| // Copyright (c) 2012, 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. |
| |
| part of dart.utf; |
| |
| /** |
| * Decodes the UTF-16 bytes as an iterable. Thus, the consumer can only convert |
| * as much of the input as needed. Determines the byte order from the BOM, |
| * or uses big-endian as a default. This method always strips a leading BOM. |
| * Set the [replacementCodepoint] to null to throw an ArgumentError |
| * rather than replace the bad value. The default value for |
| * [replacementCodepoint] is U+FFFD. |
| */ |
| IterableUtf16Decoder decodeUtf16AsIterable(List<int> bytes, [int offset = 0, |
| int length, int replacementCodepoint = |
| UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| return new IterableUtf16Decoder._( |
| () => new Utf16BytesToCodeUnitsDecoder(bytes, offset, length, |
| replacementCodepoint), replacementCodepoint); |
| } |
| |
| /** |
| * Decodes the UTF-16BE bytes as an iterable. Thus, the consumer can only |
| * convert as much of the input as needed. This method strips a leading BOM by |
| * default, but can be overridden by setting the optional parameter [stripBom] |
| * to false. Set the [replacementCodepoint] to null to throw an |
| * ArgumentError rather than replace the bad value. The default |
| * value for the [replacementCodepoint] is U+FFFD. |
| */ |
| IterableUtf16Decoder decodeUtf16beAsIterable(List<int> bytes, [int offset = 0, |
| int length, bool stripBom = true, int replacementCodepoint = |
| UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| return new IterableUtf16Decoder._( |
| () => new Utf16beBytesToCodeUnitsDecoder(bytes, offset, length, stripBom, |
| replacementCodepoint), replacementCodepoint); |
| } |
| |
| /** |
| * Decodes the UTF-16LE bytes as an iterable. Thus, the consumer can only |
| * convert as much of the input as needed. This method strips a leading BOM by |
| * default, but can be overridden by setting the optional parameter [stripBom] |
| * to false. Set the [replacementCodepoint] to null to throw an |
| * ArgumentError rather than replace the bad value. The default |
| * value for the [replacementCodepoint] is U+FFFD. |
| */ |
| IterableUtf16Decoder decodeUtf16leAsIterable(List<int> bytes, [int offset = 0, |
| int length, bool stripBom = true, int replacementCodepoint = |
| UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| return new IterableUtf16Decoder._( |
| () => new Utf16leBytesToCodeUnitsDecoder(bytes, offset, length, stripBom, |
| replacementCodepoint), replacementCodepoint); |
| } |
| |
| /** |
| * Produce a String from a sequence of UTF-16 encoded bytes. This method always |
| * strips a leading BOM. Set the [replacementCodepoint] to null to throw an |
| * ArgumentError rather than replace the bad value. The default |
| * value for the [replacementCodepoint] is U+FFFD. |
| */ |
| String decodeUtf16(List<int> bytes, [int offset = 0, int length, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| Utf16BytesToCodeUnitsDecoder decoder = new Utf16BytesToCodeUnitsDecoder(bytes, |
| offset, length, replacementCodepoint); |
| List<int> codeunits = decoder.decodeRest(); |
| return new String.fromCharCodes( |
| _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint)); |
| } |
| |
| /** |
| * Produce a String from a sequence of UTF-16BE encoded bytes. This method |
| * strips a leading BOM by default, but can be overridden by setting the |
| * optional parameter [stripBom] to false. Set the [replacementCodepoint] to |
| * null to throw an ArgumentError rather than replace the bad value. |
| * The default value for the [replacementCodepoint] is U+FFFD. |
| */ |
| String decodeUtf16be(List<int> bytes, [int offset = 0, int length, |
| bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| List<int> codeunits = (new Utf16beBytesToCodeUnitsDecoder(bytes, offset, |
| length, stripBom, replacementCodepoint)).decodeRest(); |
| return new String.fromCharCodes( |
| _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint)); |
| } |
| |
| /** |
| * Produce a String from a sequence of UTF-16LE encoded bytes. This method |
| * strips a leading BOM by default, but can be overridden by setting the |
| * optional parameter [stripBom] to false. Set the [replacementCodepoint] to |
| * null to throw an ArgumentError rather than replace the bad value. |
| * The default value for the [replacementCodepoint] is U+FFFD. |
| */ |
| String decodeUtf16le(List<int> bytes, [int offset = 0, int length, |
| bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| List<int> codeunits = (new Utf16leBytesToCodeUnitsDecoder(bytes, offset, |
| length, stripBom, replacementCodepoint)).decodeRest(); |
| return new String.fromCharCodes( |
| _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint)); |
| } |
| |
| /** |
| * Produce a list of UTF-16 encoded bytes. This method prefixes the resulting |
| * bytes with a big-endian byte-order-marker. |
| */ |
| List<int> encodeUtf16(String str) => |
| encodeUtf16be(str, true); |
| |
| /** |
| * Produce a list of UTF-16BE encoded bytes. By default, this method produces |
| * UTF-16BE bytes with no BOM. |
| */ |
| List<int> encodeUtf16be(String str, [bool writeBOM = false]) { |
| List<int> utf16CodeUnits = _stringToUtf16CodeUnits(str); |
| List<int> encoding = |
| new List<int>.fixedLength(2 * utf16CodeUnits.length + (writeBOM ? 2 : 0)); |
| int i = 0; |
| if (writeBOM) { |
| encoding[i++] = UNICODE_UTF_BOM_HI; |
| encoding[i++] = UNICODE_UTF_BOM_LO; |
| } |
| for (int unit in utf16CodeUnits) { |
| encoding[i++] = (unit & UNICODE_BYTE_ONE_MASK) >> 8; |
| encoding[i++] = unit & UNICODE_BYTE_ZERO_MASK; |
| } |
| return encoding; |
| } |
| |
| /** |
| * Produce a list of UTF-16LE encoded bytes. By default, this method produces |
| * UTF-16LE bytes with no BOM. |
| */ |
| List<int> encodeUtf16le(String str, [bool writeBOM = false]) { |
| List<int> utf16CodeUnits = _stringToUtf16CodeUnits(str); |
| List<int> encoding = |
| new List<int>.fixedLength(2 * utf16CodeUnits.length + (writeBOM ? 2 : 0)); |
| int i = 0; |
| if (writeBOM) { |
| encoding[i++] = UNICODE_UTF_BOM_LO; |
| encoding[i++] = UNICODE_UTF_BOM_HI; |
| } |
| for (int unit in utf16CodeUnits) { |
| encoding[i++] = unit & UNICODE_BYTE_ZERO_MASK; |
| encoding[i++] = (unit & UNICODE_BYTE_ONE_MASK) >> 8; |
| } |
| return encoding; |
| } |
| |
| /** |
| * Identifies whether a List of bytes starts (based on offset) with a |
| * byte-order marker (BOM). |
| */ |
| bool hasUtf16Bom(List<int> utf32EncodedBytes, [int offset = 0, int length]) { |
| return hasUtf16beBom(utf32EncodedBytes, offset, length) || |
| hasUtf16leBom(utf32EncodedBytes, offset, length); |
| } |
| |
| /** |
| * Identifies whether a List of bytes starts (based on offset) with a |
| * big-endian byte-order marker (BOM). |
| */ |
| bool hasUtf16beBom(List<int> utf16EncodedBytes, [int offset = 0, int length]) { |
| int end = length != null ? offset + length : utf16EncodedBytes.length; |
| return (offset + 2) <= end && |
| utf16EncodedBytes[offset] == UNICODE_UTF_BOM_HI && |
| utf16EncodedBytes[offset + 1] == UNICODE_UTF_BOM_LO; |
| } |
| |
| /** |
| * Identifies whether a List of bytes starts (based on offset) with a |
| * little-endian byte-order marker (BOM). |
| */ |
| bool hasUtf16leBom(List<int> utf16EncodedBytes, [int offset = 0, int length]) { |
| int end = length != null ? offset + length : utf16EncodedBytes.length; |
| return (offset + 2) <= end && |
| utf16EncodedBytes[offset] == UNICODE_UTF_BOM_LO && |
| utf16EncodedBytes[offset + 1] == UNICODE_UTF_BOM_HI; |
| } |
| |
| List<int> _stringToUtf16CodeUnits(String str) { |
| return _codepointsToUtf16CodeUnits(str.charCodes); |
| } |
| |
| typedef _ListRangeIterator _CodeUnitsProvider(); |
| |
| /** |
| * Return type of [decodeUtf16AsIterable] and variants. The Iterable type |
| * provides an iterator on demand and the iterator will only translate bytes |
| * as requested by the user of the iterator. (Note: results are not cached.) |
| */ |
| // TODO(floitsch): Consider removing the extend and switch to implements since |
| // that's cheaper to allocate. |
| class IterableUtf16Decoder extends Iterable<int> { |
| final _CodeUnitsProvider codeunitsProvider; |
| final int replacementCodepoint; |
| |
| IterableUtf16Decoder._(this.codeunitsProvider, this.replacementCodepoint); |
| |
| Utf16CodeUnitDecoder get iterator => |
| new Utf16CodeUnitDecoder.fromListRangeIterator(codeunitsProvider(), |
| replacementCodepoint); |
| } |
| |
| /** |
| * 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. |
| */ |
| class Utf16BytesToCodeUnitsDecoder implements _ListRangeIterator { |
| final _ListRangeIterator utf16EncodedBytesIterator; |
| final int replacementCodepoint; |
| int _current = null; |
| |
| Utf16BytesToCodeUnitsDecoder._fromListRangeIterator( |
| this.utf16EncodedBytesIterator, this.replacementCodepoint); |
| |
| 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); |
| } |
| } |
| |
| /** |
| * 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>.fixedLength(remaining); |
| int i = 0; |
| while (moveNext()) { |
| codeunits[i++] = current; |
| } |
| if (i == codeunits.length) { |
| return codeunits; |
| } else { |
| List<int> truncCodeunits = new List<int>.fixedLength(i); |
| truncCodeunits.setRange(0, i, codeunits); |
| return truncCodeunits; |
| } |
| } |
| |
| int get current => _current; |
| |
| bool moveNext() { |
| _current = null; |
| if (utf16EncodedBytesIterator.remaining < 2) { |
| utf16EncodedBytesIterator.moveNext(); |
| if (replacementCodepoint != null) { |
| _current = replacementCodepoint; |
| return true; |
| } else { |
| throw new ArgumentError( |
| "Invalid UTF16 at ${utf16EncodedBytesIterator.position}"); |
| } |
| } else { |
| _current = decode(); |
| return true; |
| } |
| } |
| |
| int get position => utf16EncodedBytesIterator.position ~/ 2; |
| |
| void backup([int by = 1]) { |
| utf16EncodedBytesIterator.backup(2 * by); |
| } |
| |
| int get remaining => (utf16EncodedBytesIterator.remaining + 1) ~/ 2; |
| |
| void skip([int count = 1]) { |
| utf16EncodedBytesIterator.skip(2 * count); |
| } |
| |
| int decode(); |
| } |
| |
| /** |
| * Convert UTF-16BE encoded bytes to utf16 code units by grouping 1-2 bytes |
| * to produce the code unit (0-(2^16)-1). |
| */ |
| class Utf16beBytesToCodeUnitsDecoder extends Utf16BytesToCodeUnitsDecoder { |
| Utf16beBytesToCodeUnitsDecoder(List<int> utf16EncodedBytes, [ |
| int offset = 0, int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) : |
| super._fromListRangeIterator( |
| (new _ListRange(utf16EncodedBytes, offset, length)).iterator, |
| replacementCodepoint) { |
| if (stripBom && hasUtf16beBom(utf16EncodedBytes, offset, length)) { |
| skip(); |
| } |
| } |
| |
| int decode() { |
| utf16EncodedBytesIterator.moveNext(); |
| int hi = utf16EncodedBytesIterator.current; |
| utf16EncodedBytesIterator.moveNext(); |
| int lo = utf16EncodedBytesIterator.current; |
| return (hi << 8) + lo; |
| } |
| } |
| |
| /** |
| * Convert UTF-16LE encoded bytes to utf16 code units by grouping 1-2 bytes |
| * to produce the code unit (0-(2^16)-1). |
| */ |
| class Utf16leBytesToCodeUnitsDecoder extends Utf16BytesToCodeUnitsDecoder { |
| Utf16leBytesToCodeUnitsDecoder(List<int> utf16EncodedBytes, [ |
| int offset = 0, int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) : |
| super._fromListRangeIterator( |
| (new _ListRange(utf16EncodedBytes, offset, length)).iterator, |
| replacementCodepoint) { |
| if (stripBom && hasUtf16leBom(utf16EncodedBytes, offset, length)) { |
| skip(); |
| } |
| } |
| |
| int decode() { |
| utf16EncodedBytesIterator.moveNext(); |
| int lo = utf16EncodedBytesIterator.current; |
| utf16EncodedBytesIterator.moveNext(); |
| int hi = utf16EncodedBytesIterator.current; |
| return (hi << 8) + lo; |
| } |
| } |