Text::Soundex Version 3.01

NOTE: Users of Text::Soundex Version 2.x should consult the 'History'
      section at the end of this document before installing this module.
      The interface has been simplified, and existing code that takes
      advantages of Version 2.x features may need to be altered to function
      properly.

This is a perl 5 module implementing the Soundex algorithm described by 
Knuth. The algorithm is used quite often for locating a person by name
where the actual spelling of the name is not known.

This version directly supercedes the version of Text::Soundex that can be
found in the core from Perl 5.8.0 and down. (This version is a drop-in
replacement)

The algorithm used by soundex() is NOT fully compatible with the
algorithm used to index names for US Censuses. Use the soundex_nara()
subroutine to return codes for this purpose.

Basic Usage:

 Soundex is used to do a one way transformation of a name, converting
 a character string given as input into a set of codes representing
 the identifiable sounds those characters might make in the output.

 For example:

   use Text::Soundex;

   print soundex("Mark"), "\n";    # prints: M620
   print soundex("Marc"), "\n";    # prints: M620

   print soundex("Hansen"), "\n";  # prints: H525
   print soundex("Hanson"), "\n";  # prints: H525
   print soundex("Henson"), "\n";  # prints: H525

 In many situations, code such as the following:

   if ($name1 eq $name2) {
       ...
   }

 Can be substituted with:

   if (soundex($name1) eq soundex($name2)) {
       ...
   }

Installation:

 Once the archive has been unpacked then the following steps are needed
 to build, test and install the module (to be done in the directory which
 contains the Makefile.PL)

   perl Makefile.PL
   make
   make test

 If the make test succeeds then the next step may need to be run as root
 (on a Unix-like system) or with special privileges on other systems.

   make install

 If you do not want to use the XS code (for whatever reason) do the following
 instead of the above:

   perl Makefile.PL --no-xs
   make
   make test
   make install

 If any of the tests report 'not ok' and you are running perl 5.6.0 or later
 then please contact Mark Mielke <mark@mielke.cc>

History:

 Version 3.01:
     A bug with non-UTF 8 strings that contain non-ASCII alphabetic characters
     was fixed. The soundex_unicode() and soundex_nara_unicode() wrapper
     routines were included and the documentation refers the user to the
     excellent Text::Unidecode module to perform soundex encodings using
     unicode strings. The Perl versions of the routines have been further
     optimized, and correct a border case involving non-alphabetic characters
     at the beginning of the string.

 Version 3.00:
     Support for UTF-8 strings (unicode strings) is now in place. Note
     that this allows UTF-8 strings to be passed to the XS version of
     the soundex() routine. The Soundex algorithm treats characters
     outside the ascii range (0x00 - 0x7F) as if they were not
     alphabetical.

     The interface has been simplified. In order to explicitly use the
     non-XS implementation of soundex():

         use Text::Soundex ();
         $code = Text::Soundex::soundex_noxs($name);

     In order to use the NARA soundex algorithm:

         use Text::Soundex 'soundex_nara';
         $code = soundex_nara($name);

     Use of the ':NARA-Ruleset' import directive is now obsolete. To
     emulate the old behaviour:

         use Text::Soundex ();
         *soundex = \&Text::Soundex::soundex_nara;
         $code = soundex($name);

 Version 2.20:
     This version includes support for the algorithm used to index
     the U.S. Federal Censuses. There is a slight descrepancy in the
     definition for a soundex code which is not commonly known or
     recognized involved similar sounding letters being seperated
     by the characters H or W. This is defined as the NARA ruleset,
     as this descrepency was discovered by them. (Calling it "the
     US Census ruleset" was too unwieldy...)

     NARA can be found at:
          http://www.nara.gov/genealogy/

     The algorithm requested by NARA can be found at:
          http://home.utah-inter.net/kinsearch/Soundex.html

     Ways to use it in your code:

          Transparently change existing code like this:
          =============================================
          use Text::Soundex qw(:NARA-Ruleset);

          ... soundex(...) ...

                                     --

          Make the change visibly distinct like this:
          ===========================================
          use Text::Soundex qw(soundex_nara);

          ... soundex_nara(...) ...

 Version 2.00:
     This version is a full re-write of the 1.0 engine by Mark Mielke.
     The goal was for speed... and this was achieved. There is an optional
     XS module which can be used completely transparently by the user
     which offers a further speed increase of a factor of more than 7.5X.

 Version 1.00:
     This version can be found in the perl core distribution from at
     least Perl 5.8.0 and down. It was written by Mike Stok. It can be
     identified by the fact that it does not contain a $VERSION
     in the beginning of the module, and as well it uses an RCS
     tag with a version of 1.x. This version, before some perl5'ish
     packaging was introduced, was actually written for perl4.