Position : Cursor) return Reference_Type;
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122 pragma Inline (Reference);
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123
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124 procedure Assign (Target : in out Tree; Source : Tree);
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125
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126 function Copy (Source : Tree) return Tree;
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127
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128 procedure Move (Target : in out Tree; Source : in out Tree);
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129
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130 procedure Delete_Leaf
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131 (Container : in out Tree;
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132 Position : in out Cursor);
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133
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134 procedure Delete_Subtree
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135 (Container : in out Tree;
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136 Position : in out Cursor);
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137
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138 procedure Swap
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139 (Container : in out Tree;
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140 I, J : Cursor);
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141
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142 function Find
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143 (Container : Tree;
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144 Item : Element_Type) return Cursor;
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145
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146 -- This version of the AI:
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147 -- 10-06-02 AI05-0136-1/07
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148 -- declares Find_In_Subtree this way:
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149 --
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150 -- function Find_In_Subtree
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151 -- (Container : Tree;
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152 -- Item : Element_Type;
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153 -- Position : Cursor) return Cursor;
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154 --
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155 -- It seems that the Container parameter is there by mistake, but we need
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156 -- an official ruling from the ARG. ???
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157
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158 function Find_In_Subtree
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159 (Position : Cursor;
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160 Item : Element_Type) return Cursor;
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161
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162 -- This version of the AI:
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163 -- 10-06-02 AI05-0136-1/07
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164 -- declares Ancestor_Find this way:
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165 --
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166 -- function Ancestor_Find
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167 -- (Container : Tree;
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168 -- Item : Element_Type;
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169 -- Position : Cursor) return Cursor;
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170 --
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171 -- It seems that the Container parameter is there by mistake, but we need
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172 -- an official ruling from the ARG. ???
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173
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174 function Ancestor_Find
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175 (Position : Cursor;
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176 Item : Element_Type) return Cursor;
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177
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178 function Contains
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179 (Container : Tree;
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180 Item : Element_Type) return Boolean;
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181
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182 procedure Iterate
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183 (Container : Tree;
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184 Process : not null access procedure (Position : Cursor));
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185
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186 procedure Iterate_Subtree
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187 (Position : Cursor;
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188 Process : not null access procedure (Position : Cursor));
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189
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190 function Iterate (Container : Tree)
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191 return Tree_Iterator_Interfaces.Forward_Iterator'Class;
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192
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193 function Iterate_Subtree (Position : Cursor)
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194 return Tree_Iterator_Interfaces.Forward_Iterator'Class;
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195
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196 function Iterate_Children
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197 (Container : Tree;
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198 Parent : Cursor)
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199 return Tree_Iterator_Interfaces.Reversible_Iterator'Class;
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200
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201 function Child_Count (Parent : Cursor) return Count_Type;
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202
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203 function Child_Depth (Parent, Child : Cursor) return Count_Type;
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204
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205 procedure Insert_Child
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206 (Container : in out Tree;
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207 Parent : Cursor;
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208 Before : Cursor;
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209 New_Item : Element_Type;
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210 Count : Count_Type := 1);
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211
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212 procedure Insert_Child
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213 (Container : in out Tree;
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214 Parent : Cursor;
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215 Before : Cursor;
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216 New_Item : Element_Type;
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217 Position : out Cursor;
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218 Count : Count_Type := 1);
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219
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220 procedure Insert_Child
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221 (Container : in out Tree;
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222 Parent : Cursor;
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223 Before : Cursor;
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224 Position : out Cursor;
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225 Count : Count_Type := 1);
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226
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227 procedure Prepend_Child
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228 (Container : in out Tree;
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229 Parent : Cursor;
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230 New_Item : Element_Type;
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231 Count : Count_Type := 1);
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232
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233 procedure Append_Child
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234 (Container : in out Tree;
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235 Parent : Cursor;
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236 New_Item : Element_Type;
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237 Count : Count_Type := 1);
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238
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239 procedure Delete_Children
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240 (Container : in out Tree;
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241 Parent : Cursor);
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242
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243 procedure Copy_Subtree
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244 (Target : in out Tree;
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245 Parent : Cursor;
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246 Before : Cursor;
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247 Source : Cursor);
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248
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249 procedure Splice_Subtree
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250 (Target : in out Tree;
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251 Parent : Cursor;
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252 Before : Cursor;
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253 Source : in out Tree;
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254 Position : in out Cursor);
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255
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256 procedure Splice_Subtree
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257 (Container : in out Tree;
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258 Parent : Cursor;
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259 Before : Cursor;
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260 Position : Cursor);
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261
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262 procedure Splice_Children
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263 (Target : in out Tree;
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264 Target_Parent : Cursor;
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265 Before : Cursor;
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266 Source : in out Tree;
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267 Source_Parent : Cursor);
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268
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269 procedure Splice_Children
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270 (Container : in out Tree;
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271 Target_Parent : Cursor;
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272 Before : Cursor;
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273 Source_Parent : Cursor);
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274
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275 function Parent (Position : Cursor) return Cursor;
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276
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277 function First_Child (Parent : Cursor) return Cursor;
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278
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279 function First_Child_Element (Parent : Cursor) return Element_Type;
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280
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281 function Last_Child (Parent : Cursor) return Cursor;
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282
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283 function Last_Child_Element (Parent : Cursor) return Element_Type;
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284
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285 function Next_Sibling (Position : Cursor) return Cursor;
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286
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287 function Previous_Sibling (Position : Cursor) return Cursor;
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288
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289 procedure Next_Sibling (Position : in out Cursor);
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290
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291 procedure Previous_Sibling (Position : in out Cursor);
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292
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293 -- This version of the AI:
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294 -- 10-06-02 AI05-0136-1/07
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295 -- declares Iterate_Children this way:
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296 --
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297 -- procedure Iterate_Children
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298 -- (Container : Tree;
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299 -- Parent : Cursor;
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300 -- Process : not null access procedure (Position : Cursor));
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301 --
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302 -- It seems that the Container parameter is there by mistake, but we need
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303 -- an official ruling from the ARG. ???
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304
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305 procedure Iterate_Children
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306 (Parent : Cursor;
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307 Process : not null access procedure (Position : Cursor));
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308
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309 procedure Reverse_Iterate_Children
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310 (Parent : Cursor;
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311 Process : not null access procedure (Position : Cursor));
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312
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313 private
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314 -- A node of this multiway tree comprises an element and a list of children
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315 -- (that are themselves trees). The root node is distinguished because it
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316 -- contains only children: it does not have an element itself.
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317
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318 -- This design feature puts two design goals in tension with one another:
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319 -- (1) treat the root node the same as any other node
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320 -- (2) not declare any objects of type Element_Type unnecessarily
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321
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322 -- To satisfy (1), we could simply declare the Root node of the tree
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323 -- using the normal Tree_Node_Type, but that would mean that (2) is not
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324 -- satisfied. To resolve the tension (in favor of (2)), we declare the
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325 -- component Root as having a different node type, without an Element
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326 -- component (thus satisfying goal (2)) but otherwise identical to a normal
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327 -- node, and then use Unchecked_Conversion to convert an access object
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328 -- designating the Root node component to the access type designating a
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329 -- normal, non-root node (thus satisfying goal (1)). We make an explicit
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330 -- check for Root when there is any attempt to manipulate the Element
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331 -- component of the node (a check required by the RM anyway).
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332
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333 -- In order to be explicit about node (and pointer) representation, we
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334 -- specify that the respective node types have convention C, to ensure
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335 -- that the layout of the components of the node records is the same,
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336 -- thus guaranteeing that (unchecked) conversions between access types
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337 -- designating each kind of node type is a meaningful conversion.
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338
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339 use Ada.Containers.Helpers;
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340 package Implementation is new Generic_Implementation;
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341 use Implementation;
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342
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343 type Tree_Node_Type;
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344 type Tree_Node_Access is access all Tree_Node_Type;
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345 pragma Convention (C, Tree_Node_Access);
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346 pragma No_Strict_Aliasing (Tree_Node_Access);
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347 -- The above-mentioned Unchecked_Conversion is a violation of the normal
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348 -- aliasing rules.
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349
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350 type Children_Type is record
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351 First : Tree_Node_Access;
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352 Last : Tree_Node_Access;
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353 end record;
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354
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355 -- See the comment above. This declaration must exactly match the
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356 -- declaration of Root_Node_Type (except for the Element component).
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357
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358 type Tree_Node_Type is record
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359 Parent : Tree_Node_Access;
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360 Prev : Tree_Node_Access;
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361 Next : Tree_Node_Access;
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362 Children : Children_Type;
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363 Element : aliased Element_Type;
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364 end record;
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365 pragma Convention (C, Tree_Node_Type);
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366
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367 -- See the comment above. This declaration must match the declaration of
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368 -- Tree_Node_Type (except for the Element component).
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369
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370 type Root_Node_Type is record
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371 Parent : Tree_Node_Access;
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372 Prev : Tree_Node_Access;
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373 Next : Tree_Node_Access;
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374 Children : Children_Type;
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375 end record;
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376 pragma Convention (C, Root_Node_Type);
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377
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378 for Root_Node_Type'Alignment use Standard'Maximum_Alignment;
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379 -- The alignment has to be large enough to allow Root_Node to Tree_Node
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380 -- access value conversions, and Tree_Node_Type's alignment may be bumped
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381 -- up by the Element component.
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382
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383 use Ada.Finalization;
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384
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385 -- The Count component of type Tree represents the number of nodes that
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386 -- have been (dynamically) allocated. It does not include the root node
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387 -- itself. As implementors, we decide to cache this value, so that the
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388 -- selector function Node_Count can execute in O(1) time, in order to be
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389 -- consistent with the behavior of the Length selector function for other
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390 -- standard container library units. This does mean, however, that the
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391 -- two-container forms for Splice_XXX (that move subtrees across tree
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392 -- containers) will execute in O(n) time, because we must count the number
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393 -- of nodes in the subtree(s) that get moved. (We resolve the tension
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394 -- between Node_Count and Splice_XXX in favor of Node_Count, under the
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395 -- assumption that Node_Count is the more common operation).
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396
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397 type Tree is new Controlled with record
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398 Root : aliased Root_Node_Type;
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399 TC : aliased Tamper_Counts;
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400 Count : Count_Type := 0;
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401 end record;
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402
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403 overriding procedure Adjust (Container : in out Tree);
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404
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405 overriding procedure Finalize (Container : in out Tree) renames Clear;
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406
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407 use Ada.Streams;
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408
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409 procedure Write
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410 (Stream : not null access Root_Stream_Type'Class;
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411 Container : Tree);
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412
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413 for Tree'Write use Write;
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414
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415 procedure Read
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416 (Stream : not null access Root_Stream_Type'Class;
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417 Container : out Tree);
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418
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419 for Tree'Read use Read;
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420
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421 type Tree_Access is access all Tree;
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422 for Tree_Access'Storage_Size use 0;
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423
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424 type Cursor is record
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425 Container : Tree_Access;
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426 Node : Tree_Node_Access;
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427 end record;
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428
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429 procedure Write
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430 (Stream : not null access Root_Stream_Type'Class;
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431 Position : Cursor);
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432
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433 for Cursor'Write use Write;
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434
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435 procedure Read
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436 (Stream : not null access Root_Stream_Type'Class;
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437 Position : out Cursor);
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438
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439 for Cursor'Read use Read;
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440
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441 subtype Reference_Control_Type is Implementation.Reference_Control_Type;
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442 -- It is necessary to rename this here, so that the compiler can find it
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443
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444 type Constant_Reference_Type
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445 (Element : not null access constant Element_Type) is
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446 record
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447 Control : Reference_Control_Type :=
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448 raise Program_Error with "uninitialized reference";
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449 -- The RM says, "The default initialization of an object of
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450 -- type Constant_Reference_Type or Reference_Type propagates
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451 -- Program_Error."
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452 end record;
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453
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454 procedure Read
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455 (Stream : not null access Root_Stream_Type'Class;
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456 Item : out Constant_Reference_Type);
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457
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458 for Constant_Reference_Type'Read use Read;
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459
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460 procedure Write
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461 (Stream : not null access Root_Stream_Type'Class;
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462 Item : Constant_Reference_Type);
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463
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464 for Constant_Reference_Type'Write use Write;
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465
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466 type Reference_Type
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467 (Element : not null access Element_Type) is
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468 record
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469 Control : Reference_Control_Type :=
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470 raise Program_Error with "uninitialized reference";
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471 -- The RM says, "The default initialization of an object of
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472 -- type Constant_Reference_Type or Reference_Type propagates
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473 -- Program_Error."
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474 end record;
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475
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476 procedure Read
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477 (Stream : not null access Root_Stream_Type'Class;
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478 Item : out Reference_Type);
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479
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480 for Reference_Type'Read use Read;
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481
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482 procedure Write
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483 (Stream : not null access Root_Stream_Type'Class;
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484 Item : Reference_Type);
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485
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486 for Reference_Type'Write use Write;
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487
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488 -- Three operations are used to optimize in the expansion of "for ... of"
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489 -- loops: the Next(Cursor) procedure in the visible part, and the following
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490 -- Pseudo_Reference and Get_Element_Access functions. See Exp_Ch5 for
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491 -- details.
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492
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493 function Pseudo_Reference
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494 (Container : aliased Tree'Class) return Reference_Control_Type;
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495 pragma Inline (Pseudo_Reference);
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496 -- Creates an object of type Reference_Control_Type pointing to the
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497 -- container, and increments the Lock. Finalization of this object will
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498 -- decrement the Lock.
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499
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500 type Element_Access is access all Element_Type with
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501 Storage_Size => 0;
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502
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503 function Get_Element_Access
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504 (Position : Cursor) return not null Element_Access;
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505 -- Returns a pointer to the element designated by Position.
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506
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507 Empty_Tree : constant Tree := (Controlled with others => <>);
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508
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509 No_Element : constant Cursor := (others => <>);
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510
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511 end Ada.Containers.Multiway_Trees;
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