| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- S Y S T E M . V A L U E _ U -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1992-2021, Free Software Foundation, Inc. -- |
| -- -- |
| -- GNAT is free software; you can redistribute it and/or modify it under -- |
| -- terms of the GNU General Public License as published by the Free Soft- -- |
| -- ware Foundation; either version 3, or (at your option) any later ver- -- |
| -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- This package contains routines for scanning modular Unsigned |
| -- values for use in Text_IO.Modular_IO, and the Value attribute. |
| |
| generic |
| |
| type Uns is mod <>; |
| |
| package System.Value_U is |
| pragma Preelaborate; |
| |
| function Scan_Raw_Unsigned |
| (Str : String; |
| Ptr : not null access Integer; |
| Max : Integer) return Uns; |
| -- This function scans the string starting at Str (Ptr.all) for a valid |
| -- integer according to the syntax described in (RM 3.5(43)). The substring |
| -- scanned extends no further than Str (Max). Note: this does not scan |
| -- leading or trailing blanks, nor leading sign. |
| -- |
| -- There are three cases for the return: |
| -- |
| -- If a valid integer is found, then Ptr.all is updated past the last |
| -- character of the integer. |
| -- |
| -- If no valid integer is found, then Ptr.all points either to an initial |
| -- non-digit character, or to Max + 1 if the field is all spaces and the |
| -- exception Constraint_Error is raised. |
| -- |
| -- If a syntactically valid integer is scanned, but the value is out of |
| -- range, or, in the based case, the base value is out of range or there |
| -- is an out of range digit, then Ptr.all points past the integer, and |
| -- Constraint_Error is raised. |
| -- |
| -- Note: these rules correspond to the requirements for leaving the pointer |
| -- positioned in Text_IO.Get. Note that the rules as stated in the RM would |
| -- seem to imply that for a case like: |
| -- |
| -- 8#12345670009# |
| -- |
| -- the pointer should be left at the first # having scanned out the longest |
| -- valid integer literal (8), but in fact in this case the pointer points |
| -- past the final # and Constraint_Error is raised. This is the behavior |
| -- expected for Text_IO and enforced by the ACATS tests. |
| -- |
| -- If a based literal is malformed in that a character other than a valid |
| -- hexadecimal digit is encountered during scanning out the digits after |
| -- the # (this includes the case of using the wrong terminator, : instead |
| -- of # or vice versa) there are two cases. If all the digits before the |
| -- non-digit are in range of the base, as in |
| -- |
| -- 8#100x00# |
| -- 8#100: |
| -- |
| -- then in this case, the "base" value before the initial # is returned as |
| -- the result, and the pointer points to the initial # character on return. |
| -- |
| -- If an out of range digit has been detected before the invalid character, |
| -- as in: |
| -- |
| -- 8#900x00# |
| -- 8#900: |
| -- |
| -- then the pointer is also left at the initial # character, but constraint |
| -- error is raised reflecting the encounter of an out of range digit. |
| -- |
| -- Finally if we have an unterminated fixed-point constant where the final |
| -- # or : character is missing, Constraint_Error is raised and the pointer |
| -- is left pointing past the last digit, as in: |
| -- |
| -- 8#22 |
| -- |
| -- This string results in a Constraint_Error with the pointer pointing |
| -- past the second 2. |
| -- |
| -- Note: if Str is empty, i.e. if Max is less than Ptr, then this is a |
| -- special case of an all-blank string, and Ptr is unchanged, and hence |
| -- is greater than Max as required in this case. |
| -- |
| -- Note: this routine should not be called with Str'Last = Positive'Last. |
| -- If this occurs Program_Error is raised with a message noting that this |
| -- case is not supported. Most such cases are eliminated by the caller. |
| |
| function Scan_Unsigned |
| (Str : String; |
| Ptr : not null access Integer; |
| Max : Integer) return Uns; |
| -- Same as Scan_Raw_Unsigned, except scans optional leading |
| -- blanks, and an optional leading plus sign. |
| -- |
| -- Note: if a minus sign is present, Constraint_Error will be raised. |
| -- Note: trailing blanks are not scanned. |
| |
| function Value_Unsigned |
| (Str : String) return Uns; |
| -- Used in computing X'Value (Str) where X is a modular integer type whose |
| -- modulus does not exceed the range of System.Unsigned_Types.Unsigned. Str |
| -- is the string argument of the attribute. Constraint_Error is raised if |
| -- the string is malformed, or if the value is out of range. |
| |
| end System.Value_U; |
