README.chromium

Name: icu
URL: http://site.icu-project.org/
Version: 4.6

Description:
This directory contains the source code of ICU 4.6 for C/C++

1. It was obtained with the following:

    $ svn export --native-eol LF http://source.icu-project.org/repos/icu/icu/tags/release-4-6 icu46

2. The following directories were removed because they're not used by Chromium
   at the moment:
   as_is
   packaging
   source/extra
   source/sample
   source/layout
   source/layoutex

3. Platform header files for Linux and Mac OS X:

   - Apply platform.patch in patches directory. : It applies the upstream
     patch to platform.h.in (see http://bugs.icu-project.org/trac/ticket/8248)
     and change source/common/unicode/ptypes.h to refer to plinux.h and
     pmac.h generated below.

   - On Linux and Mac OS X, 'runConfigureICU Linux' and 'runConfigureICU MacOSX'
   are run to generate source/common/unicode/platform.h.

   - Rename it to 'plinux.h' and 'pmac.h' on Linux and Mac

   - Apply patches/pmach.h.patch on Mac to pmac.h


4. The word breaking for Chinese and Japanese were modified to use a word
   frequency list with the following patch and cjdict.txt. 
   
   - patches/segmentation.patch :
       Adds a dictionary (word-frequency)-based word breaking for CJK
       (Korean is supported in the code, but it does not do anything
        because we don't have a Korean word-list.)

   - source/data/brkitr/cjdict.txt :
       Chinese and Japanese word frequency list.
       See the file for license/copyright notice

   - source/data/brkitr/cc_edict.txt :
       the list of words derived from CC-Edict.)

   - patches/brkitr.patch
     * word.txt : Chinese/Japanese segmentation rules, Hebrew-script-specific
                  handling of U+0022, and splitting of FQDN into labels at '.'.
     * line.txt : Incorporated line_he and minor changes in CL, OP and ID
                  definitions. 
     * brklocal.mk : build file changes to drop unnecessary brkitr rule 
                     files (e.g. word_ja.txt, line_he.txt)

   If you want to run ICU tests, you have to copy source/data/brkitr/cjdict.txt
   to source/test/testdata/cjdict-truncated.txt to pass TestTrieWithValue test.

5. Converter changes : converters.patch
  - Include what we really need. See source/data/mappings/ucmlocal.txt
  - Alias and mapping changes : source/data/mappings/convrtrs.txt
  - Changes several tables and add six new tables, three of which
    are 'fake' tables for ISO-2022-CN(-Ext).
  - ucnv2022.c is modified to use 3 'fake' tables added above for
    ISO-2022-CN(-Ext).

6. Locale changes
  - patches/locale1.patch :
      Filipino, Amharic, and Swahili locales
      exemplar character set changes for CJK + 9 Indian locales
      Minor fixes for Danish, , Turkish, and Korean.

  - patches/locale2.patch :
      The minimum locale data Chrome needs for 47 languages Chrome is
      not localized to. Each locale data file has ExemplarCharacters,
      LocaleScript, layout, and the name of the language for a locale
      in its native language.

  - patches/locale3.patch : Locale build configuration files. They
    add reslocal.mk or {trns,sprep,rbnf,coll}local.mk files to 
    source/data/{coll,curr,lang.locale,curr,region,translit,zone,rbnf,sprep}.

7. Removal of unihan collation tables from data/coll/{zh,ja,ko}.txt

  - patches/unihan.patch:
    unihan collation tables are never used in Chrome/Webkit, but it takes
    about 1MB in the uncompressed ICU data file in ICU 4.2.1.

8. Build-related changes

  - patches/wpo.patch
  - patches/vscomp.patch
    (see http://bugs.icu-project.org/trac/ticket/8355 and
         http://bugs.icu-project.org/trac/ticket/8356 )
  - patches/rtti.patch : Make RTTI work without exception handling on Windows
    (see http://bugs.icu-project.org/trac/ticket/8343)
  - patches/data.build.patch :
      To remove some data files we don't use and cut down the data size.
  - patches/data.build.win.patch :
      Windows-only data build patch. Add a new target DATALIB to makedata.mak
  - patches/clang.patch: To build with Clang.
  - add an empty file (stubdatabuilt.txt) to source/stubdata

9. Pre-built data libraries are checked in.

    Before building data file on Linux, re-run runConfigureICU Linux again
    if it's run without data.build.patch in #8 above.

    'make' will fail in the 1st pass. Copy source/data/in/coll/invuca.icu
    to {BUILD_DIR_ROOT}/data/out/build/icudt46l/coll and re-run 'make'
    in {BUILD_DIR_ROOT}/data.

    - source/data/in/icudt46l.dat : Built on Linux with all the patches
      above applied,

    - windows/icudt.dll : With icudt46l.dat in place, all the patches applied
      and header files moved (#11 below), generated by building icudt_build
      project of build/icudt_build.sln on Windows. icudt46.dll is
      generated in bin/{Release,Debug} and copied to windows/icudt.dll
      and checked in. Note that we drop the version number ('46') from the
      dll name to avoind having to update our build scripts/configuration
      files everytime ICU is upgraded to a new version.

    - {mac,linux}/icudt46l_dat.S : Built on Mac and Linux with all the
      patches above applied and checked in.

    - cros/icudt46l_dat.S : Built on Linux with
      abriged locale source files in cros/data put
      in source/data. Those abridged locales files are
      for locales ChromeOS is not localized to. 

11. The header files were moved as shown below:

   source/common/unicode ==> public/common/unicode
   source/i18n/unicode   ==> public/i18n/unicode

12. Fix for msvs2010 applied:
--- D:/src/ent/src/third_party/icu/source/common/stringpiece.cpp
 (revision 78292)
+++ D:/src/ent/src/third_party/icu/source/common/stringpiece.cpp
 (working copy)
@@ -75,7 +75,7 @@
 * Visual Studios 9.0.
 * Cygwin with MSVC 9.0 also complains here about redefinition.
 */
-#if (!defined(_MSC_VER) || (_MSC_VER > 1500)) && !defined(CYGWINMSVC)
+#if (!defined(_MSC_VER) || (_MSC_VER > 1600)) && !defined(CYGWINMSVC)
 const int32_t StringPiece::npos;
 #endif