68 lines
1.9 KiB
Dart
68 lines
1.9 KiB
Dart
import "dart:convert";
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import "dart:typed_data";
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const String _alphabet = "0123456789abcdef";
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/// An instance of the default implementation of the [HexCodec].
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const hex = HexCodec();
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/// A codec for encoding and decoding byte arrays to and from
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/// hexadecimal strings.
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class HexCodec extends Codec<List<int>, String> {
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const HexCodec();
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@override
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Converter<List<int>, String> get encoder => const HexEncoder();
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@override
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Converter<String, List<int>> get decoder => const HexDecoder();
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}
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/// A converter to encode byte arrays into hexadecimal strings.
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class HexEncoder extends Converter<List<int>, String> {
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/// If true, the encoder will encode into uppercase hexadecimal strings.
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final bool upperCase;
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const HexEncoder({this.upperCase = false});
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@override
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String convert(List<int> bytes) {
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StringBuffer buffer = StringBuffer();
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for (int part in bytes) {
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if (part & 0xff != part) {
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throw const FormatException("Non-byte integer detected");
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}
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buffer.write('${part < 16 ? '0' : ''}${part.toRadixString(16)}');
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}
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if (upperCase) {
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return buffer.toString().toUpperCase();
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} else {
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return buffer.toString();
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}
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}
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}
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/// A converter to decode hexadecimal strings into byte arrays.
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class HexDecoder extends Converter<String, List<int>> {
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const HexDecoder();
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@override
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List<int> convert(String hex) {
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String str = hex.replaceAll(" ", "");
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str = str.toLowerCase();
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if (str.length % 2 != 0) {
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str = "0" + str;
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}
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Uint8List result = Uint8List(str.length ~/ 2);
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for (int i = 0; i < result.length; i++) {
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int firstDigit = _alphabet.indexOf(str[i * 2]);
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int secondDigit = _alphabet.indexOf(str[i * 2 + 1]);
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if (firstDigit == -1 || secondDigit == -1) {
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throw FormatException("Non-hex character detected in $hex");
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}
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result[i] = (firstDigit << 4) + secondDigit;
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}
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return result;
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}
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}
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