75 lines
4.3 KiB
Ada
75 lines
4.3 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 _ R E A L --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2014, 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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package System.Val_Real is
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pragma Pure;
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function Scan_Real
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(Str : String;
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Ptr : not null access Integer;
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Max : Integer) return Long_Long_Float;
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-- This function scans the string starting at Str (Ptr.all) for a valid
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-- real literal according to the syntax described in (RM 3.5(43)). The
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-- substring scanned extends no further than Str (Max). There are three
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-- cases for the return:
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--
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-- If a valid real is found after scanning past any initial spaces, then
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-- Ptr.all is updated past the last character of the real (but trailing
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-- spaces are not scanned out).
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--
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-- If no valid real is found, then Ptr.all points either to an initial
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-- non-blank 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 real 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 real literal,
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-- and Constraint_Error is raised.
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--
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-- Note: these rules correspond to the requirements for leaving the
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-- pointer positioned in Text_Io.Get
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--
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-- Note: if Str is null, 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 Value_Real (Str : String) return Long_Long_Float;
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-- Used in computing X'Value (Str) where X is a floating-point type or an
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-- ordinary fixed-point type. Str is the string argument of the attribute.
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-- Constraint_Error is raised if the string is malformed, or if the value
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-- out of range of Long_Long_Float.
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end System.Val_Real;
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