77 lines
2.2 KiB
Dart
77 lines
2.2 KiB
Dart
// Copyright (c) 2023, Sudipto Chandra
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// All rights reserved. Check LICENSE file for details.
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import 'dart:typed_data';
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import 'codecs/base64.dart';
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Base64Codec _codecFromParameters({
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bool url = false,
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bool padding = false,
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}) {
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if (url && padding) {
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return Base64Codec.urlSafe;
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} else if (url) {
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return Base64Codec.urlSafeNoPadding;
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} else if (padding) {
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return Base64Codec.standard;
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} else {
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return Base64Codec.standardNoPadding;
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}
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}
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const _codecsWithPadding = {
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Base64Codec.standard,
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Base64Codec.urlSafe,
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};
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/// Converts 8-bit integer sequence to 6-bit Base-64 character sequence.
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///
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/// Parameters:
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/// - [input] is a sequence of 8-bit integers
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/// - If [url] is true, URL and Filename-safe alphabet is used.
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/// - If [padding] is true, the output will have padding characters.
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/// - [codec] is the [Base64Codec] to use. It is derived from the other
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/// parameters if not provided.
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String toBase64(
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List<int> input, {
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Base64Codec? codec,
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bool url = false,
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bool padding = true,
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}) {
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codec ??= _codecFromParameters(
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url: url,
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padding: padding,
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);
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Iterable<int> out = codec.encoder.convert(input);
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if (!padding && _codecsWithPadding.contains(codec)) {
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out = out.takeWhile((x) => x != codec!.encoder.padding);
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}
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return String.fromCharCodes(out);
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}
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/// Converts 6-bit Base-64 character sequence to 8-bit integer sequence.
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///
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/// Parameters:
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/// - [input] should be a valid base-64 encoded string.
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/// - If [padding] is true, the output will have padding characters.
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/// - [codec] is the [Base64Codec] to use. It is derived from the other
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/// parameters if not provided.
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///
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/// Throws:
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/// - [FormatException] if the [input] contains invalid characters, and the
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/// length is not valid for a base-64 encoded string.
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///
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/// This implementation can handle both the original and URL/filename-safe
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/// alphabets. Any letters appearing after the first padding character is
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/// observed are ignored. If a partial string is detected, the following bits
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/// are assumed to be zeros.
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Uint8List fromBase64(
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String input, {
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Base64Codec? codec,
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bool padding = true,
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}) {
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codec ??= _codecFromParameters(padding: padding);
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var out = codec.decoder.convert(input.codeUnits);
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return Uint8List.fromList(out);
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}
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