package Text::Capitalize;

=head1 NAME

Text::Capitalize - capitalize strings ("to WORK AS titles" becomes "To Work as Titles")

=head1 SYNOPSIS

   use Text::Capitalize;

   print capitalize( "...and justice for all" ), "\n";
      ...And Justice For All

   print capitalize_title( "...and justice for all" ), "\n";
      ...And Justice for All

   print capitalize_title( "agent of SFPUG", PRESERVE_ALLCAPS=>1 ), "\n";
      Agent of SFPUG

   print capitalize_title( "the ring:  symbol or cliche?",
                           PRESERVE_WHITESPACE=>1 ), "\n";
      The Ring:  Symbol or Cliche?
      (Note, double-space after colon is still there.)

   # To work on international characters, may need to set locale
   use Env qw( LANG );
   $LANG = "en_US";
   print capitalize_title( "über maus" ), "\n";
      Über Maus

   use Text::Capitalize qw( scramble_case );
   print scramble_case( 'It depends on what you mean by "mean"' );
      It dEpenDS On wHAT YOu mEan by "meAn".

=head1 ABSTRACT

  Text::Capitalize is for capitalizing strings in a manner
suitable for use in titles.

=head1 DESCRIPTION

Text::Capitalize provides some routines for B<title-like>
formatting of strings.

The simple B<capitalize> function just makes the inital character
of each word uppercase, and forces the rest to lowercase.

The B<capitalize_title> function applies English title case rules
(discussed below) where only the "important" words are supposed
to be capitalized.  There are also some customization features
provided to allow the user to choose variant rules.

Comparing B<capitalize> and B<captialize_title>:

  Input:             "lost watches of splitsville"
  capitalize:        "Lost Watches Of Splitsville"
  capitalize_title:  "Lost Watches of Splitsville"

Some examples of formatting with B<capitalize_title>:

  Input:             "KiLLiNG TiMe"
  capitalize_title:  "Killing Time"

  Input:             "we have come to wound the autumnal city"
  capitalize_title:  "We Have Come to Wound the Autumnal City"

  Input:             "ask for whom they ask for"
  captialize_title:  "Ask for Whom They Ask For"

Text::Capitalize also provides some functions for special effects
such as B<scramble_case>, which typically would be used for this sort
of transformation:

  Input:            "get whacky"
  scramble_case:    "gET wHaCkY"  (or something similar)


=head1 EXPORTS

=head2 default exports

=over

=cut

use 5.006;
use strict;
use warnings;
use utf8;

# use locale;
use Carp;
use Exporter;
use vars qw(@ISA @EXPORT @EXPORT_OK $VERSION);

use vars qw($DEBUG);
$DEBUG = 0;

@ISA		= qw(Exporter);
@EXPORT		= qw(capitalize capitalize_title);
@EXPORT_OK      = qw(@exceptions
                     %defaults_capitalize_title
                     scramble_case
                     random_case
                     zippify_case
                     capitalize_title_original
                    );
$VERSION	= '1.3';

# Define the pattern to match "exceptions": the minor words
# that don't usually get capitalized in titles (used by capitalize_title)
use vars qw(@exceptions);
@exceptions = qw(
     a an the
     and or nor for but so yet
     to of by at for but in with has
     de von
  );

# Define the default arguments for the capitalize_title function
use vars qw(%defaults_capitalize_title);
%defaults_capitalize_title = (
             PRESERVE_WHITESPACE => 0,
             PRESERVE_ALLCAPS    => 0,
             PRESERVE_ANYCAPS    => 0,
             NOT_CAPITALIZED     => \@exceptions,
            );


# Defining patterns to match "words" and "sentences" (used by capitalize_title)

use vars qw($word_rule $sentence_rule);
use vars qw($anything $ellipsis $dot $qmark $emdash $terminator $ws);

$word_rule =  qr{ ([^\w\s]*)   # $1 - leading punctuation
                               #   (e.g. ellipsis, leading apostrophe)
                   ([\w']*)    # $2 - the word itself (includes non-leading apostrophes)
                   ([^\w\s]*)  # $3 - trailing punctuation
                               #   (e.g. comma, ellipsis, period)
                   (\s*)       # $4 - trailing whitespace
                               #   (usually " ", though at EOL prob "")
                 }x ;

# Pieces for the $sentence_rule
$anything =    qr{.*?};
$ellipsis =    qr{\Q...};
$dot =         qr{\Q.};
$qmark =       qr{\Q?};
$emdash =      qr{\Q--};
$terminator =  qr{$ellipsis|$dot|$qmark|!|:|$emdash|$};
$ws =          qr{\s*};

$sentence_rule =
  qr{  (    $anything       # anything up to...
            $terminator     # any sentence terminator (*or* the EOS)
            $ws             # trailing whitespace, if any
       )                    # all captured to $1
    }ox;


=item capitalize

Makes the inital character of each word uppercase, and forces the
rest to lowercase.

The original routine by Stanislaw Y. Pusep.

=cut

sub capitalize {
   local $_ = shift;
   s/\b(.*?)\b/$1 eq uc $1 ? $1 : "\u\L$1"/ge;
   return $_;
}

=item capitalize_title

Applies English title case rules (See L<BACKGROUND>) where only the
"important" words are supposed to be capitalized.

The one required argument is the string to be capitalized.

Some customization options may be passed in as pairs of names and
values following the required argument.

The following customizations are allowed:

Boolean:

  PRESERVE_WHITESPACE
  PRESERVE_ALLCAPS
  PRESERVE_ANYCAPS

Array reference:

  NOT_CAPITALIZED

See L<Customizing the Exceptions to Capitalization>.

=cut

sub capitalize_title {
  my $string = shift;

  my %args = (%defaults_capitalize_title,
              @_         # imports the argument pair list, if any
             );

  # Checking for spelling errors in options
  foreach (keys %args) {
    unless (exists $defaults_capitalize_title{$_}) {
      carp "Bad option $_\n";
    }
  }

  my $keep_ws =       $args{ PRESERVE_WHITESPACE };
  my $keep_acronyms = $args{ PRESERVE_ALLCAPS };
  my $keep_mixups =   $args{ PRESERVE_ANYCAPS };

  my $exceptions_or = join '|', @{ $args{ NOT_CAPITALIZED } };
  my $exception_rule = qr{^(?:$exceptions_or)$}i;

  my $new_string = "";

  ### Processing each sentence (titles can have multiple sentences)
  while ( $string =~ /$sentence_rule/g ) {
    my $sentence = $1;
    my $new_sentence = "";

    my @words = ();
    # The array @words will contain records about each word, including its
    # surroundings: trailing whitespace and leading or trailing punctuation
    # (for cases such as "...and", "'em", "and...", "F.B.I.")
    # Each row is an aref of: $punct_leading, $word, $punct_trailing, $spc

    my $i = 0;
    while ($sentence =~ /$word_rule/g) {
      # If we've matched something, load it (pattern yields an empty match at eos)
      if ( ($2 ne '') or $1 or $3 or ($4 ne '') ) {
        $words[ $i ] = [ $1, $2, $3, $4 ];
        $i++;
      }
    }

    ### Processing each word
    my ($punct_leading, $word, $punct_trailing, $spc);
    my $first = 0;
    my $last = $#words;
    for ( $i = $first; $i <= $last; $i++ ) {
      {
        # (easier to know when you're doing the first and last using explicit counter)
        ($punct_leading, $word, $punct_trailing, $spc) = ( @{ $words[$i] } );

        unless ($keep_ws) {     # collapse whitespace
          $spc = " " if (length($spc) > 0);
        }

        # Keep words with any capitals (e.g. "iMac") if they're being passed through.
        next if ( ($keep_mixups)   && ( $word =~ m{[[:upper:]]} ) );

        # Keep all uppercase words if they're being passed through.
        next if ( ($keep_acronyms) && ( $word =~ m{^[[:upper:]]+$}) );

        # Fugliness to get some French names to work, e.g. "d'Alembert", "l'Hospital"
        if ( $word =~ m{^[dl]'}) {
          $word =~ s{ ^(d') (\w) }{ lc($1) . uc($2) }iex;
          $word =~ s{ ^(l') (\w) }{ lc($1) . uc($2) }iex;

          # But upcase first char if first or last word
          if ( ($i == $first) or ($i == $last) ) {
            $word = ucfirst( $word );
          }
          next;
        }

        # The first word and the last are always capitalized
        if ( ($i == $first) or ($i == $last) ) {
          $word = ucfirst( lc( $word ) );
          next;
        }

        # upcase all words, except for the exceptions
        if ( $word =~ m{$exception_rule} ) {
          $word = lc( $word );
        } else {
          $word = ucfirst( lc( $word ) );
        }

      } continue {              # Append word to the new sentence
        $new_sentence .=  $punct_leading . $word . $punct_trailing . $spc;
      }
    }                           # end of per word for loop

    $new_string .= $new_sentence;
  }                             # end of per sentence loop.

  # Delete leading/trailing spaces, unless preserving whitespace,
  # (Doing as final step to avoid dropping spaces *between* sentences.)
  unless ($keep_ws) {
    $new_string =~ s|^\s+||;
    $new_string =~ s|\s+$||;
  }

  return $new_string;
} # end sub capitalize_title



=back

=head2 optional exports

=over

=item @exceptions

The list of minor words that don't usually get capitalized in
titles (used by L<capitalize_title>).  Defaults to:

     a an the
     and or nor for but so yet
     to of by at for but in with has
     de von

=item %defaults_capitalize_title

Defines the default arguments for the capitalize_title function
Initially, this is set-up to shut off the features
PRESERVE_WHITESPACE, PRESERVE_ALLCAPS and PRESERVE_ANYCAPS;
it also has L<@exceptions> as the NOT_CAPITALIZED list.

=item scramble_case

This routine provides a special effect: sCraMBliNg tHe CaSe

The algorithm here uses a modified probability distribution to get
a weirder looking effect than simple randomization such as with L<random_case>.

For a discussion of the algorithm, see L<SPECIAL EFFECTS>.

=cut

# Instead of initializing $uppers, $downers to zero, using fudged
# initial counts to
#   (1) provide an initial bias against leading with uppercase,
#   (2) eliminate need to watch for division by zero on $tweak below.

# Rather than "int(rand(2))" which generates a 50/50 distribution of 0s and 1s,
# we're using "int(rand(1+$tweak))" where $tweak will
# provide a restoring force back to the average
# So here we want $tweak:
#    to go to 1 when you approach $uppers = $downers
#    to be larger than 1 if $downers > $uppers
#    to be less than 1 if $uppers > $downers
# A simple formula that does this:
#      $uppity = int( rand( 1 + $downers/$uppers) );
# The alternative (proposed by Randal Schwartz) is no real speed improvement:
#      $uppity = rand( $uppers + $downers ) > $uppers;
# (though there are no worries about divide by zero there).

# Note that this benchmarks faster:
#   @chars = split //, $string;
# Than:
#   @chars = split /(?<=[[:alpha:]])/, $string;

sub scramble_case {
   my $string = shift;
   my (@chars, $uppity, $newstring, $total, $uppers, $downers, $tweak);

   @chars = split //, $string;

   $uppers = 2;
   $downers = 1;
   foreach my $c (@chars) {
      $uppity = int( rand( 1 + $downers/$uppers) );

      if ($uppity) {
         $c = uc($c);
         $uppers++;
       } else {
         $c = lc($c);
         $downers++;
       }
   }
   $newstring = join '', @chars;
   return $newstring;
}

=item random_case

Randomizes the case of each character with a 50-50 chance
of each one becoming upper or lower case.

=cut

sub random_case {
   local $_;
   my $string = shift;
   my (@chars, $uppity, $newstring);
   @chars = split //, $string;

   foreach (@chars) {
      $uppity = int ( rand(2) ); # simple, 50-50 random pick

      if ($uppity) {
         $_ = uc;
       } else {
         $_ = lc;
       }
   }
   $newstring = join '', @chars;
   return $newstring;
}

=item zippify_case

Function to provide a special effect: "RANDOMLY upcasing WHOLE WORDS at a TIME".

This uses a similar algorithm to L<scramble_case>, though it also
ignores words on the L<@exceptions> list, just as L<capitalize_title> does.

=cut

sub zippify_case {
   my $string = shift;
   my (@words, $uppity, $newstring, $total, $uppers, $downers, $tweak);
   @words = split /\b/, $string;

   $uppers = 1;
   $downers = 5;
   WORD: foreach my $word (@words) {
      foreach (@exceptions) {
        next WORD if m/\Q$word\E/i;
      }

      # a modified "random" distribution with fewer "streaks" than normal.
      $uppity = int( rand( 1 + $downers/$uppers ) );

      if ($uppity) {
         $word = uc($word);
         $uppers++;
       } else {
         $word = lc($word);
         $downers++;
       }
   }
   $newstring = join '', @words;
   return $newstring;
}





1;

=back

=head1 BACKGROUND

The capitalize_title function tries to do the right thing by
default: adjust an arbitrary chunk of text so that it can be used
as a title.  But as with many aspects of the human languages, it
is extremely difficult to come up with a set of programmatic
rules that will cover all cases.

=head2 Words that don't get capitalized

This web page:

  http://www.continentallocating.com/World.Literature/General2/LiteraryTitles2.htm

presents some admirably clear rules for capitalizing titles:

  ALL words in EVERY title are capitalized except
  (1) a, an, and the,
  (2) two and three letter conjunctions (and, or, nor, for, but, so, yet),
  (3) prepositions.
  Exceptions:  The first and last words are always capitalized even
  if they are among the above three groups.

But consider the case:

  "It Waits Underneath the Sea"

Should the word "underneath" be downcased because it's a preposition?
Most English speakers would be surprised to see it that way.
Consequently, the default list of exceptions to capitalization in this module
only includes the shortest of the common prepositions (to of by at for but in).

The default entries on the exception list are:

     a an the
     and or nor for but so yet
     to of by at for but in with has
     de von

The observant may note that the last row is not composed of English
words.  The honorary "de" has been included in honor of "Honoré de
Balzac".  And "von" was added for the sake of equal time.


=head2 Customizing the Exceptions to Capitalization

If you have different ideas about the "rules" of English
(or perhaps if you're trying to use this code with another
language with different rules) you might like to substitute
a new exception list of your own:

  capitalize_title( "Dude, we, like, went to Old Slavy, and uh, they didn't have it",
                     NOT_CAPITALIZED => [ qw( uh duh huh wha like man you know ) ] );

This should return:

   Dude, We, like, Went To Old Slavy, And uh, They Didn't Have It

Less radically, you might like to simply add a word to the list,
for example "from":

   use Text::Capitalize 0.2 qw( capitalize_title @exceptions );
   push @exceptions, "from";

   print capitalize_title( "fungi from yuggoth",
                           NOT_CAPITALIZED => \@exceptions);

This should output:

    Fungi from Yuggoth

=head2 All Uppercase Words

In order to work with a wide range of input strings, by default
capitalize_title presumes that upper-case input needs to be adjusted
(e.g. "DOOM APPROACHES!" would become "Doom Approaches!").  But, this
doesn't allow for the possibilities such as an acronym in a title
(e.g. "RAM Prices Plummet" ideally should not become "Ram Prices
Plummet").  If the PRESERVE_ALLCAPS option is set, then it will be
presumed that an all-uppercase word is that way for a reason, and
will be left alone:

   print capitalize_title( "ram more RAM down your throat",
                           PRESERVE_ALLCAPS => 1 );

This should output:

      Ram More RAM Down Your Throat

=head2 Preserving Any Usage of Uppercase for Mixed-case Words

There are some other odd cases that are difficult to handle well,
notably mixed-case words such as "iMac", "CHiPs", and so on.  For
these purposes, a PRESERVE_ANYCAPS option has been provided which
presumes that any usage of uppercase is there for a reason, in which
case the entire word should be passed through untouched.  With
PRESERVE_ANYCAPS on, only the case of all lowercase words will ever
be adjusted:

   print capitalize_title( "TLAs i have known and loved",
                       PRESERVE_ANYCAPS => 1 );

This should output:

   TLAs I Have Known and Loved

   print capitalize_title( "the next iMac: just another NeXt?",
                            PRESERVE_ANYCAPS => 1);

This should output:

   The Next iMac: Just Another NeXt?


=head2 Handling Whitespace

By default, the capitalize_title function presumes that you're trying
to clean up potential title strings. As an extra feature it collapses
multiple spaces and tabs into single spaces.  If this feature doesn't
seem desirable and you want it to literally restrict itself to
adjusting capitalization, you can force that behavior with the
PRESERVE_WHITESPACE option:

   print capitalize_title( "it came from texas:  the new new world order?",
                           PRESERVE_WHITESPACE => 1);

This should output:

      It Came From Texas:  The New New World Order?

(Note: the double-space after the colon is still there.)

=head2 Comparison to Text::Autoformat

As you might expect, there's more than one way to do this,
and these two pieces of code perform very similar functions:

   use Text::Capitalize 0.2;
   print capitalize_title( $t ), "\n";

   use Text::Autoformat;
   print autoformat { case => "highlight", right => length( $t ) }, $t;

Note: with autoformat, supplying the length of the string as the
"right margin" is much faster than plugging in an arbitrarily large
number.  There doesn't seem to be any other way of turning off
line-breaking (e.g. by using the "fill" parameter) though possibly
there will be in the future.

As of this writing, "capitalize_title" has some advantages:

=over

=item 1.

It works on characters outside the English 7-bit ASCII
range, for example with my locale setting (en_US) the
ISO-8859-1 International characters are handled correctly,
so that "über maus" becomes "Über Maus".

=item 2.

Minor words following leading punctuation become upper case:

   "...And Justice for All"

=item 3.

It works with multiple sentence input (e.g. "And sooner. And later."
should probably not be "And sooner. and later.")

=item 4.

The list of minor words is more extensive (i.e. includes: so, yet, nor),
and is also customizable.

=item 5.

There's a way of preserving acronyms via the PRESERVE_ALLCAPS option
and similarly, mixed-case words ("iMac", "NeXt", etc") with the
PRESERVE_ANYCAPS option.

=item 6.

capitalize_title is roughly ten times faster.

=back

Another difference is that Text::Autoformat's "highlight"
always preserves whitespace something like capitalize_title
does with the PRESERVE_WHITESPACE option set.

However, it should be pointed out that Text::Autoformat is under
active maintenance by Damian Conway.  It also does far more than
this module, and you may want to use it for other reasons.

=head2 Still more ways to do it

Late breaking news: The second edition of the Perl Cookbook
has just come out.  It now includes: "Properly Capitalizing
a Title or Headline" as recipe 1.14.  You should
familiarize yourself with this if you want to become a true
master of all title capitalization routines.

(And I see that recipe 1.13 includes a "randcap" program as
an example, which as it happens does something like the
random_case function described below...)

=head1 SPECIAL EFFECTS

Some functions have been provided to make strings look weird
by scrambling their capitalization ("lIKe tHiS"):
random_case and scramble_case.  The function "random_case"
does a straight-forward randomization of capitalization so
that each letter has a 50-50 chance of being upper or lower
case.  The function "scramble_case" performs a very similar
function, but does a slightly better job of producing something
"weird-looking".

The difficulty is that there are differences between human
perception of randomness and actual randomness.  Consider
the fact that of the sixteen ways that the four letter word
"word" can be capitalized, three of them are rather boring:
"word", "Word" and "WORD".  To make it less likely that
scramble_case will produce dull output when you want "weird"
output, a modified probability distribution has been used
that records the history of previous outcomes, and tweaks
the likelihood of the next decision in the opposite
direction, back toward the expected average.  In effect,
this simulates a world in which the Gambler's Fallacy is
correct ("Hm... red has come up a lot, I bet that black is
going to come up now."). "Streaks" are much less likely
with scramble_case than with random_case.

Additionally, with scramble_case the probability that the
first character of the input string will become upper-case
has been tweaked to less than 50%.  (Future versions may
apply this tweak on a per-word basis rather than just on a
per-string basis).

There is also a function that scrambles capitalization on
a word-by-word basis called "zippify_case", which should produce output
like: "In my PREVIOUS life i was a LATEX-novelty REPAIRMAN!"


=head1 EXPORT

By default, this version of the module provides the two
functions capitalize and capitalize_title.  Future versions
will have no further additions to the default export list.

Optionally, the following functions may also be exported:

=over

=item scramble_case

A function to scramble capitalization in a wEiRD loOOkInG wAy.
Supposed to look a little stranger than the simpler random_case
output

=item random_case

Function to randomize capitalization of each letter in the
string.  Compare to "scramble_case"

=item zippify_case

A function like "scramble_case" that acts on a word-by-word basis
(Somewhat LIKE this, YOU know?).

=back

It is also possible to export the following variables:

=over

=item @exceptions

The list of minor words that capitalize_title uses by default to
determine the exceptions to capitalization.

=item %defaults-capitalize_title

The hash of allowed arguments (with defaults) that the
capitalize_title function uses.

=back

=head1 BUGS

1. In capitalize_title, quoted sentence terminators are
treated as actual sentence breaks, e.g. in this case:

     'say "yes but!" and "know what?"'

The program sees the ! and effectively treats this as two
separate sentences: the word "but" becomes "But" (under the
rule that last words must always be uppercase, even if they're
on the exception list) and the word "and" becomes "And" (under
the first word rule).

2. There's no good way to automatically handle names like
"McCoy".  Consider the difficulty of disambiguating "Macadam
Roads" from "MacAdam Rode".  If you need to solve problems like
this, consider using the case_surname function of Lingua::En::NameParse.

3. In general, Text::Capitalize is a very parochial
English oriented module that looks like it belongs in the
"Lingua::En::*" tree.

4. There's currently no way of doing a PRESERVE_ANYCAPS
that *also* adjusts capitalization of words on the exception
list, so that "iMac Or iPod" would become "iMac or iPod".


=head1 SEE ALSO

L<Text::Autoformat>

"The Perl Cookbook", second edition, recipes 1.13 and 1.14

L<Lingua::En::NameParse>

About "scramble_case":
L<http://obsidianrook.com/devnotes/talks/esthetic_randomness/>

=head1 VERSION

Version 0.9

=head1 AUTHORS

   Joseph M. Brenner
      E-Mail:   doom@kzsu.stanford.edu
      Homepage: http://obsidianrook.com/map

   Stanislaw Y. Pusep  (who wrote "capitalize")
      E-Mail:	stanis@linuxmail.org
      ICQ UIN:	11979567
      Homepage:	http://sysdlabs.hypermart.net/

And many thanks (for feature suggestions and code examples) to:

    Belden Lyman, Yary Hcluhan, Randal Schwartz

=head1 COPYRIGHT AND LICENSE

Copyright 2003 by Joseph Brenner. All rights reserved.

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=cut