Get XLocaleMatcher ready for replacing the LocaleMatcher code.
More simplifications beyond ICU-20330 PR #409, smaller data, some more optimizations.
New API ready to be moved over.
- less work for region partitions distance lookup:
- encode each array of single-character partition strings as one string
- look up each desired partition only once, not for each (desired, supported) pair
- look up the * fallback region distance only for the first mismatch, not for each non-matching pair
- skip region distance lookup if minRegionDistance>=remainingThreshold
- locale distance table: remove subtables that contain only *-* with default script/region distance
- mark intermediate subtag matches via last-character bit 7, not also with a match value
- likely subtags data: prune trailing *-only levels, and skip *-only script levels; likely subtags perf test
- likely subtags: skip_script=1; LSR.indexForRegion(ill-formed)=0 not negative
- likely subtags small optimization: array lookup for first letter of language subtag
- defaultDemotionPerDesiredLocale=distance(en, en-GB)
- favor=script: still reject a script mismatch
- if an explicit default locale is given, prefer that (by LSR), not the first supported locale
- XLocaleMatcher.Builder: copy supported locales into a List not a Set to preserve input indexes; duplicates are harmless
- match by LSR only, not exact locale match; results consistent with no fastpath, simpler, sometimes a little slower
- internal getBestMatch() returns just the suppIndex
- store the best desired locale & index in an LSR iterator
- make an LSR from Locale without ULocale detour
- adjust the XLocaleMatcher API as proposed; remove unused internal methods; clean up LocalePriorityList docs
- Changes Java DecimalFormat boolean get* methods to is*.
- Makes the new draft methods non-virtual.
- Removes obsolete template class in header file.
- Adds proper U_HIDE tags in unum.h and decimfmt.h
- Adds additional logic to NumberStringBuilder.
- Extends logic of number::impl::Field type.
- Adds tests for RBNF support.
- Adds tests from ftang's original PR.
- widen API from LocalePriorityList to Iterable
- merge getBestMatch(multiple locales) and getBestMatch(single locale) into one function
- process desired locales incrementally, create fewer objects
- reject poor matches early: use bestDistance-demotion for threshold
- add API for java.util.Locale, convert incrementally
- new feature: tracks indexes of supported and desired locales which eliminates conversion of result objects in wrappers around getBestMatch() as shown by the java.util.Locale API here
- simpler data structures, more serialization-friendly (easier to port to C++)
- e.g., use a BytesTrie each for likelySubtags & locale distance, instead of layers of TreeMap
- un-hardcode locale matcher data; use modern resource bundle functions
- split builder code & runtime code into separate classes
- move LSR to simple top-level value class, cache regionIndex in LSR
- simpler handling of private use languages and pseudolocales
- simplify RegionMapper
- LocaleDistance builder: move the node distance into the DistanceTable, remove DistanceNode
- support distance rules with region codes, not just with variables
- enforce & use distance rule constraints:
- no rule with *,supported or desired,*
- no rule with language * and script/region non-*
- distance trie collapse a (desired, supported)=(ANY, ANY) pair into a single *
- look up each desired language only once for all supported LSRs
- remove layers-of-Maps compaction (trie builder compacts)
- remove unused XML printing
- remove other unused code
- make XLocaleMatcherTest.testPerf() exercise locale distance lookup code
