Based on a PR pkg/20825 by Hiramatsu Yoshifumi, modified by me.
- follow PKG_SYSCONFDIR
List of major changes for this release:
* Regular Expressions Phase 1
ICU 2.4 introduces a Regular Expression C++ API that is modeled after
the JDK 1.4 API. ICU 2.4's Regular Expression API supports Unicode
level 1 regular expressions (see Unicode Regular Expression
Guidelines) but not all pattern metacharacters and features are
supported yet. Regular expressions leverage all of the UnicodeSet
support, including all Unicode 3.2 property names and property value
names. Future ICU releases will complete the pattern support, add
support for higher Unicode regex levels, and improve performance. For
more details see the API References and the User Guide.
* Modularized ICU library building
ICU 2.4 provides build-time switches to prune parts of the library
code, for smaller custom distributions. For details see the readme
file.
* Character set alias management support
Additional APIs map alias+standard to a unique charset name (e.g.,
"Shift-JIS"+"IANA"->"ibm-943_P14A-2000") and enumerate all charset
names in the alias table, not just the installed ones. See
convrtrs.txt and ucnv.h.
These APIs allow programmers to avoid data corruption problems when
different platforms use the same names for different character
conversion mappings.
* EBCDIC-z/OS converter option
The EBCDIC converter now handles swapped LF/NL mappings
algorithmically instead of with modified .ucm/.cnv conversion table
files. This makes this behavior available for all supported EBCDIC
conversions without adding to the data package size. See "swaplfnl" in
convrtrs.txt.
* Additional converter
A new converter implementation has been added for the encoding of IMAP
mailbox names. See RFC 2060/5.1.3. Mailbox International Naming
Convention and "IMAP-mailbox-name" in convrtrs.txt.
* Customizable break iteration
ICU 2.4 allows registration of a BreakIterator with a locale ID. This
allows applications to provide more sophisticated word/sentence break
engines and use them seamlessly with the ICU APIs. In future releases,
this registration mechanism will be extended to all relevant ICU
services. If you are interested in ICU customization, please try out
this feature.
* Collation performance
ICU 2.4 collation was improved in several areas, with an emphasis on
performance:
* Latin-1: Improved performance of u_strcoll().
* Russian/Cyrillic: Improved performance by tailoring collation for
cyrillic-script languages, removing UCA contractions that are not
used for modern Russian (this uses the [suppressContractions]
tailoring option).
* Korean: Improved performance by resolving collation elements for
modern Hangul syllables at build time (this uses the [optimize]
tailoring option).
* Japanese: The default strength for Japanese was reduced from
quaternary to tertiary as in all other locales.
* UnicodeSet performance
UnicodeSet performance is significantly improved, especially for
add(codePoint) and contains(codePoint).
* Unicode property aliases ICU 2.4 introduces APIs for mapping between
all appropriate Unicode property aliases and property value aliases
and ICU property enumeration constants. See u_getPropertyName() etc.
in uchar.h.
* Unicode string functions
* There are new C functions for searching for last occurrences of
characters and partial strings. See u_strrstr(), u_strrchr32()
etc.
* New C/C++/Java functions for efficient checking if a string
contains more than a certain number of code points. See
hasMoreChar32Than().
* Copying UnicodeStrings via the standard assignment operator and
copy constructor does not preserve readonly aliasing any more
because this can sometimes have unexpected and dangerous effects.
A new fastCopyFrom() member function provides the old copy
semantics. See Jitterbug 1794 for more details.
* UTF macros simplified
The low-level C macros for handling code points in 8-bit and 16-bit
Unicode strings have been replaced by a simpler, more consistent set
with more concise names. For details see utf_old.h and utf.h.
Similarly, ICU 2.4 defines the UChar32 consistently (now always as
int32_t) and adds a U_SENTINEL non-code point value for new APIs.
* Performance tests
ICU 2.4 has a new performance test framework and additional
performance tests using this framework. This is not currently
documented, but it is available as part of the source distribution at
source/test/perf/.
