mirror of
https://github.com/dart-lang/sdk
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a75ffc8956
This is practically a copy of the change in https://dart-review.googlesource.com/c/sdk/+/118040 but applied to the non-nnbd sdk. Even though there is no intent to run the non-nnbd sdk with the non-nullable experiment, we need to add this annotation because of how we intend to gradually start testing NNBD. The libraries.json under sdk_nnbd is allowed to point to libraries under the non-nnbd sdk in order to temporarily build without errors until all patch files are migrated and all CFE issues are addressed. Change-Id: I53c1123a8d86c10695832a8a0ad35adb7b4d92fd Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/125181 Commit-Queue: Sigmund Cherem <sigmund@google.com> Reviewed-by: Bob Nystrom <rnystrom@google.com>
559 lines
20 KiB
Dart
559 lines
20 KiB
Dart
// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// @dart = 2.6
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part of dart.convert;
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/// The Unicode Replacement character `U+FFFD` (<28>).
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const int unicodeReplacementCharacterRune = 0xFFFD;
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/// The Unicode Byte Order Marker (BOM) character `U+FEFF`.
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const int unicodeBomCharacterRune = 0xFEFF;
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/// An instance of the default implementation of the [Utf8Codec].
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///
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/// This instance provides a convenient access to the most common UTF-8
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/// use cases.
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///
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/// Examples:
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///
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/// var encoded = utf8.encode("Îñţérñåţîöñåļîžåţîờñ");
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/// var decoded = utf8.decode([0x62, 0x6c, 0xc3, 0xa5, 0x62, 0xc3, 0xa6,
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/// 0x72, 0x67, 0x72, 0xc3, 0xb8, 0x64]);
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const Utf8Codec utf8 = Utf8Codec();
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/// A [Utf8Codec] encodes strings to utf-8 code units (bytes) and decodes
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/// UTF-8 code units to strings.
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class Utf8Codec extends Encoding {
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final bool _allowMalformed;
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/// Instantiates a new [Utf8Codec].
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///
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/// The optional [allowMalformed] argument defines how [decoder] (and [decode])
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/// deal with invalid or unterminated character sequences.
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///
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/// If it is `true` (and not overridden at the method invocation) [decode] and
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/// the [decoder] replace invalid (or unterminated) octet
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/// sequences with the Unicode Replacement character `U+FFFD` (<28>). Otherwise
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/// they throw a [FormatException].
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const Utf8Codec({bool allowMalformed = false})
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: _allowMalformed = allowMalformed;
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/// The name of this codec, "utf-8".
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String get name => "utf-8";
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/// Decodes the UTF-8 [codeUnits] (a list of unsigned 8-bit integers) to the
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/// corresponding string.
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///
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/// If the [codeUnits] start with the encoding of a
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/// [unicodeBomCharacterRune], that character is discarded.
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///
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/// If [allowMalformed] is `true` the decoder replaces invalid (or
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/// unterminated) character sequences with the Unicode Replacement character
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/// `U+FFFD` (<28>). Otherwise it throws a [FormatException].
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///
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/// If [allowMalformed] is not given, it defaults to the `allowMalformed` that
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/// was used to instantiate `this`.
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String decode(List<int> codeUnits, {bool allowMalformed}) {
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allowMalformed ??= _allowMalformed;
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return Utf8Decoder(allowMalformed: allowMalformed).convert(codeUnits);
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}
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Utf8Encoder get encoder => const Utf8Encoder();
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Utf8Decoder get decoder {
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return Utf8Decoder(allowMalformed: _allowMalformed);
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}
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}
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/// This class converts strings to their UTF-8 code units (a list of
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/// unsigned 8-bit integers).
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class Utf8Encoder extends Converter<String, List<int>> {
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const Utf8Encoder();
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/// Converts [string] to its UTF-8 code units (a list of
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/// unsigned 8-bit integers).
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///
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/// If [start] and [end] are provided, only the substring
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/// `string.substring(start, end)` is converted.
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Uint8List convert(String string, [int start = 0, int end]) {
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var stringLength = string.length;
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end = RangeError.checkValidRange(start, end, stringLength);
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var length = end - start;
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if (length == 0) return Uint8List(0);
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// Create a new encoder with a length that is guaranteed to be big enough.
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// A single code unit uses at most 3 bytes, a surrogate pair at most 4.
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var encoder = _Utf8Encoder.withBufferSize(length * 3);
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var endPosition = encoder._fillBuffer(string, start, end);
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assert(endPosition >= end - 1);
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if (endPosition != end) {
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// Encoding skipped the last code unit.
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// That can only happen if the last code unit is a leadsurrogate.
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// Force encoding of the lead surrogate by itself.
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var lastCodeUnit = string.codeUnitAt(end - 1);
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assert(_isLeadSurrogate(lastCodeUnit));
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// We use a non-surrogate as `nextUnit` so that _writeSurrogate just
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// writes the lead-surrogate.
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var wasCombined = encoder._writeSurrogate(lastCodeUnit, 0);
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assert(!wasCombined);
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}
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return encoder._buffer.sublist(0, encoder._bufferIndex);
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}
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/// Starts a chunked conversion.
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///
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/// The converter works more efficiently if the given [sink] is a
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/// [ByteConversionSink].
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StringConversionSink startChunkedConversion(Sink<List<int>> sink) {
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return _Utf8EncoderSink(
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sink is ByteConversionSink ? sink : ByteConversionSink.from(sink));
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}
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// Override the base-classes bind, to provide a better type.
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Stream<List<int>> bind(Stream<String> stream) => super.bind(stream);
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}
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/// This class encodes Strings to UTF-8 code units (unsigned 8 bit integers).
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// TODO(floitsch): make this class public.
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class _Utf8Encoder {
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int _carry = 0;
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int _bufferIndex = 0;
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final Uint8List _buffer;
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static const _DEFAULT_BYTE_BUFFER_SIZE = 1024;
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_Utf8Encoder() : this.withBufferSize(_DEFAULT_BYTE_BUFFER_SIZE);
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_Utf8Encoder.withBufferSize(int bufferSize)
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: _buffer = _createBuffer(bufferSize);
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/// Allow an implementation to pick the most efficient way of storing bytes.
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static Uint8List _createBuffer(int size) => Uint8List(size);
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/// Tries to combine the given [leadingSurrogate] with the [nextCodeUnit] and
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/// writes it to [_buffer].
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///
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/// Returns true if the [nextCodeUnit] was combined with the
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/// [leadingSurrogate]. If it wasn't then nextCodeUnit was not a trailing
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/// surrogate and has not been written yet.
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///
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/// It is safe to pass 0 for [nextCodeUnit] in which case only the leading
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/// surrogate is written.
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bool _writeSurrogate(int leadingSurrogate, int nextCodeUnit) {
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if (_isTailSurrogate(nextCodeUnit)) {
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var rune = _combineSurrogatePair(leadingSurrogate, nextCodeUnit);
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// If the rune is encoded with 2 code-units then it must be encoded
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// with 4 bytes in UTF-8.
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assert(rune > _THREE_BYTE_LIMIT);
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assert(rune <= _FOUR_BYTE_LIMIT);
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_buffer[_bufferIndex++] = 0xF0 | (rune >> 18);
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_buffer[_bufferIndex++] = 0x80 | ((rune >> 12) & 0x3f);
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_buffer[_bufferIndex++] = 0x80 | ((rune >> 6) & 0x3f);
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_buffer[_bufferIndex++] = 0x80 | (rune & 0x3f);
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return true;
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} else {
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// TODO(floitsch): allow to throw on malformed strings.
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// Encode the half-surrogate directly into UTF-8. This yields
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// invalid UTF-8, but we started out with invalid UTF-16.
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// Surrogates are always encoded in 3 bytes in UTF-8.
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_buffer[_bufferIndex++] = 0xE0 | (leadingSurrogate >> 12);
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_buffer[_bufferIndex++] = 0x80 | ((leadingSurrogate >> 6) & 0x3f);
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_buffer[_bufferIndex++] = 0x80 | (leadingSurrogate & 0x3f);
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return false;
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}
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}
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/// Fills the [_buffer] with as many characters as possible.
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///
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/// Does not encode any trailing lead-surrogate. This must be done by the
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/// caller.
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///
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/// Returns the position in the string. The returned index points to the
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/// first code unit that hasn't been encoded.
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int _fillBuffer(String str, int start, int end) {
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if (start != end && _isLeadSurrogate(str.codeUnitAt(end - 1))) {
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// Don't handle a trailing lead-surrogate in this loop. The caller has
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// to deal with those.
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end--;
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}
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int stringIndex;
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for (stringIndex = start; stringIndex < end; stringIndex++) {
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var codeUnit = str.codeUnitAt(stringIndex);
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// ASCII has the same representation in UTF-8 and UTF-16.
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if (codeUnit <= _ONE_BYTE_LIMIT) {
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if (_bufferIndex >= _buffer.length) break;
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_buffer[_bufferIndex++] = codeUnit;
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} else if (_isLeadSurrogate(codeUnit)) {
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if (_bufferIndex + 3 >= _buffer.length) break;
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// Note that it is safe to read the next code unit. We decremented
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// [end] above when the last valid code unit was a leading surrogate.
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var nextCodeUnit = str.codeUnitAt(stringIndex + 1);
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var wasCombined = _writeSurrogate(codeUnit, nextCodeUnit);
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if (wasCombined) stringIndex++;
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} else {
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var rune = codeUnit;
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if (rune <= _TWO_BYTE_LIMIT) {
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if (_bufferIndex + 1 >= _buffer.length) break;
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_buffer[_bufferIndex++] = 0xC0 | (rune >> 6);
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_buffer[_bufferIndex++] = 0x80 | (rune & 0x3f);
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} else {
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assert(rune <= _THREE_BYTE_LIMIT);
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if (_bufferIndex + 2 >= _buffer.length) break;
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_buffer[_bufferIndex++] = 0xE0 | (rune >> 12);
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_buffer[_bufferIndex++] = 0x80 | ((rune >> 6) & 0x3f);
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_buffer[_bufferIndex++] = 0x80 | (rune & 0x3f);
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}
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}
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}
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return stringIndex;
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}
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}
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/// This class encodes chunked strings to UTF-8 code units (unsigned 8-bit
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/// integers).
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class _Utf8EncoderSink extends _Utf8Encoder with StringConversionSinkMixin {
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final ByteConversionSink _sink;
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_Utf8EncoderSink(this._sink);
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void close() {
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if (_carry != 0) {
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// addSlice will call close again, but then the carry must be equal to 0.
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addSlice("", 0, 0, true);
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return;
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}
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_sink.close();
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}
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void addSlice(String str, int start, int end, bool isLast) {
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_bufferIndex = 0;
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if (start == end && !isLast) {
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return;
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}
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if (_carry != 0) {
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var nextCodeUnit = 0;
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if (start != end) {
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nextCodeUnit = str.codeUnitAt(start);
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} else {
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assert(isLast);
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}
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var wasCombined = _writeSurrogate(_carry, nextCodeUnit);
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// Either we got a non-empty string, or we must not have been combined.
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assert(!wasCombined || start != end);
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if (wasCombined) start++;
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_carry = 0;
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}
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do {
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start = _fillBuffer(str, start, end);
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var isLastSlice = isLast && (start == end);
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if (start == end - 1 && _isLeadSurrogate(str.codeUnitAt(start))) {
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if (isLast && _bufferIndex < _buffer.length - 3) {
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// There is still space for the last incomplete surrogate.
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// We use a non-surrogate as second argument. This way the
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// function will just add the surrogate-half to the buffer.
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var hasBeenCombined = _writeSurrogate(str.codeUnitAt(start), 0);
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assert(!hasBeenCombined);
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} else {
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// Otherwise store it in the carry. If isLast is true, then
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// close will flush the last carry.
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_carry = str.codeUnitAt(start);
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}
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start++;
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}
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_sink.addSlice(_buffer, 0, _bufferIndex, isLastSlice);
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_bufferIndex = 0;
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} while (start < end);
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if (isLast) close();
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}
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// TODO(floitsch): implement asUtf8Sink. Sligthly complicated because it
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// needs to deal with malformed input.
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}
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/// This class converts UTF-8 code units (lists of unsigned 8-bit integers)
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/// to a string.
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class Utf8Decoder extends Converter<List<int>, String> {
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final bool _allowMalformed;
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/// Instantiates a new [Utf8Decoder].
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///
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/// The optional [allowMalformed] argument defines how [convert] deals
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/// with invalid or unterminated character sequences.
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///
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/// If it is `true` [convert] replaces invalid (or unterminated) character
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/// sequences with the Unicode Replacement character `U+FFFD` (<28>). Otherwise
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/// it throws a [FormatException].
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const Utf8Decoder({bool allowMalformed = false})
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: _allowMalformed = allowMalformed;
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/// Converts the UTF-8 [codeUnits] (a list of unsigned 8-bit integers) to the
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/// corresponding string.
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///
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/// Uses the code units from [start] to, but no including, [end].
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/// If [end] is omitted, it defaults to `codeUnits.length`.
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///
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/// If the [codeUnits] start with the encoding of a
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/// [unicodeBomCharacterRune], that character is discarded.
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String convert(List<int> codeUnits, [int start = 0, int end]) {
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// Allow the implementation to intercept and specialize based on the type
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// of codeUnits.
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var result = _convertIntercepted(_allowMalformed, codeUnits, start, end);
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if (result != null) {
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return result;
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}
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var length = codeUnits.length;
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end = RangeError.checkValidRange(start, end, length);
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// Fast case for ASCII strings avoids StringBuffer/_Utf8Decoder.
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int oneBytes = _scanOneByteCharacters(codeUnits, start, end);
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StringBuffer buffer;
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bool isFirstCharacter = true;
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if (oneBytes > 0) {
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var firstPart = String.fromCharCodes(codeUnits, start, start + oneBytes);
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start += oneBytes;
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if (start == end) {
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return firstPart;
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}
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buffer = StringBuffer(firstPart);
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isFirstCharacter = false;
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}
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buffer ??= StringBuffer();
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var decoder = _Utf8Decoder(buffer, _allowMalformed);
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decoder._isFirstCharacter = isFirstCharacter;
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decoder.convert(codeUnits, start, end);
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decoder.flush(codeUnits, end);
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return buffer.toString();
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}
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/// Starts a chunked conversion.
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///
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/// The converter works more efficiently if the given [sink] is a
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/// [StringConversionSink].
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ByteConversionSink startChunkedConversion(Sink<String> sink) {
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StringConversionSink stringSink;
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if (sink is StringConversionSink) {
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stringSink = sink;
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} else {
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stringSink = StringConversionSink.from(sink);
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}
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return stringSink.asUtf8Sink(_allowMalformed);
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}
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// Override the base-classes bind, to provide a better type.
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Stream<String> bind(Stream<List<int>> stream) => super.bind(stream);
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external Converter<List<int>, T> fuse<T>(Converter<String, T> next);
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external static String _convertIntercepted(
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bool allowMalformed, List<int> codeUnits, int start, int end);
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}
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// UTF-8 constants.
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const int _ONE_BYTE_LIMIT = 0x7f; // 7 bits
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const int _TWO_BYTE_LIMIT = 0x7ff; // 11 bits
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const int _THREE_BYTE_LIMIT = 0xffff; // 16 bits
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const int _FOUR_BYTE_LIMIT = 0x10ffff; // 21 bits, truncated to Unicode max.
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// UTF-16 constants.
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const int _SURROGATE_TAG_MASK = 0xFC00;
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const int _SURROGATE_VALUE_MASK = 0x3FF;
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const int _LEAD_SURROGATE_MIN = 0xD800;
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const int _TAIL_SURROGATE_MIN = 0xDC00;
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bool _isLeadSurrogate(int codeUnit) =>
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(codeUnit & _SURROGATE_TAG_MASK) == _LEAD_SURROGATE_MIN;
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bool _isTailSurrogate(int codeUnit) =>
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(codeUnit & _SURROGATE_TAG_MASK) == _TAIL_SURROGATE_MIN;
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int _combineSurrogatePair(int lead, int tail) =>
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0x10000 + ((lead & _SURROGATE_VALUE_MASK) << 10) |
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(tail & _SURROGATE_VALUE_MASK);
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/// Decodes UTF-8.
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///
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/// The decoder handles chunked input.
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// TODO(floitsch): make this class public.
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class _Utf8Decoder {
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final bool _allowMalformed;
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final StringSink _stringSink;
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bool _isFirstCharacter = true;
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int _value = 0;
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int _expectedUnits = 0;
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int _extraUnits = 0;
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_Utf8Decoder(this._stringSink, this._allowMalformed);
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bool get hasPartialInput => _expectedUnits > 0;
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// Limits of one through four byte encodings.
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static const List<int> _LIMITS = <int>[
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_ONE_BYTE_LIMIT,
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_TWO_BYTE_LIMIT,
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_THREE_BYTE_LIMIT,
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_FOUR_BYTE_LIMIT
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];
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void close() {
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flush();
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}
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/// Flushes this decoder as if closed.
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///
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/// This method throws if the input was partial and the decoder was
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/// constructed with `allowMalformed` set to `false`.
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///
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/// The [source] and [offset] of the current position may be provided,
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/// and are included in the exception if one is thrown.
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void flush([List<int> source, int offset]) {
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if (hasPartialInput) {
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if (!_allowMalformed) {
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throw FormatException(
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"Unfinished UTF-8 octet sequence", source, offset);
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}
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_stringSink.writeCharCode(unicodeReplacementCharacterRune);
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_value = 0;
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_expectedUnits = 0;
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_extraUnits = 0;
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}
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}
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void convert(List<int> codeUnits, int startIndex, int endIndex) {
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var value = _value;
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var expectedUnits = _expectedUnits;
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var extraUnits = _extraUnits;
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_value = 0;
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_expectedUnits = 0;
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_extraUnits = 0;
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var i = startIndex;
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loop:
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while (true) {
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multibyte:
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if (expectedUnits > 0) {
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do {
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if (i == endIndex) {
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break loop;
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}
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var unit = codeUnits[i];
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if ((unit & 0xC0) != 0x80) {
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expectedUnits = 0;
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if (!_allowMalformed) {
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throw FormatException(
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"Bad UTF-8 encoding 0x${unit.toRadixString(16)}",
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codeUnits,
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i);
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}
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_isFirstCharacter = false;
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_stringSink.writeCharCode(unicodeReplacementCharacterRune);
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break multibyte;
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} else {
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value = (value << 6) | (unit & 0x3f);
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expectedUnits--;
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i++;
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}
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||
} while (expectedUnits > 0);
|
||
if (value <= _LIMITS[extraUnits - 1]) {
|
||
// Overly long encoding. The value could be encoded with a shorter
|
||
// encoding.
|
||
if (!_allowMalformed) {
|
||
throw FormatException(
|
||
"Overlong encoding of 0x${value.toRadixString(16)}",
|
||
codeUnits,
|
||
i - extraUnits - 1);
|
||
}
|
||
expectedUnits = extraUnits = 0;
|
||
value = unicodeReplacementCharacterRune;
|
||
}
|
||
if (value > _FOUR_BYTE_LIMIT) {
|
||
if (!_allowMalformed) {
|
||
throw FormatException(
|
||
"Character outside valid Unicode range: "
|
||
"0x${value.toRadixString(16)}",
|
||
codeUnits,
|
||
i - extraUnits - 1);
|
||
}
|
||
value = unicodeReplacementCharacterRune;
|
||
}
|
||
if (!_isFirstCharacter || value != unicodeBomCharacterRune) {
|
||
_stringSink.writeCharCode(value);
|
||
}
|
||
_isFirstCharacter = false;
|
||
}
|
||
|
||
while (i < endIndex) {
|
||
var oneBytes = _scanOneByteCharacters(codeUnits, i, endIndex);
|
||
if (oneBytes > 0) {
|
||
_isFirstCharacter = false;
|
||
assert(i + oneBytes <= endIndex);
|
||
_stringSink.write(String.fromCharCodes(codeUnits, i, i + oneBytes));
|
||
|
||
i += oneBytes;
|
||
if (i == endIndex) break;
|
||
}
|
||
var unit = codeUnits[i++];
|
||
// TODO(floitsch): the way we test we could potentially allow
|
||
// units that are too large, if they happen to have the
|
||
// right bit-pattern. (Same is true for the multibyte loop above).
|
||
// TODO(floitsch): optimize this loop. See:
|
||
// https://codereview.chromium.org/22929022/diff/1/sdk/lib/convert/utf.dart?column_width=80
|
||
if (unit < 0) {
|
||
// TODO(floitsch): should this be unit <= 0 ?
|
||
if (!_allowMalformed) {
|
||
throw FormatException(
|
||
"Negative UTF-8 code unit: -0x${(-unit).toRadixString(16)}",
|
||
codeUnits,
|
||
i - 1);
|
||
}
|
||
_stringSink.writeCharCode(unicodeReplacementCharacterRune);
|
||
} else {
|
||
assert(unit > _ONE_BYTE_LIMIT);
|
||
if ((unit & 0xE0) == 0xC0) {
|
||
value = unit & 0x1F;
|
||
expectedUnits = extraUnits = 1;
|
||
continue loop;
|
||
}
|
||
if ((unit & 0xF0) == 0xE0) {
|
||
value = unit & 0x0F;
|
||
expectedUnits = extraUnits = 2;
|
||
continue loop;
|
||
}
|
||
// 0xF5, 0xF6 ... 0xFF never appear in valid UTF-8 sequences.
|
||
if ((unit & 0xF8) == 0xF0 && unit < 0xF5) {
|
||
value = unit & 0x07;
|
||
expectedUnits = extraUnits = 3;
|
||
continue loop;
|
||
}
|
||
if (!_allowMalformed) {
|
||
throw FormatException(
|
||
"Bad UTF-8 encoding 0x${unit.toRadixString(16)}",
|
||
codeUnits,
|
||
i - 1);
|
||
}
|
||
value = unicodeReplacementCharacterRune;
|
||
expectedUnits = extraUnits = 0;
|
||
_isFirstCharacter = false;
|
||
_stringSink.writeCharCode(value);
|
||
}
|
||
}
|
||
break loop;
|
||
}
|
||
if (expectedUnits > 0) {
|
||
_value = value;
|
||
_expectedUnits = expectedUnits;
|
||
_extraUnits = extraUnits;
|
||
}
|
||
}
|
||
}
|
||
|
||
// Returns the number of bytes in [units] starting at offset [from] which have
|
||
// the leftmost bit set to 0.
|
||
//
|
||
// To increase performance of this critical method we have a special variant of
|
||
// it implemented in the VM's patch files, which is why we make it external.
|
||
external int _scanOneByteCharacters(List<int> units, int from, int endIndex);
|