Embedded Files
Motivations
The RBBI rules as of ICU 4.6 are unable to express the UAX-14 line breaking behavior of Unicode 6.0. Some extensions are needed. The problem is with the reverse direction rule for UAX rule LB8.
A number of other rules could be expressed more easily if there were more fine grained control over rule chaining. It is currently either on or off for a complete set of rules.
Some of the existing rule syntax is extremely error prone.
Plain old bugs.
ICU Tickets
2783, #comments in rules fail with multi-line sets. May not make sense, in which case return the bug.
3058, Empty unicode set should not be an error. It turns out that there are uses for this. The contents of the set may come from a $Variable defined elsewhere, and, depending on options or whatever, a set may be empty.
#3640, \p{unicode property} syntax is not recognized in rules, only in sets.
#3769, make rule chaining optional per rule set. (This will be subsumed by #4441)
#4441, Rule Chaining Enhancements
Replache !!LBCMNoChain with something more general.
!!LookAheadHardBreak, remove this as an option, make it default. (Look-ahead breaks without this option are never used, behavior is not well defined and completely untested. They exist in a half-way attempt to maintain compatibility with the original Rich Gilliam engine.
#????, Look-ahead breaks, allow more than one to be in-flight at once. Needed for the UAX14 fixes. Requires changes to engine and to state tables. Probably a vector of length = number of states, vec[state] = input position when at a state corresponding to a '/', and side table for accepting states that complete a look-ahead, indicating which vector position(s) (states) have the break position.
#4444, Bugs with look-ahead breaks. Already fixed? Invesitigate.
#5451, 64 bit text indexes. UText does them.
Many More.
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