83 lines
4.7 KiB
Ada
83 lines
4.7 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- G N A T . E X C E P T I O N S --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2000-2010, AdaCore --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides an interface for raising predefined exceptions
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-- with an exception message. It can be used from Pure units.
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-- There is no prohibition in Ada that prevents exceptions being raised
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-- from within pure units. The raise statement is perfectly acceptable.
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-- However, it is not normally possible to raise an exception with a
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-- message because the routine Ada.Exceptions.Raise_Exception is not in
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-- a Pure unit. This is an annoying and unnecessary restriction and this
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-- package allows for raising the standard predefined exceptions at least.
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package GNAT.Exceptions is
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pragma Pure;
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type Exception_Type is limited null record;
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-- Type used to specify which exception to raise
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-- Really Exception_Type is Exception_Id, but Exception_Id can't be
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-- used directly since it is declared in the non-pure unit Ada.Exceptions,
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-- Exception_Id is in fact simply a pointer to the type Exception_Data
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-- declared in System.Standard_Library (which is also non-pure). So what
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-- we do is to define it here as a by reference type (any by reference
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-- type would do), and then Import the definitions from Standard_Library.
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-- Since this is a by reference type, these will be passed by reference,
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-- which has the same effect as passing a pointer.
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-- This type is not private because keeping it by reference would require
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-- defining it in a way (e.g a tagged type) that would drag other run time
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-- files, which is unwanted in the case of e.g ravenscar where we want to
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-- minimize the number of run time files needed by default.
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CE : constant Exception_Type; -- Constraint_Error
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PE : constant Exception_Type; -- Program_Error
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SE : constant Exception_Type; -- Storage_Error
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TE : constant Exception_Type; -- Tasking_Error
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-- One of these constants is used in the call to specify the exception
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procedure Raise_Exception (E : Exception_Type; Message : String);
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pragma Import (Ada, Raise_Exception, "__gnat_raise_exception");
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pragma No_Return (Raise_Exception);
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-- Raise specified exception with specified message
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private
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pragma Import (C, CE, "constraint_error");
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pragma Import (C, PE, "program_error");
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pragma Import (C, SE, "storage_error");
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pragma Import (C, TE, "tasking_error");
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-- References to the exception structures in the standard library
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end GNAT.Exceptions;
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