1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S Y S T E M . V A L U E _ U -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2020, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26-- -- 27-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32-- This package contains routines for scanning modular Unsigned 33-- values for use in Text_IO.Modular_IO, and the Value attribute. 34 35generic 36 37 type Uns is mod <>; 38 39package System.Value_U is 40 pragma Preelaborate; 41 42 function Scan_Raw_Unsigned 43 (Str : String; 44 Ptr : not null access Integer; 45 Max : Integer) return Uns; 46 -- This function scans the string starting at Str (Ptr.all) for a valid 47 -- integer according to the syntax described in (RM 3.5(43)). The substring 48 -- scanned extends no further than Str (Max). Note: this does not scan 49 -- leading or trailing blanks, nor leading sign. 50 -- 51 -- There are three cases for the return: 52 -- 53 -- If a valid integer is found, then Ptr.all is updated past the last 54 -- character of the integer. 55 -- 56 -- If no valid integer is found, then Ptr.all points either to an initial 57 -- non-digit character, or to Max + 1 if the field is all spaces and the 58 -- exception Constraint_Error is raised. 59 -- 60 -- If a syntactically valid integer is scanned, but the value is out of 61 -- range, or, in the based case, the base value is out of range or there 62 -- is an out of range digit, then Ptr.all points past the integer, and 63 -- Constraint_Error is raised. 64 -- 65 -- Note: these rules correspond to the requirements for leaving the pointer 66 -- positioned in Text_IO.Get. Note that the rules as stated in the RM would 67 -- seem to imply that for a case like: 68 -- 69 -- 8#12345670009# 70 -- 71 -- the pointer should be left at the first # having scanned out the longest 72 -- valid integer literal (8), but in fact in this case the pointer points 73 -- past the final # and Constraint_Error is raised. This is the behavior 74 -- expected for Text_IO and enforced by the ACATS tests. 75 -- 76 -- If a based literal is malformed in that a character other than a valid 77 -- hexadecimal digit is encountered during scanning out the digits after 78 -- the # (this includes the case of using the wrong terminator, : instead 79 -- of # or vice versa) there are two cases. If all the digits before the 80 -- non-digit are in range of the base, as in 81 -- 82 -- 8#100x00# 83 -- 8#100: 84 -- 85 -- then in this case, the "base" value before the initial # is returned as 86 -- the result, and the pointer points to the initial # character on return. 87 -- 88 -- If an out of range digit has been detected before the invalid character, 89 -- as in: 90 -- 91 -- 8#900x00# 92 -- 8#900: 93 -- 94 -- then the pointer is also left at the initial # character, but constraint 95 -- error is raised reflecting the encounter of an out of range digit. 96 -- 97 -- Finally if we have an unterminated fixed-point constant where the final 98 -- # or : character is missing, Constraint_Error is raised and the pointer 99 -- is left pointing past the last digit, as in: 100 -- 101 -- 8#22 102 -- 103 -- This string results in a Constraint_Error with the pointer pointing 104 -- past the second 2. 105 -- 106 -- Note: if Str is empty, i.e. if Max is less than Ptr, then this is a 107 -- special case of an all-blank string, and Ptr is unchanged, and hence 108 -- is greater than Max as required in this case. 109 -- 110 -- Note: this routine should not be called with Str'Last = Positive'Last. 111 -- If this occurs Program_Error is raised with a message noting that this 112 -- case is not supported. Most such cases are eliminated by the caller. 113 114 function Scan_Unsigned 115 (Str : String; 116 Ptr : not null access Integer; 117 Max : Integer) return Uns; 118 -- Same as Scan_Raw_Unsigned, except scans optional leading 119 -- blanks, and an optional leading plus sign. 120 -- 121 -- Note: if a minus sign is present, Constraint_Error will be raised. 122 -- Note: trailing blanks are not scanned. 123 124 function Value_Unsigned 125 (Str : String) return Uns; 126 -- Used in computing X'Value (Str) where X is a modular integer type whose 127 -- modulus does not exceed the range of System.Unsigned_Types.Unsigned. Str 128 -- is the string argument of the attribute. Constraint_Error is raised if 129 -- the string is malformed, or if the value is out of range. 130 131end System.Value_U; 132