The streaming decoder previously selected an encoding only from a byte-order
mark or the UTF sniff, so its single-byte and CJK decode paths were latent. It
now reads the encoding from the XML declaration (the libxml2 behavior) when
there is no BOM, activating those paths over an incremental byte source. Add
the streaming form of ISO-2022-JP, carrying the stateful mode across reads
(extracted to its own file to stay under the type-body cap). A test asserts
streaming agrees with whole-buffer decode for a single-byte (ISO-8859-1), a
CJK (Shift_JIS), and an ISO-2022-JP document.
Part of #108, #105
Add the WHATWG big5 decoder over the vendored index-big5 (18,590 entries),
for both the whole-buffer and streaming decoders. A lead in 0x81-0xFE plus
a trail in 0x40-0x7E or 0xA1-0xFE resolves through the index, covering
Traditional Chinese and the HKSCS extensions including the astral CJK
ideographs. Four pointers decode to a base letter plus a combining mark.
Selected by the big5 / big5-hkscs declaration names.
Closes#103
Extend the GBK two-byte subset to full GB18030: a lead byte followed by
a digit opens a four-byte form whose pointer is mapped through the WHATWG
index-gb18030-ranges linear ranges, reaching the supplementary planes.
The 207 ranges are vendored verbatim. Wired into the whole-buffer and
streaming decoders and the encoding-name table (gb18030/gb-18030).
Closes#102
Decode UTF-32 (both byte orders, BOM or sniffed) and the single-byte encodings
ISO-8859-1 and Windows-1252, selected by the XML declaration's encoding name,
in addition to UTF-8 and UTF-16. The streaming byte path also handles UTF-32.
Standard library only, no Foundation. Closes#28. Reimplemented from the
documented encoding algorithms; no upstream code copied. 4 tests; 94 total.
Add PureXML.parse(pullingBytes:) and events(pullingBytes:) over an incremental
byte source (() -> UInt8?). StreamingDecoder detects the encoding from the
leading bytes, strips any BOM, and yields one scalar at a time as a Character,
so a byte stream is never fully buffered. UTF-8 (1 to 4 bytes) and UTF-16 (with
surrogate pairs) are decoded incrementally; invalid sequences become the Unicode
replacement character. Standard library only, no Foundation. Reimplemented from
the documented UTF decoding rules; no upstream code copied.
