Line data    Source code

       1              : // Copyright 2026 The Authors
       2              : //
       3              : // Licensed under the Apache License, Version 2.0 (the "License");
       4              : // you may not use this file except in compliance with the License.
       5              : // You may obtain a copy of the License at
       6              : //
       7              : //      https://www.apache.org/licenses/LICENSE-2.0
       8              : //
       9              : // Unless required by applicable law or agreed to in writing, software
      10              : // distributed under the License is distributed on an "AS IS" BASIS,
      11              : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12              : // See the License for the specific language governing permissions and
      13              : // limitations under the License.
      14              : 
      15              : import 'package:characters/characters.dart';
      16              : 
      17              : /// Handle a string made up of hexidecimal characters (not witchcraft)
      18              : class HexString {
      19              :   static const hexValues = {
      20              :     '0',
      21              :     '1',
      22              :     '2',
      23              :     '3',
      24              :     '4',
      25              :     '5',
      26              :     '6',
      27              :     '7',
      28              :     '8',
      29              :     '9',
      30              :     'a',
      31              :     'b',
      32              :     'c',
      33              :     'd',
      34              :     'e',
      35              :     'f',
      36              :     'A',
      37              :     'B',
      38              :     'C',
      39              :     'D',
      40              :     'E',
      41              :     'F',
      42              :   };
      43              : 
      44              :   final String value;
      45              : 
      46            1 :   HexString._(this.value);
      47              : 
      48            1 :   static HexString? tryParse(String input) {
      49              :     String test;
      50            1 :     if (input.startsWith('0x')) {
      51            1 :       test = input.substring(2);
      52              :     } else {
      53              :       test = input;
      54              :     }
      55            2 :     for (var c in test.characters) {
      56            1 :       if (!hexValues.contains(c)) {
      57              :         return null;
      58              :       }
      59              :     }
      60            1 :     return HexString._(input);
      61              :   }
      62              : 
      63            2 :   static bool isValid(String value) => tryParse(value) != null;
      64              : 
      65            1 :   static int unHex(int c) {
      66            4 :     if ('0'.codeUnitAt(0) <= c && c <= '9'.codeUnitAt(0)) {
      67            2 :       return c - '0'.codeUnitAt(0);
      68              :     }
      69            4 :     if ('a'.codeUnitAt(0) <= c && c <= 'f'.codeUnitAt(0)) {
      70            3 :       return c - 'a'.codeUnitAt(0) + 10;
      71              :     }
      72            4 :     if ('A'.codeUnitAt(0) <= c && c <= 'F'.codeUnitAt(0)) {
      73            3 :       return c - 'A'.codeUnitAt(0) + 10;
      74              :     }
      75              :     return 0;
      76              :   }
      77              : }