icu4r_19 (1.0)

Nikolai Lugovoi, Perry Smith
2011-10-16T14:34:47Z

Ruby extension for Unicode support using ICU - 1.9.2 compatible

== ICU4R - ICU Unicode bindings for Ruby ICU4R is an attempt to provide better Unicode support for Ruby, where it lacks for a long time. Current code is mostly rewritten string.c from Ruby 1.8.3. ICU4R is Ruby C-extension binding for ICU library[1] and provides following classes and functionality: * UString: - String-like class with internal UTF16 storage; - UCA rules for UString comparisons (<=>, casecmp); - encoding(codepage) conversion; \ - Unicode normalization; - transliteration, also rule-based; Bunch of locale-sensitive functions: - upcase/downcase; - string collation; \ - string search; - iterators over text line/word/char/sentence breaks; \ - message formatting (number/currency/string/time); - date and number parsing. * URegexp - unicode regular expressions. * UResourceBundle - access to resource bundles, including ICU locale data. * UCalendar - date manipulation and timezone info. * UConverter - codepage conversions API * UCollator - locale-sensitive string comparison == Install and usage > ruby extconf.rb > make && make check > make install Now, in your scripts just require 'icu4r'. To create RDoc, run > sh tools/doc.sh == Requirements To build and use ICU4R you will need GCC and ICU v3.4 libraries[2]. == Differences from Ruby String and Regexp classes === UString vs String 1. UString substring/index methods use UTF16 codeunit indexes, not code points. 2. UString supports most methods from String class. Missing methods are: capitalize, capitalize!, swapcase, swapcase! %, center, ljust, rjust chomp, chomp!, chop, chop! \ count, delete, delete!, squeeze, squeeze!, tr, tr!, tr_s, tr_s! crypt, intern, sum, unpack dump, each_byte, each_line hex, oct, to_i, to_sym reverse, reverse! succ, succ!, next, next!, upto 3. Instead of String#% method, UString#format is provided. See FORMATTING for short reference. 4. UStrings can be created via String.to_u(encoding='utf8') or global u(str,[encoding='utf8']) calls. Note that +encoding+ parameter must be value of String class. 5. There's difference between character grapheme, codepoint and codeunit. See UNICODE reports for gory details, but in short: locale dependent notion of character can be presented using more than one codepoint - base letter and combining (accents) (also possible more than one!), and each codepoint can require more than one codeunit to store (for UTF8 codeunit size is 8bit, though \ some codepoints require up to 4bytes). So, UString has normalization and locale dependent break iterators. 6. Currently UString doesn't include Enumerable module. 7. UString index/[] methods which accept URegexp, throw exception if Regexp passed. 8. UString#<=>, UString#casecmp use UCA rules. === URegexp UString uses ICU regexp library. Pattern syntax is described in [./docs/UNICODE_REGEXPS] and ICU docs. There are some differences between processing in Ruby Regexp and URegexp: 1. When UString#sub, UString#gsub are called with block, special vars ($~, $&, $1, ...) aren't set, as their values are processed through deep ruby core code. Instead, block receives UMatch object, which is essentially immutable array of matching groups: "test".u.gsub(ure("(e)(.)")) do |match| \ puts match[0] # => 'es' <--> $& puts match[1] # => 'e' \ <--> $1 puts match[2] # => 's' <--> $2 end 2. In URegexp search pattern backreferences are in form \n (\1, \2, ...), in replacement string - in form $1, $2, ... NOTE: URegexp considers char to be a digit NOT ONLY ASCII (0x0030-0x0039), but any Unicode char, which has property Decimal digit number (Nd), e.g.: a = [?$, 0x1D7D9].pack("U*").u * 2 puts a.inspect_names DOLLAR SIGN MATHEMATICAL DOUBLE-STRUCK DIGIT ONE DOLLAR SIGN MATHEMATICAL DOUBLE-STRUCK DIGIT ONE puts "abracadabra".u.gsub(/(b)/.U, a) abbracadabbra \ 3. One can create URegexp using global Kernel#ure function, Regexp#U, Regexp#to_u, or from UString using URegexp.new, e.g: /pattern/.U =~ "string".u 4. There are differences about Regexp and URegexp multiline matching options: t = "text\ntest" # ^,$ handling : URegexp multiline <-> Ruby default t.u =~ ure('^\w+$', URegexp::MULTILINE) => # t =~ /^\w+$/ => 0 # . matches \n : URegexp DOTALL <-> /m t.u =~ ure('.+test', URegexp::DOTALL) \ => #