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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME COMPONENTS --
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4 -- --
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5 -- S Y S T E M . V A L _ I N T --
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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) 1992-2018, 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 -- 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 -- This package contains routines for scanning signed Integer values for use
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33 -- in Text_IO.Integer_IO, and the Value attribute.
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34
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35 package System.Val_Int is
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36 pragma Pure;
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37
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38 function Scan_Integer
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39 (Str : String;
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40 Ptr : not null access Integer;
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41 Max : Integer) return Integer;
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42 -- This function scans the string starting at Str (Ptr.all) for a valid
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43 -- integer according to the syntax described in (RM 3.5(43)). The substring
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44 -- scanned extends no further than Str (Max). There are three cases for the
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45 -- return:
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46 --
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47 -- If a valid integer is found after scanning past any initial spaces, then
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48 -- Ptr.all is updated past the last character of the integer (but trailing
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49 -- spaces are not scanned out).
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50 --
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51 -- If no valid integer is found, then Ptr.all points either to an initial
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52 -- non-digit character, or to Max + 1 if the field is all spaces and the
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53 -- exception Constraint_Error is raised.
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54 --
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55 -- If a syntactically valid integer is scanned, but the value is out of
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56 -- range, or, in the based case, the base value is out of range or there
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57 -- is an out of range digit, then Ptr.all points past the integer, and
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58 -- Constraint_Error is raised.
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59 --
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60 -- Note: these rules correspond to the requirements for leaving the pointer
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61 -- positioned in Text_Io.Get
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62 --
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63 -- Note: if Str is null, i.e. if Max is less than Ptr, then this is a
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64 -- special case of an all-blank string, and Ptr is unchanged, and hence
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65 -- is greater than Max as required in this case.
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66
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67 function Value_Integer (Str : String) return Integer;
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68 -- Used in computing X'Value (Str) where X is a signed integer type whose
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69 -- base range does not exceed the base range of Integer. Str is the string
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70 -- argument of the attribute. Constraint_Error is raised if the string is
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71 -- malformed, or if the value is out of range.
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72
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73 end System.Val_Int;
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