Utf16BytesToCodeUnitsDecoder Class / dart:utf Library / Dart API Reference

Utf16BytesToCodeUnitsDecoder Class

Convert UTF-16 encoded bytes to UTF-16 code units by grouping 1-2 bytes to produce the code unit (0-(2^16)-1). Relies on BOM to determine endian-ness, and defaults to BE.

Subclasses

Utf16beBytesToCodeUnitsDecoder, Utf16leBytesToCodeUnitsDecoder

Constructors

Code factory Utf16BytesToCodeUnitsDecoder(List<int> utf16EncodedBytes, [int offset = 0, int length, int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) #

factory Utf16BytesToCodeUnitsDecoder(List<int> utf16EncodedBytes, [
    int offset = 0, int length,
    int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) {
  if (length == null) {
    length = utf16EncodedBytes.length - offset;
  }
  if (hasUtf16beBom(utf16EncodedBytes, offset, length)) {
    return new Utf16beBytesToCodeUnitsDecoder(utf16EncodedBytes, offset + 2,
        length - 2, false, replacementCodepoint);
  } else if (hasUtf16leBom(utf16EncodedBytes, offset, length)) {
    return new Utf16leBytesToCodeUnitsDecoder(utf16EncodedBytes, offset + 2,
        length - 2, false, replacementCodepoint);
  } else {
    return new Utf16beBytesToCodeUnitsDecoder(utf16EncodedBytes, offset,
        length, false, replacementCodepoint);
  }
}

Code new Utf16BytesToCodeUnitsDecoder._fromListRangeIterator(_ListRangeIterator utf16EncodedBytesIterator, int replacementCodepoint) #

Utf16BytesToCodeUnitsDecoder._fromListRangeIterator(
    _ListRangeIterator this.utf16EncodedBytesIterator,
    int this.replacementCodepoint);

Methods

Code void backup([int by = 1]) #

void backup([int by = 1]) {
  utf16EncodedBytesIterator.backup(2 * by);
}

Code int decode() #

abstract int decode();

Code List<int> decodeRest() #

Provides a fast way to decode the rest of the source bytes in a single call. This method trades memory for improved speed in that it potentially over-allocates the List containing results.

List<int> decodeRest() {
  List<int> codeunits = new List<int>(remaining);
  int i = 0;
  while (hasNext()) {
    codeunits[i++] = next();
  }
  if (i == codeunits.length) {
    return codeunits;
  } else {
    List<int> truncCodeunits = new List<int>(i);
    truncCodeunits.setRange(0, i, codeunits);
    return truncCodeunits;
  }
}

Code bool hasNext() #

bool hasNext() => utf16EncodedBytesIterator.hasNext();

Code int next() #

int next() {
  if (utf16EncodedBytesIterator.remaining < 2) {
    utf16EncodedBytesIterator.next();
    if (replacementCodepoint != null) {
      return replacementCodepoint;
    } else {
      throw new IllegalArgumentException(
          "Invalid UTF16 at ${utf16EncodedBytesIterator.position}");
    }
  } else {
    return decode();
  }
}

Code int get position() #

int get position() => utf16EncodedBytesIterator.position ~/ 2;

Code int get remaining() #

int get remaining() => (utf16EncodedBytesIterator.remaining + 1) ~/ 2;

Code void skip([int count = 1]) #

void skip([int count = 1]) {
  utf16EncodedBytesIterator.skip(2 * count);
}

Fields

Code final int replacementCodepoint #

final int replacementCodepoint;

Code final _ListRangeIterator utf16EncodedBytesIterator #

final _ListRangeIterator utf16EncodedBytesIterator;

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