130 lines
6.5 KiB
Ada
130 lines
6.5 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S Y S T E M . V A L _ U N S --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2015, Free Software Foundation, Inc. --
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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 contains routines for scanning modular Unsigned
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-- values for use in Text_IO.Modular_IO, and the Value attribute.
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with System.Unsigned_Types;
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package System.Val_Uns is
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pragma Pure;
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function Scan_Raw_Unsigned
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(Str : String;
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Ptr : not null access Integer;
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Max : Integer) return System.Unsigned_Types.Unsigned;
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-- This function scans the string starting at Str (Ptr.all) for a valid
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-- integer according to the syntax described in (RM 3.5(43)). The substring
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-- scanned extends no further than Str (Max). Note: this does not scan
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-- leading or trailing blanks, nor leading sign.
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--
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-- There are three cases for the return:
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--
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-- If a valid integer is found, then Ptr.all is updated past the last
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-- character of the integer.
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--
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-- If no valid integer is found, then Ptr.all points either to an initial
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-- non-digit character, or to Max + 1 if the field is all spaces and the
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-- exception Constraint_Error is raised.
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--
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-- If a syntactically valid integer is scanned, but the value is out of
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-- range, or, in the based case, the base value is out of range or there
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-- is an out of range digit, then Ptr.all points past the integer, and
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-- Constraint_Error is raised.
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--
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-- Note: these rules correspond to the requirements for leaving the pointer
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-- positioned in Text_IO.Get. Note that the rules as stated in the RM would
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-- seem to imply that for a case like:
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--
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-- 8#12345670009#
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--
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-- the pointer should be left at the first # having scanned out the longest
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-- valid integer literal (8), but in fact in this case the pointer points
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-- past the final # and Constraint_Error is raised. This is the behavior
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-- expected for Text_IO and enforced by the ACATS tests.
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--
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-- If a based literal is malformed in that a character other than a valid
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-- hexadecimal digit is encountered during scanning out the digits after
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-- the # (this includes the case of using the wrong terminator, : instead
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-- of # or vice versa) there are two cases. If all the digits before the
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-- non-digit are in range of the base, as in
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--
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-- 8#100x00#
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-- 8#100:
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--
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-- then in this case, the "base" value before the initial # is returned as
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-- the result, and the pointer points to the initial # character on return.
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--
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-- If an out of range digit has been detected before the invalid character,
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-- as in:
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--
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-- 8#900x00#
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-- 8#900:
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--
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-- then the pointer is also left at the initial # character, but constraint
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-- error is raised reflecting the encounter of an out of range digit.
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--
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-- Finally if we have an unterminated fixed-point constant where the final
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-- # or : character is missing, Constraint_Error is raised and the pointer
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-- is left pointing past the last digit, as in:
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--
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-- 8#22
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--
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-- This string results in a Constraint_Error with the pointer pointing
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-- past the second 2.
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--
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-- Note: if Str is empty, i.e. if Max is less than Ptr, then this is a
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-- special case of an all-blank string, and Ptr is unchanged, and hence
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-- is greater than Max as required in this case.
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--
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-- Note: this routine should not be called with Str'Last = Positive'Last.
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-- If this occurs Program_Error is raised with a message noting that this
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-- case is not supported. Most such cases are eliminated by the caller.
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function Scan_Unsigned
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(Str : String;
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Ptr : not null access Integer;
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Max : Integer) return System.Unsigned_Types.Unsigned;
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-- Same as Scan_Raw_Unsigned, except scans optional leading
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-- blanks, and an optional leading plus sign.
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--
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-- Note: if a minus sign is present, Constraint_Error will be raised.
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-- Note: trailing blanks are not scanned.
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function Value_Unsigned
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(Str : String) return System.Unsigned_Types.Unsigned;
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-- Used in computing X'Value (Str) where X is a modular integer type whose
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-- modulus does not exceed the range of System.Unsigned_Types.Unsigned. Str
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-- is the string argument of the attribute. Constraint_Error is raised if
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-- the string is malformed, or if the value is out of range.
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end System.Val_Uns;
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