| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- S Y S T E M . V A L U E _ R -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 2020-2021, 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 real values for use in |
| -- Text_IO.Decimal_IO, Fixed_IO, Float_IO and the Value attribute. |
| |
| with System.Unsigned_Types; use System.Unsigned_Types; |
| |
| generic |
| |
| type Uns is mod <>; |
| |
| Precision_Limit : Uns; |
| |
| Round : Boolean; |
| |
| package System.Value_R is |
| pragma Preelaborate; |
| |
| function Scan_Raw_Real |
| (Str : String; |
| Ptr : not null access Integer; |
| Max : Integer; |
| Base : out Unsigned; |
| Scale : out Integer; |
| Extra : out Unsigned; |
| Minus : out Boolean) return Uns; |
| -- This function scans the string starting at Str (Ptr.all) for a valid |
| -- real literal according to the syntax described in (RM 3.5(43)). The |
| -- substring scanned extends no further than Str (Max). There are three |
| -- cases for the return: |
| -- |
| -- If a valid real is found after scanning past any initial spaces, then |
| -- Ptr.all is updated past the last character of the real (but trailing |
| -- spaces are not scanned out) and the Base, Scale, Extra and Minus out |
| -- parameters are set; if Val is the result of the call, then the real |
| -- represented by the literal is equal to |
| -- |
| -- (Val * Base + Extra) * (Base ** (Scale - 1)) |
| -- |
| -- with the negative sign if Minus is true. |
| -- |
| -- If no valid real is found, then Ptr.all points either to an initial |
| -- non-blank character, or to Max + 1 if the field is all spaces and the |
| -- exception Constraint_Error is raised. |
| -- |
| -- If a syntactically valid real 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 real literal, |
| -- and Constraint_Error is raised. |
| -- |
| -- Note: these rules correspond to the requirements for leaving the |
| -- pointer positioned in Text_Io.Get |
| -- |
| -- Note: if Str is null, 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 Value_Raw_Real |
| (Str : String; |
| Base : out Unsigned; |
| Scale : out Integer; |
| Extra : out Unsigned; |
| Minus : out Boolean) return Uns; |
| -- Used in computing X'Value (Str) where X is a real type. Str is the |
| -- string argument of the attribute. Constraint_Error is raised if the |
| -- string is malformed. |
| |
| end System.Value_R; |
