Sinhala does not have half forms. And most (all?) consonants can be
base, except when preceded by ZWJ, which would request a subjoined form.
Hence switch the base algorithm to categorize with Khmer, start search
at start, and stop at a ZWJ.
Also, mark all pos=base consonants after base to be subjoined. Mark
base itself to have pos=base.
Finally, adjust Sinhala's reph position to after-main.
Brings down Sinhala failures from 455 to 328 (0.120656%).
If, say, a H,ZWJ,C ligature was formed, we don't want the code to detec
that as a Halant. So, ignore ligatures when matching category in
final_reordering.
Sinhala failures down from 514 to 455 (0.167374%).
Seems to be about what Uniscribe does. Not exactly. But close enough.
More consonants will start a new cluster.
A few scripts went way down in failures. In particular:
- Devanagari failures went down from 490 to 56.
- Telugu went down from 113 to 49.
Other scripts went down slightly or didn't change. New numbers:
BENGALI: 353908 out of 354285 tests passed. 377 failed (0.106412%)
DEVANAGARI: 693572 out of 693628 tests passed. 56 failed (0.00807349%)
GUJARATI: 366485 out of 366506 tests passed. 21 failed (0.00572978%)
GURMUKHI: 60750 out of 60809 tests passed. 59 failed (0.0970251%)
KANNADA: 950730 out of 951913 tests passed. 1183 failed (0.124276%)
KHMER: 298613 out of 299124 tests passed. 511 failed (0.170832%)
MALAYALAM: 1046881 out of 1048416 tests passed. 1535 failed (0.146411%)
ORIYA: 42320 out of 42329 tests passed. 9 failed (0.021262%)
SINHALA: 271333 out of 271847 tests passed. 514 failed (0.189077%)
TAMIL: 1091837 out of 1091837 tests passed. 0 failed (0%)
TELUGU: 970524 out of 970573 tests passed. 49 failed (0.00504856%)
Some of the remaining Telugu and Devanagari issues seem to be Uniscribe
eating Anusvara when placed before a non-joiner. Ouch!
Uniscribe reorders U+0E3A to be after U+0E38 and U+0E39. We do that by
modifying the ccc for U+0E3A.
Fixes the two remaining Thai failures (see previous commit).
Adjust the list of marks before SARA AM that get the reordering
treatment. Also adjust cluster formation to match Uniscribe.
With Wikipedia test data, now I see:
- For Thai, with the Angsana New font from Win7, I see 54 failures out
of over 4M tests (0.00129107%). Of the 54, two are legitimate
reordering issues (fix coming soon), and the other 52 are simply
Uniscribe using a zero-width space char instead of an unknown
character for missing glyphs. No idea why. The missing-glyph
sequences include one that is a Thai character followed by an Arabic
Sokun. Someone confused it with Nikhahit I assume!
- For Lao, with the Dokchampa font from Win7, 33 tests fail out of
54k (0.0615167%). All seem to be insignificant mark positioning
with two marks on a base. Have to investigate.
Althought IndicMatraCategory.txt classifies it as Top_And_Right matra,
it does not have Unicode decomposition, and Uniscribe does not do
anything special about it either.
Gujarati failures down from 0.672% to 0.0130966%.
That's really what Uniscribe does, and explains a lot of pecularities of
Halant,ZWNJ before the base.
Sent Telugu from 1% failures to 0.03%. Improved Kannada and Malayalam
slightly. Fixed half of Bengali, and did NOT break anything!
Behdad Esfahbod