| // 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-32 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 replacementCharacter to null to throw an ArgumentError |
| * rather than replace the bad value. |
| */ |
| IterableUtf32Decoder decodeUtf32AsIterable(List<int> bytes, [ |
| int offset = 0, int length, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| return new IterableUtf32Decoder._( |
| () => new Utf32BytesDecoder(bytes, offset, length, replacementCodepoint)); |
| } |
| |
| /** |
| * Decodes the UTF-32BE 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 replacementCharacter to null to throw an ArgumentError |
| * rather than replace the bad value. |
| */ |
| IterableUtf32Decoder decodeUtf32beAsIterable(List<int> bytes, [ |
| int offset = 0, int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| return new IterableUtf32Decoder._( |
| () => new Utf32beBytesDecoder(bytes, offset, length, stripBom, |
| replacementCodepoint)); |
| } |
| |
| /** |
| * Decodes the UTF-32LE 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 replacementCharacter to null to throw an ArgumentError |
| * rather than replace the bad value. |
| */ |
| IterableUtf32Decoder decodeUtf32leAsIterable(List<int> bytes, [ |
| int offset = 0, int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| return new IterableUtf32Decoder._( |
| () => new Utf32leBytesDecoder(bytes, offset, length, stripBom, |
| replacementCodepoint)); |
| } |
| |
| /** |
| * Produce a String from a sequence of UTF-32 encoded bytes. The parameters |
| * allow an offset into a list of bytes (as int), limiting the length of the |
| * values be decoded and the ability of override the default Unicode |
| * replacement character. Set the replacementCharacter to null to throw an |
| * ArgumentError rather than replace the bad value. |
| */ |
| String decodeUtf32(List<int> bytes, [int offset = 0, int length, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| return new String.fromCharCodes((new Utf32BytesDecoder(bytes, offset, length, |
| replacementCodepoint)).decodeRest()); |
| } |
| /** |
| * Produce a String from a sequence of UTF-32BE encoded bytes. The parameters |
| * allow an offset into a list of bytes (as int), limiting the length of the |
| * values be decoded and the ability of override the default Unicode |
| * replacement character. Set the replacementCharacter to null to throw an |
| * ArgumentError rather than replace the bad value. |
| */ |
| String decodeUtf32be( |
| List<int> bytes, [int offset = 0, int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) => |
| new String.fromCharCodes((new Utf32beBytesDecoder(bytes, offset, length, |
| stripBom, replacementCodepoint)).decodeRest()); |
| |
| /** |
| * Produce a String from a sequence of UTF-32LE encoded bytes. The parameters |
| * allow an offset into a list of bytes (as int), limiting the length of the |
| * values be decoded and the ability of override the default Unicode |
| * replacement character. Set the replacementCharacter to null to throw an |
| * ArgumentError rather than replace the bad value. |
| */ |
| String decodeUtf32le( |
| List<int> bytes, [int offset = 0, int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) => |
| new String.fromCharCodes((new Utf32leBytesDecoder(bytes, offset, length, |
| stripBom, replacementCodepoint)).decodeRest()); |
| |
| /** |
| * Produce a list of UTF-32 encoded bytes. This method prefixes the resulting |
| * bytes with a big-endian byte-order-marker. |
| */ |
| List<int> encodeUtf32(String str) => |
| encodeUtf32be(str, true); |
| |
| /** |
| * Produce a list of UTF-32BE encoded bytes. By default, this method produces |
| * UTF-32BE bytes with no BOM. |
| */ |
| List<int> encodeUtf32be(String str, [bool writeBOM = false]) { |
| List<int> utf32CodeUnits = stringToCodepoints(str); |
| List<int> encoding = new List<int>(4 * utf32CodeUnits.length + |
| (writeBOM ? 4 : 0)); |
| int i = 0; |
| if (writeBOM) { |
| encoding[i++] = 0; |
| encoding[i++] = 0; |
| encoding[i++] = UNICODE_UTF_BOM_HI; |
| encoding[i++] = UNICODE_UTF_BOM_LO; |
| } |
| for (int unit in utf32CodeUnits) { |
| encoding[i++] = (unit >> 24) & UNICODE_BYTE_ZERO_MASK; |
| encoding[i++] = (unit >> 16) & UNICODE_BYTE_ZERO_MASK; |
| encoding[i++] = (unit >> 8) & UNICODE_BYTE_ZERO_MASK; |
| encoding[i++] = unit & UNICODE_BYTE_ZERO_MASK; |
| } |
| return encoding; |
| } |
| |
| /** |
| * Produce a list of UTF-32LE encoded bytes. By default, this method produces |
| * UTF-32BE bytes with no BOM. |
| */ |
| List<int> encodeUtf32le(String str, [bool writeBOM = false]) { |
| List<int> utf32CodeUnits = stringToCodepoints(str); |
| List<int> encoding = new List<int>(4 * utf32CodeUnits.length + |
| (writeBOM ? 4 : 0)); |
| int i = 0; |
| if (writeBOM) { |
| encoding[i++] = UNICODE_UTF_BOM_LO; |
| encoding[i++] = UNICODE_UTF_BOM_HI; |
| encoding[i++] = 0; |
| encoding[i++] = 0; |
| } |
| for (int unit in utf32CodeUnits) { |
| encoding[i++] = unit & UNICODE_BYTE_ZERO_MASK; |
| encoding[i++] = (unit >> 8) & UNICODE_BYTE_ZERO_MASK; |
| encoding[i++] = (unit >> 16) & UNICODE_BYTE_ZERO_MASK; |
| encoding[i++] = (unit >> 24) & UNICODE_BYTE_ZERO_MASK; |
| } |
| return encoding; |
| } |
| |
| /** |
| * Identifies whether a List of bytes starts (based on offset) with a |
| * byte-order marker (BOM). |
| */ |
| bool hasUtf32Bom( |
| List<int> utf32EncodedBytes, [int offset = 0, int length]) { |
| return hasUtf32beBom(utf32EncodedBytes, offset, length) || |
| hasUtf32leBom(utf32EncodedBytes, offset, length); |
| } |
| |
| /** |
| * Identifies whether a List of bytes starts (based on offset) with a |
| * big-endian byte-order marker (BOM). |
| */ |
| bool hasUtf32beBom(List<int> utf32EncodedBytes, [int offset = 0, int length]) { |
| int end = length != null ? offset + length : utf32EncodedBytes.length; |
| return (offset + 4) <= end && |
| utf32EncodedBytes[offset] == 0 && utf32EncodedBytes[offset + 1] == 0 && |
| utf32EncodedBytes[offset + 2] == UNICODE_UTF_BOM_HI && |
| utf32EncodedBytes[offset + 3] == UNICODE_UTF_BOM_LO; |
| } |
| |
| /** |
| * Identifies whether a List of bytes starts (based on offset) with a |
| * little-endian byte-order marker (BOM). |
| */ |
| bool hasUtf32leBom(List<int> utf32EncodedBytes, [int offset = 0, int length]) { |
| int end = length != null ? offset + length : utf32EncodedBytes.length; |
| return (offset + 4) <= end && |
| utf32EncodedBytes[offset] == UNICODE_UTF_BOM_LO && |
| utf32EncodedBytes[offset + 1] == UNICODE_UTF_BOM_HI && |
| utf32EncodedBytes[offset + 2] == 0 && utf32EncodedBytes[offset + 3] == 0; |
| } |
| |
| typedef Utf32BytesDecoder Utf32BytesDecoderProvider(); |
| |
| /** |
| * Return type of [decodeUtf32AsIterable] 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 IterableUtf32Decoder extends IterableBase<int> { |
| final Utf32BytesDecoderProvider codeunitsProvider; |
| |
| IterableUtf32Decoder._(this.codeunitsProvider); |
| |
| Utf32BytesDecoder get iterator => codeunitsProvider(); |
| } |
| |
| /** |
| * Abstrace parent class converts encoded bytes to codepoints. |
| */ |
| abstract class Utf32BytesDecoder implements _ListRangeIterator { |
| final _ListRangeIterator utf32EncodedBytesIterator; |
| final int replacementCodepoint; |
| int _current = null; |
| |
| Utf32BytesDecoder._fromListRangeIterator( |
| this.utf32EncodedBytesIterator, this.replacementCodepoint); |
| |
| factory Utf32BytesDecoder(List<int> utf32EncodedBytes, [ |
| int offset = 0, int length, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) { |
| if (length == null) { |
| length = utf32EncodedBytes.length - offset; |
| } |
| if (hasUtf32beBom(utf32EncodedBytes, offset, length)) { |
| return new Utf32beBytesDecoder(utf32EncodedBytes, offset + 4, length - 4, |
| false, replacementCodepoint); |
| } else if (hasUtf32leBom(utf32EncodedBytes, offset, length)) { |
| return new Utf32leBytesDecoder(utf32EncodedBytes, offset + 4, length - 4, |
| false, replacementCodepoint); |
| } else { |
| return new Utf32beBytesDecoder(utf32EncodedBytes, offset, length, false, |
| replacementCodepoint); |
| } |
| } |
| |
| List<int> decodeRest() { |
| List<int> codeunits = new List<int>(remaining); |
| int i = 0; |
| while (moveNext()) { |
| codeunits[i++] = current; |
| } |
| return codeunits; |
| } |
| |
| int get current => _current; |
| |
| bool moveNext() { |
| _current = null; |
| if (utf32EncodedBytesIterator.remaining < 4) { |
| utf32EncodedBytesIterator.skip(utf32EncodedBytesIterator.remaining); |
| if (replacementCodepoint != null) { |
| _current = replacementCodepoint; |
| return true; |
| } else { |
| throw new ArgumentError( |
| "Invalid UTF32 at ${utf32EncodedBytesIterator.position}"); |
| } |
| } else { |
| int codepoint = decode(); |
| if (_validCodepoint(codepoint)) { |
| _current = codepoint; |
| return true; |
| } else if (replacementCodepoint != null) { |
| _current = replacementCodepoint; |
| return true; |
| } else { |
| throw new ArgumentError( |
| "Invalid UTF32 at ${utf32EncodedBytesIterator.position}"); |
| } |
| } |
| } |
| |
| int get position => utf32EncodedBytesIterator.position ~/ 4; |
| |
| void backup([int by = 1]) { |
| utf32EncodedBytesIterator.backup(4 * by); |
| } |
| |
| int get remaining => (utf32EncodedBytesIterator.remaining + 3) ~/ 4; |
| |
| void skip([int count = 1]) { |
| utf32EncodedBytesIterator.skip(4 * count); |
| } |
| |
| int decode(); |
| } |
| |
| /** |
| * Convert UTF-32BE encoded bytes to codepoints by grouping 4 bytes |
| * to produce the unicode codepoint. |
| */ |
| class Utf32beBytesDecoder extends Utf32BytesDecoder { |
| Utf32beBytesDecoder(List<int> utf32EncodedBytes, [int offset = 0, |
| int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) : |
| super._fromListRangeIterator( |
| (new _ListRange(utf32EncodedBytes, offset, length)).iterator, |
| replacementCodepoint) { |
| if (stripBom && hasUtf32beBom(utf32EncodedBytes, offset, length)) { |
| skip(); |
| } |
| } |
| |
| int decode() { |
| utf32EncodedBytesIterator.moveNext(); |
| int value = utf32EncodedBytesIterator.current; |
| utf32EncodedBytesIterator.moveNext(); |
| value = (value << 8) + utf32EncodedBytesIterator.current; |
| utf32EncodedBytesIterator.moveNext(); |
| value = (value << 8) + utf32EncodedBytesIterator.current; |
| utf32EncodedBytesIterator.moveNext(); |
| value = (value << 8) + utf32EncodedBytesIterator.current; |
| return value; |
| } |
| } |
| |
| /** |
| * Convert UTF-32BE encoded bytes to codepoints by grouping 4 bytes |
| * to produce the unicode codepoint. |
| */ |
| class Utf32leBytesDecoder extends Utf32BytesDecoder { |
| Utf32leBytesDecoder(List<int> utf32EncodedBytes, [int offset = 0, |
| int length, bool stripBom = true, |
| int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) : |
| super._fromListRangeIterator( |
| (new _ListRange(utf32EncodedBytes, offset, length)).iterator, |
| replacementCodepoint) { |
| if (stripBom && hasUtf32leBom(utf32EncodedBytes, offset, length)) { |
| skip(); |
| } |
| } |
| |
| int decode() { |
| utf32EncodedBytesIterator.moveNext(); |
| int value = utf32EncodedBytesIterator.current; |
| utf32EncodedBytesIterator.moveNext(); |
| value += (utf32EncodedBytesIterator.current << 8); |
| utf32EncodedBytesIterator.moveNext(); |
| value += (utf32EncodedBytesIterator.current << 16); |
| utf32EncodedBytesIterator.moveNext(); |
| value += (utf32EncodedBytesIterator.current << 24); |
| return value; |
| } |
| } |
| |
| bool _validCodepoint(int codepoint) { |
| return (codepoint >= 0 && codepoint < UNICODE_UTF16_RESERVED_LO) || |
| (codepoint > UNICODE_UTF16_RESERVED_HI && |
| codepoint < UNICODE_VALID_RANGE_MAX); |
| } |