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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 -- G N A T . E X C E P T I O N S --
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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) 2000-2018, AdaCore --
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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 provides an interface for raising predefined exceptions
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33 -- with an exception message. It can be used from Pure units.
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34
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35 -- There is no prohibition in Ada that prevents exceptions being raised
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36 -- from within pure units. The raise statement is perfectly acceptable.
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37
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38 -- However, it is not normally possible to raise an exception with a
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39 -- message because the routine Ada.Exceptions.Raise_Exception is not in
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40 -- a Pure unit. This is an annoying and unnecessary restriction and this
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41 -- package allows for raising the standard predefined exceptions at least.
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42
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43 package GNAT.Exceptions is
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44 pragma Pure;
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45
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46 type Exception_Type is limited null record;
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47 -- Type used to specify which exception to raise
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48
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49 -- Really Exception_Type is Exception_Id, but Exception_Id can't be
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50 -- used directly since it is declared in the non-pure unit Ada.Exceptions,
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51
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52 -- Exception_Id is in fact simply a pointer to the type Exception_Data
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53 -- declared in System.Standard_Library (which is also non-pure). So what
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54 -- we do is to define it here as a by reference type (any by reference
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55 -- type would do), and then Import the definitions from Standard_Library.
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56 -- Since this is a by reference type, these will be passed by reference,
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57 -- which has the same effect as passing a pointer.
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58
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59 -- This type is not private because keeping it by reference would require
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60 -- defining it in a way (e.g. using a tagged type) that would drag in other
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61 -- run-time files, which is unwanted in the case of e.g. Ravenscar where we
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62 -- want to minimize the number of run-time files needed by default.
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63
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64 CE : constant Exception_Type; -- Constraint_Error
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65 PE : constant Exception_Type; -- Program_Error
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66 SE : constant Exception_Type; -- Storage_Error
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67 TE : constant Exception_Type; -- Tasking_Error
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68 -- One of these constants is used in the call to specify the exception
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69
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70 procedure Raise_Exception (E : Exception_Type; Message : String);
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71 pragma Import (Ada, Raise_Exception, "__gnat_raise_exception");
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72 pragma No_Return (Raise_Exception);
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73 -- Raise specified exception with specified message
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74
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75 private
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76 pragma Import (C, CE, "constraint_error");
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77 pragma Import (C, PE, "program_error");
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78 pragma Import (C, SE, "storage_error");
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79 pragma Import (C, TE, "tasking_error");
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80 -- References to the exception structures in the standard library
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81
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82 end GNAT.Exceptions;
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