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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 -- G N A T . S P I T B O L --
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6 -- --
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7 -- S p e c --
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8 -- --
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9 -- Copyright (C) 1997-2017, AdaCore --
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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 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- SPITBOL-like interface facilities
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33
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34 -- This package provides a set of interfaces to semantic operations copied
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35 -- from SPITBOL, including a complete implementation of SPITBOL pattern
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36 -- matching. The code is derived from the original SPITBOL MINIMAL sources,
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37 -- created by Robert Dewar. The translation is not exact, but the
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38 -- algorithmic approaches are similar.
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39
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40 with Ada.Finalization; use Ada.Finalization;
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41 with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
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42 with Interfaces; use Interfaces;
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43
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44 package GNAT.Spitbol is
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45 pragma Preelaborate;
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46
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47 -- The Spitbol package relies heavily on the Unbounded_String package,
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48 -- using the synonym VString for variable length string. The following
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49 -- declarations define this type and other useful abbreviations.
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50
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51 subtype VString is Ada.Strings.Unbounded.Unbounded_String;
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52
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53 function V (Source : String) return VString
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54 renames Ada.Strings.Unbounded.To_Unbounded_String;
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55
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56 function S (Source : VString) return String
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57 renames Ada.Strings.Unbounded.To_String;
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58
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59 Nul : VString renames Ada.Strings.Unbounded.Null_Unbounded_String;
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60
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61 -------------------------
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62 -- Facilities Provided --
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63 -------------------------
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64
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65 -- The SPITBOL support in GNAT consists of this package together with
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66 -- several child packages. In this package, we have first a set of
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67 -- useful string functions, copied exactly from the corresponding
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68 -- SPITBOL functions, except that we had to rename REVERSE because
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69 -- reverse is a reserved word (it is now Reverse_String).
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70
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71 -- The second element of the parent package is a generic implementation
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72 -- of a table facility. In SPITBOL, the TABLE function allows general
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73 -- mappings from any datatype to any other datatype, and of course, as
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74 -- always, we can freely mix multiple types in the same table.
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75
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76 -- The Ada version of tables is strongly typed, so the indexing type and
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77 -- the range type are always of a consistent type. In this implementation
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78 -- we only provide VString as an indexing type, since this is by far the
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79 -- most common case. The generic instantiation specifies the range type
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80 -- to be used.
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81
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82 -- Three child packages provide standard instantiations of this table
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83 -- package for three common datatypes:
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84
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85 -- GNAT.Spitbol.Table_Boolean (file g-sptabo.ads)
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86
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87 -- The range type is Boolean. The default value is False. This
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88 -- means that this table is essentially a representation of a set.
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89
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90 -- GNAT.Spitbol.Table_Integer (file g-sptain.ads)
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91
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92 -- The range type is Integer. The default value is Integer'First.
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93 -- This provides a general mapping from strings to integers.
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94
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95 -- GNAT.Spitbol.Table_VString (file g-sptavs.ads)
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96
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97 -- The range type is VString. The default value is the null string.
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98 -- This provides a general mapping from strings to strings.
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99
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100 -- Finally there is another child package:
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101
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102 -- GNAT.Spitbol.Patterns (file g-spipat.ads)
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103
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104 -- This child package provides a complete implementation of SPITBOL
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105 -- pattern matching. The spec contains a complete tutorial on the
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106 -- use of pattern matching.
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107
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108 ---------------------------------
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109 -- Standard String Subprograms --
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110 ---------------------------------
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111
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112 -- This section contains some operations on unbounded strings that are
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113 -- closely related to those in the package Unbounded.Strings, but they
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114 -- correspond to the SPITBOL semantics for these operations.
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115
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116 function Char (Num : Natural) return Character;
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117 pragma Inline (Char);
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118 -- Equivalent to Character'Val (Num)
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119
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120 function Lpad
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121 (Str : VString;
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122 Len : Natural;
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123 Pad : Character := ' ') return VString;
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124 function Lpad
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125 (Str : String;
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126 Len : Natural;
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127 Pad : Character := ' ') return VString;
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128 -- If the length of Str is greater than or equal to Len, then Str is
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129 -- returned unchanged. Otherwise, The value returned is obtained by
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130 -- concatenating Length (Str) - Len instances of the Pad character to
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131 -- the left hand side.
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132
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133 procedure Lpad
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134 (Str : in out VString;
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135 Len : Natural;
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136 Pad : Character := ' ');
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137 -- The procedure form is identical to the function form, except that
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138 -- the result overwrites the input argument Str.
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139
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140 function Reverse_String (Str : VString) return VString;
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141 function Reverse_String (Str : String) return VString;
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142 -- Returns result of reversing the string Str, i.e. the result returned
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143 -- is a mirror image (end-for-end reversal) of the input string.
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144
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145 procedure Reverse_String (Str : in out VString);
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146 -- The procedure form is identical to the function form, except that the
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147 -- result overwrites the input argument Str.
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148
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149 function Rpad
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150 (Str : VString;
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151 Len : Natural;
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152 Pad : Character := ' ') return VString;
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153 function Rpad
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154 (Str : String;
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155 Len : Natural;
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156 Pad : Character := ' ') return VString;
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157 -- If the length of Str is greater than or equal to Len, then Str is
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158 -- returned unchanged. Otherwise, The value returned is obtained by
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159 -- concatenating Length (Str) - Len instances of the Pad character to
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160 -- the right hand side.
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161
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162 procedure Rpad
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163 (Str : in out VString;
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164 Len : Natural;
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165 Pad : Character := ' ');
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166 -- The procedure form is identical to the function form, except that the
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167 -- result overwrites the input argument Str.
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168
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169 function Size (Source : VString) return Natural
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170 renames Ada.Strings.Unbounded.Length;
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171
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172 function Substr
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173 (Str : VString;
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174 Start : Positive;
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175 Len : Natural) return VString;
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176 function Substr
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177 (Str : String;
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178 Start : Positive;
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179 Len : Natural) return VString;
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180 -- Returns the substring starting at the given character position (which
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181 -- is always counted from the start of the string, regardless of bounds,
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182 -- e.g. 2 means starting with the second character of the string), and
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183 -- with the length (Len) given. Index_Error is raised if the starting
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184 -- position is out of range, and Length_Error is raised if Len is too long.
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185
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186 function Trim (Str : VString) return VString;
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187 function Trim (Str : String) return VString;
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188 -- Returns the string obtained by removing all spaces from the right
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189 -- hand side of the string Str.
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190
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191 procedure Trim (Str : in out VString);
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192 -- The procedure form is identical to the function form, except that the
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193 -- result overwrites the input argument Str.
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194
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195 -----------------------
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196 -- Utility Functions --
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197 -----------------------
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198
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199 -- In SPITBOL, integer values can be freely treated as strings. The
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200 -- following definitions help provide some of this capability in
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201 -- some common cases.
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202
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203 function "&" (Num : Integer; Str : String) return String;
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204 function "&" (Str : String; Num : Integer) return String;
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205 function "&" (Num : Integer; Str : VString) return VString;
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206 function "&" (Str : VString; Num : Integer) return VString;
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207 -- In all these concatenation operations, the integer is converted to
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208 -- its corresponding decimal string form, with no leading blank.
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209
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210 function S (Num : Integer) return String;
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211 function V (Num : Integer) return VString;
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212 -- These operators return the given integer converted to its decimal
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213 -- string form with no leading blank.
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214
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215 function N (Str : VString) return Integer;
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216 -- Converts string to number (same as Integer'Value (S (Str)))
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217
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218 -------------------
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219 -- Table Support --
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220 -------------------
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221
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222 -- So far, we only provide support for tables whose indexing data values
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223 -- are strings (or unbounded strings). The values stored may be of any
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224 -- type, as supplied by the generic formal parameter.
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225
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226 generic
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227
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228 type Value_Type is private;
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229 -- Any non-limited type can be used as the value type in the table
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230
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231 Null_Value : Value_Type;
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232 -- Value used to represent a value that is not present in the table
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233
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234 with function Img (A : Value_Type) return String;
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235 -- Used to provide image of value in Dump procedure
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236
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237 with function "=" (A, B : Value_Type) return Boolean is <>;
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238 -- This allows a user-defined equality function to override the
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239 -- predefined equality function.
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240
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241 package Table is
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242
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243 ------------------------
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244 -- Table Declarations --
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245 ------------------------
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246
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247 type Table (N : Unsigned_32) is private;
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248 -- This is the table type itself. A table is a mapping from string
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249 -- values to values of Value_Type. The discriminant is an estimate of
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250 -- the number of values in the table. If the estimate is much too
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251 -- high, some space is wasted, if the estimate is too low, access to
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252 -- table elements is slowed down. The type Table has copy semantics,
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253 -- not reference semantics. This means that if a table is copied
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254 -- using simple assignment, then the two copies refer to entirely
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255 -- separate tables.
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256
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257 -----------------------------
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258 -- Table Access Operations --
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259 -----------------------------
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260
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261 function Get (T : Table; Name : VString) return Value_Type;
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262 function Get (T : Table; Name : Character) return Value_Type;
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263 pragma Inline (Get);
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264 function Get (T : Table; Name : String) return Value_Type;
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265
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266 -- If an entry with the given name exists in the table, then the
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267 -- corresponding Value_Type value is returned. Otherwise Null_Value
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268 -- is returned.
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269
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270 function Present (T : Table; Name : VString) return Boolean;
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271 function Present (T : Table; Name : Character) return Boolean;
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272 pragma Inline (Present);
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273 function Present (T : Table; Name : String) return Boolean;
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274 -- Determines if an entry with the given name is present in the table.
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275 -- A returned value of True means that it is in the table, otherwise
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276 -- False indicates that it is not in the table.
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277
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278 procedure Delete (T : in out Table; Name : VString);
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279 procedure Delete (T : in out Table; Name : Character);
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280 pragma Inline (Delete);
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281 procedure Delete (T : in out Table; Name : String);
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282 -- Deletes the table element with the given name from the table. If
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283 -- no element in the table has this name, then the call has no effect.
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284
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285 procedure Set (T : in out Table; Name : VString; Value : Value_Type);
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286 procedure Set (T : in out Table; Name : Character; Value : Value_Type);
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287 pragma Inline (Set);
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288 procedure Set (T : in out Table; Name : String; Value : Value_Type);
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289 -- Sets the value of the element with the given name to the given
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290 -- value. If Value is equal to Null_Value, the effect is to remove
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291 -- the entry from the table. If no element with the given name is
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292 -- currently in the table, then a new element with the given value
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293 -- is created.
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294
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295 ----------------------------
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296 -- Allocation and Copying --
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297 ----------------------------
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298
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299 -- Table is a controlled type, so that all storage associated with
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300 -- tables is properly reclaimed when a Table value is abandoned.
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301 -- Tables have value semantics rather than reference semantics as
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302 -- in Spitbol, i.e. when you assign a copy you end up with two
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303 -- distinct copies of the table, as though COPY had been used in
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304 -- Spitbol. It seems clearly more appropriate in Ada to require
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305 -- the use of explicit pointers for reference semantics.
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306
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307 procedure Clear (T : in out Table);
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308 -- Clears all the elements of the given table, freeing associated
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309 -- storage. On return T is an empty table with no elements.
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310
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311 procedure Copy (From : Table; To : in out Table);
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312 -- First all the elements of table To are cleared (as described for
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313 -- the Clear procedure above), then all the elements of table From
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314 -- are copied into To. In the case where the tables From and To have
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315 -- the same declared size (i.e. the same discriminant), the call to
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316 -- Copy has the same effect as the assignment of From to To. The
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317 -- difference is that, unlike the assignment statement, which will
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318 -- cause a Constraint_Error if the source and target are of different
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319 -- sizes, Copy works fine with different sized tables.
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320
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321 ----------------
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322 -- Conversion --
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323 ----------------
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324
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325 type Table_Entry is record
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326 Name : VString;
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327 Value : Value_Type;
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328 end record;
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329
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330 type Table_Array is array (Positive range <>) of Table_Entry;
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331
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332 function Convert_To_Array (T : Table) return Table_Array;
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333 -- Returns a Table_Array value with a low bound of 1, and a length
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334 -- corresponding to the number of elements in the table. The elements
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335 -- of the array give the elements of the table in unsorted order.
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336
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337 ---------------
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338 -- Debugging --
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339 ---------------
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340
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341 procedure Dump (T : Table; Str : String := "Table");
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342 -- Dump contents of given table to the standard output file. The
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343 -- string value Str is used as the name of the table in the dump.
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344
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345 procedure Dump (T : Table_Array; Str : String := "Table_Array");
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346 -- Dump contents of given table array to the current output file. The
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347 -- string value Str is used as the name of the table array in the dump.
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348
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349 private
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350
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351 ------------------
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352 -- Private Part --
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353 ------------------
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354
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355 -- A Table is a pointer to a hash table which contains the indicated
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356 -- number of hash elements (the number is forced to the next odd value
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357 -- if it is even to improve hashing performance). If more than one
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358 -- of the entries in a table hashes to the same slot, the Next field
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359 -- is used to chain entries from the header. The chains are not kept
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360 -- ordered. A chain is terminated by a null pointer in Next. An unused
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361 -- chain is marked by an element whose Name is null and whose value
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362 -- is Null_Value.
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363
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364 type Hash_Element;
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365 type Hash_Element_Ptr is access all Hash_Element;
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366
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367 type Hash_Element is record
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368 Name : String_Access := null;
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369 Value : Value_Type := Null_Value;
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370 Next : Hash_Element_Ptr := null;
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371 end record;
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372
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373 type Hash_Table is
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374 array (Unsigned_32 range <>) of aliased Hash_Element;
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375
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376 type Table (N : Unsigned_32) is new Controlled with record
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377 Elmts : Hash_Table (1 .. N);
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378 end record;
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379
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380 pragma Finalize_Storage_Only (Table);
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381
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382 overriding procedure Adjust (Object : in out Table);
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383 -- The Adjust procedure does a deep copy of the table structure
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384 -- so that the effect of assignment is, like other assignments
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385 -- in Ada, value-oriented.
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386
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387 overriding procedure Finalize (Object : in out Table);
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388 -- This is the finalization routine that ensures that all storage
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389 -- associated with a table is properly released when a table object
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390 -- is abandoned and finalized.
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391
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392 end Table;
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393
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394 end GNAT.Spitbol;
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