[HarfBuzz] question about indic matra group rule

Behdad Esfahbod behdad at behdad.org
Wed Jun 26 12:04:26 PDT 2013

On 13-06-17 12:06 AM, datao zhang wrote:
> Dear behdad:
> I feel confuse for the syllable rule in  hb-ot-shape-complex-indic-machine.rl:
> halant_or_matra_group = (final_halant_group | (h.ZWJ)? matra_group{0,4});
> I can't image there any case for indic script which 4 matra followed. I can
> understand you decompose some matra before syllable analysis, ex: Sinhala
> (0xDDC, after decompose, two matra generated). So you specify more than one
> matra. But I don't know why it is 4, not 2.

The 4 is what Uniscribe enforces, and we match right now.  But there was a
thread about two months back where we discussed lifting the limit completely.
 Will eventually do that.

> Another issue is caused that you decompose matra before syllable analysis and
> allow more than one matra followed. ex: if we have two matras: (0xDD9,0xDD9).
> They will be treated as one syllable. I don't know what benefit we can get
> from such rule. At least it obeys those MS Specific for Indic script.

Check the thread titled “Corner case wrt to repeating Malayalam vowel sign OO”
from February.


> Any comments is appreciated?
> Thanks!
> Br,
> Dean


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