1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S Y S T E M . V A L _ U N S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2015, 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 35with System.Unsigned_Types; 36 37package System.Val_Uns is 38 pragma Pure; 39 40 function Scan_Raw_Unsigned 41 (Str : String; 42 Ptr : not null access Integer; 43 Max : Integer) return System.Unsigned_Types.Unsigned; 44 -- This function scans the string starting at Str (Ptr.all) for a valid 45 -- integer according to the syntax described in (RM 3.5(43)). The substring 46 -- scanned extends no further than Str (Max). Note: this does not scan 47 -- leading or trailing blanks, nor leading sign. 48 -- 49 -- There are three cases for the return: 50 -- 51 -- If a valid integer is found, then Ptr.all is updated past the last 52 -- character of the integer. 53 -- 54 -- If no valid integer is found, then Ptr.all points either to an initial 55 -- non-digit character, or to Max + 1 if the field is all spaces and the 56 -- exception Constraint_Error is raised. 57 -- 58 -- If a syntactically valid integer is scanned, but the value is out of 59 -- range, or, in the based case, the base value is out of range or there 60 -- is an out of range digit, then Ptr.all points past the integer, and 61 -- Constraint_Error is raised. 62 -- 63 -- Note: these rules correspond to the requirements for leaving the pointer 64 -- positioned in Text_IO.Get. Note that the rules as stated in the RM would 65 -- seem to imply that for a case like: 66 -- 67 -- 8#12345670009# 68 -- 69 -- the pointer should be left at the first # having scanned out the longest 70 -- valid integer literal (8), but in fact in this case the pointer points 71 -- past the final # and Constraint_Error is raised. This is the behavior 72 -- expected for Text_IO and enforced by the ACATS tests. 73 -- 74 -- If a based literal is malformed in that a character other than a valid 75 -- hexadecimal digit is encountered during scanning out the digits after 76 -- the # (this includes the case of using the wrong terminator, : instead 77 -- of # or vice versa) there are two cases. If all the digits before the 78 -- non-digit are in range of the base, as in 79 -- 80 -- 8#100x00# 81 -- 8#100: 82 -- 83 -- then in this case, the "base" value before the initial # is returned as 84 -- the result, and the pointer points to the initial # character on return. 85 -- 86 -- If an out of range digit has been detected before the invalid character, 87 -- as in: 88 -- 89 -- 8#900x00# 90 -- 8#900: 91 -- 92 -- then the pointer is also left at the initial # character, but constraint 93 -- error is raised reflecting the encounter of an out of range digit. 94 -- 95 -- Finally if we have an unterminated fixed-point constant where the final 96 -- # or : character is missing, Constraint_Error is raised and the pointer 97 -- is left pointing past the last digit, as in: 98 -- 99 -- 8#22 100 -- 101 -- This string results in a Constraint_Error with the pointer pointing 102 -- past the second 2. 103 -- 104 -- Note: if Str is empty, i.e. if Max is less than Ptr, then this is a 105 -- special case of an all-blank string, and Ptr is unchanged, and hence 106 -- is greater than Max as required in this case. 107 -- 108 -- Note: this routine should not be called with Str'Last = Positive'Last. 109 -- If this occurs Program_Error is raised with a message noting that this 110 -- case is not supported. Most such cases are eliminated by the caller. 111 112 function Scan_Unsigned 113 (Str : String; 114 Ptr : not null access Integer; 115 Max : Integer) return System.Unsigned_Types.Unsigned; 116 -- Same as Scan_Raw_Unsigned, except scans optional leading 117 -- blanks, and an optional leading plus sign. 118 -- 119 -- Note: if a minus sign is present, Constraint_Error will be raised. 120 -- Note: trailing blanks are not scanned. 121 122 function Value_Unsigned 123 (Str : String) return System.Unsigned_Types.Unsigned; 124 -- Used in computing X'Value (Str) where X is a modular integer type whose 125 -- modulus does not exceed the range of System.Unsigned_Types.Unsigned. Str 126 -- is the string argument of the attribute. Constraint_Error is raised if 127 -- the string is malformed, or if the value is out of range. 128 129end System.Val_Uns; 130