Removed fixed dependencies

packages/convert/lib/src/hex/decoder.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library convert.hex.decoder;
+
+import 'dart:convert';
+import 'dart:typed_data';
+
+import '../utils.dart';
+
+/// The canonical instance of [HexDecoder].
+const hexDecoder = const HexDecoder._();
+
+/// A converter that decodes hexadecimal strings into byte arrays.
+///
+/// Because two hexadecimal digits correspond to a single byte, this will throw
+/// a [FormatException] if given an odd-length string. It will also throw a
+/// [FormatException] if given a string containing non-hexadecimal code units.
+class HexDecoder extends Converter<String, List<int>> {
+  const HexDecoder._();
+
+  List<int> convert(String string) {
+    if (!string.length.isEven) {
+      throw new FormatException("Invalid input length, must be even.",
+          string, string.length);
+    }
+
+    var bytes = new Uint8List(string.length ~/ 2);
+    _decode(string.codeUnits, 0, string.length, bytes, 0);
+    return bytes;
+  }
+
+  StringConversionSink startChunkedConversion(Sink<List<int>> sink) =>
+      new _HexDecoderSink(sink);
+}
+
+/// A conversion sink for chunked hexadecimal decoding.
+class _HexDecoderSink extends StringConversionSinkBase {
+  /// The underlying sink to which decoded byte arrays will be passed.
+  final Sink<List<int>> _sink;
+
+  /// The trailing digit from the previous string.
+  ///
+  /// This will be non-`null` if the most recent string had an odd number of
+  /// hexadecimal digits. Since it's the most significant digit, it's always a
+  /// multiple of 16.
+  int _lastDigit;
+
+  _HexDecoderSink(this._sink);
+
+  void addSlice(String string, int start, int end, bool isLast) {
+    RangeError.checkValidRange(start, end, string.length);
+
+    if (start == end) {
+      if (isLast) _close(string, end);
+      return;
+    }
+
+    var codeUnits = string.codeUnits;
+    Uint8List bytes;
+    int bytesStart;
+    if (_lastDigit == null) {
+      bytes = new Uint8List((end - start) ~/ 2);
+      bytesStart = 0;
+    } else {
+      var hexPairs = (end - start - 1) ~/ 2;
+      bytes = new Uint8List(1 + hexPairs);
+      bytes[0] = _lastDigit + digitForCodeUnit(codeUnits, start);
+      start++;
+      bytesStart = 1;
+    }
+
+    _lastDigit = _decode(codeUnits, start, end, bytes, bytesStart);
+
+    _sink.add(bytes);
+    if (isLast) _close(string, end);
+  }
+
+  ByteConversionSink asUtf8Sink(bool allowMalformed) =>
+      new _HexDecoderByteSink(_sink);
+
+  void close() => _close();
+
+  /// Like [close], but includes [string] and [index] in the [FormatException]
+  /// if one is thrown.
+  void _close([String string, int index]) {
+    if (_lastDigit != null) {
+      throw new FormatException(
+          "Input ended with incomplete encoded byte.", string, index);
+    }
+
+    _sink.close();
+  }
+}
+
+/// A conversion sink for chunked hexadecimal decoding from UTF-8 bytes.
+class _HexDecoderByteSink extends ByteConversionSinkBase {
+  /// The underlying sink to which decoded byte arrays will be passed.
+  final Sink<List<int>> _sink;
+
+  /// The trailing digit from the previous string.
+  ///
+  /// This will be non-`null` if the most recent string had an odd number of
+  /// hexadecimal digits. Since it's the most significant digit, it's always a
+  /// multiple of 16.
+  int _lastDigit;
+
+  _HexDecoderByteSink(this._sink);
+
+  void add(List<int> chunk) => addSlice(chunk, 0, chunk.length, false);
+
+  void addSlice(List<int> chunk, int start, int end, bool isLast) {
+    RangeError.checkValidRange(start, end, chunk.length);
+
+    if (start == end) {
+      if (isLast) _close(chunk, end);
+      return;
+    }
+
+    Uint8List bytes;
+    int bytesStart;
+    if (_lastDigit == null) {
+      bytes = new Uint8List((end - start) ~/ 2);
+      bytesStart = 0;
+    } else {
+      var hexPairs = (end - start - 1) ~/ 2;
+      bytes = new Uint8List(1 + hexPairs);
+      bytes[0] = _lastDigit + digitForCodeUnit(chunk, start);
+      start++;
+      bytesStart = 1;
+    }
+
+    _lastDigit = _decode(chunk, start, end, bytes, bytesStart);
+
+    _sink.add(bytes);
+    if (isLast) _close(chunk, end);
+  }
+
+  void close() => _close();
+
+  /// Like [close], but includes [chunk] and [index] in the [FormatException]
+  /// if one is thrown.
+  void _close([List<int> chunk, int index]) {
+    if (_lastDigit != null) {
+      throw new FormatException(
+          "Input ended with incomplete encoded byte.", chunk, index);
+    }
+
+    _sink.close();
+  }
+}
+
+/// Decodes [codeUnits] and writes the result into [destination].
+///
+/// This reads from [codeUnits] between [sourceStart] and [sourceEnd]. It writes
+/// the result into [destination] starting at [destinationStart].
+///
+/// If there's a leftover digit at the end of the decoding, this returns that
+/// digit. Otherwise it returns `null`.
+int _decode(List<int> codeUnits, int sourceStart, int sourceEnd,
+    List<int> destination, int destinationStart) {
+  var destinationIndex = destinationStart;
+  for (var i = sourceStart; i < sourceEnd - 1; i += 2) {
+    var firstDigit = digitForCodeUnit(codeUnits, i);
+    var secondDigit = digitForCodeUnit(codeUnits, i + 1);
+    destination[destinationIndex++] = 16 * firstDigit + secondDigit;
+  }
+
+  if ((sourceEnd - sourceStart).isEven) return null;
+  return 16 * digitForCodeUnit(codeUnits, sourceEnd - 1);
+}