The localeCompare table now covers U+0363-U+036F, U+00BC-U+00BE and
U+2044 FRACTION SLASH, so strings containing them follow Node's collation
instead of code-point order. A combining Latin letter is its letter's
primary at the letter's secondary, with a tertiary weight between the
letter's case forms where Node places it, and the combining class it
shares with the diacritics it reorders with. A vulgar fraction is the
elements of its compatibility decomposition (1, U+2044, 4), each with the
tertiary weight Node places the fraction at among that position's forms,
so it orders after both 1⁄4 and ¹⁄4. The generator's check adds the
fractions' slash and superscript spellings and the combining letters
around each diacritic. SC6003 and the limitations page describe the new
coverage.
The generated lookup indexes one dense table for every code point below
U+0370, with the gaps between ranges marked uncovered, and checks the
ranges above it (now U+2044) after that, so a Latin lookup is one
comparison instead of up to four.
The generated localeCompare table now agrees with Node on spellings that
tie at the primary and secondary levels. "l·" and "L·" collate as one
unit, equal to U+0140 and U+013F, through a contraction table. Precomposed
characters take their decompositions' elements after the case weights are
assigned, so U+0130 equals I + U+0307. Ligatures whose spelled-out letters
tie with them (ij and ij) get the case weight Node places them at among
their first letter's case forms, and ligatures with their own secondary
(Æ) keep their own case. The generator's check now also compares every
covered character's decompositions, case forms and ligature spellings in
four contexts. A per-thread class table lets the lazy primary comparison
find characters that need element lists with one lookup.
Chris Tate