81 lines
4.7 KiB
Ada
81 lines
4.7 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 _ D E C --
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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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-- This package contains routines for scanning decimal values where the size
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-- of the type is no greater than Standard.Integer'Size, for use in Text_IO.
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-- Decimal_IO, and the Value attribute for such decimal types.
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package System.Val_Dec is
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pragma Pure;
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function Scan_Decimal
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(Str : String;
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Ptr : not null access Integer;
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Max : Integer;
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Scale : Integer) return Integer;
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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 literal is found after scanning past any initial spaces,
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-- then Ptr.all is updated past the last character of the literal (but
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-- trailing spaces are not scanned out). The value returned is the value
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-- Integer'Integer_Value (decimal-literal-value), using the given Scale
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-- to determine this value.
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--
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-- If no valid real literal is found, then Ptr.all points either to an
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-- initial non-digit character, or to Max + 1 if the field is all spaces
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-- and the 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
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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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function Value_Decimal (Str : String; Scale : Integer) return Integer;
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-- Used in computing X'Value (Str) where X is a decimal fixed-point type
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-- whose size does not exceed Standard.Integer'Size. Str is the string
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-- argument of the attribute. Constraint_Error is raised if the string
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-- is malformed or if the value is out of range of Integer (not the
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-- range of the fixed-point type, that check must be done by the caller.
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-- Otherwise the value returned is the value Integer'Integer_Value
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-- (decimal-literal-value), using Scale to determine this value.
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end System.Val_Dec;
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