NAME

Text::MeCab - Alternate Interface To libmecab

SYNOPSIS

  use Text::MeCab;
  my $mecab = Text::MeCab->new({
    rcfile             => $rcfile,
    dicdir             => $dicdir,
    userdic            => $userdic,
    lattice_level      => $lattice_level,
    all_morphs         => $all_morphs,
    output_format_type => $output_format_type,
    partial            => $partial,
    node_format        => $node_format,
    unk_format         => $unk_format,
    bos_format         => $bos_format,
    eos_format         => $eos_format,
    input_buffer_size  => $input_buffer_size,
    allocate_sentence  => $allocate_sentence,
    nbest              => $nbest,
    theta              => $theta,
  });

  for (my $node = $mecab->parse($text); $node; $node = $node->next) {
     # See perdoc for Text::MeCab::Node for list of methods
     print $node->surface, "\n";
  }

  # use constants
  use Text::MeCab qw(:all);
  use Text::MeCab qw(MECAB_NOR_NODE);

  # want to use a command line arguments?
  my $mecab = Text::MeCab->new("--userdic=/foo/bar/baz", "-P");

  # check what mecab version we compiled against?
  print "Compiled with ", &Text::MeCab::MECAB_VERSION, "\n";

DESCRIPTION

libmecab (http://mecab.sourceforge.ne.jp) already has a perl interface built with it, so why a new module? I just feel that while a subtle difference, making the perl interface through a tied hash is just... weird.

So Text::MeCab gives you a more natural, Perl-ish way to access libmecab!

WARNING: Please note that this module is primarily targetted for libmecab >= 0.90, so if things seem to be broken and your libmecab version is below 0.90, then you might want to consider upgrading libmecab first.

Text::MeCab AND FORMATS

mecab allows users to specify an output format, via --*-format options. These are respected ONLY if you use the format() method:

  my $mecab = Text::MeCab->new({
    output_format_type => "user",
    node_format => "%m %pn"
  });

  for(my $node = $mecab->parse($text); $node; $node = $node->next) {
    print $node->format($mecab);
  }

Note that you also need to set the output_format_type parameter as well.

Text::MeCab AND SCOPING

[NOTE: The memory management issue has been changed since 0.09]

libmecab's default behavior is such that when you analyze a text and get a node back, that node is tied to the mecab "tagger" object that performed the analysis. Therefore, when that tagger is destroyed via mecab_destroy(), all nodes that are associated to it are freed as well.

Text::MeCab defaults to the same behavior, so the following won't work:

  sub get_mecab_node {
     my $mecab = Text::MeCab->new;
     my $node  = $mecab->parse($_[0]);
     return $node;
  }

  my $node = get_mecab_node($text);

By the time get_mecab_node() returns, the Text::MeCab object is DESTROY'ed, and so is $node (actually, the object exists, but it will complain when you try to access the node's internals, because the C struct that was there has already been freed).

In such cases, use the dclone() method. This will copy the *entire* node structure and create a new Text::MeCab::Node::Cloned instance.

  sub get_mecab_node {
     my $mecab = Text::MeCab->new;
     my $node  = $mecab->parse($_[0]);
     return $node->dclone();
  }

The returned Text::MeCab::Node::Cloned object is exactly the same as Text::MeCab::Node object on the surface. It just uses a different but very similar C struct underneath. It is blessed into a different namespace only because we need to use a different memory management strategy.

Do be aware of the memory issue. You WILL use up twice as much memory.

Also please note that if you try the first example, accessing the node *WILL* result in a segfault. This is *NOT* a bug: it's a feature :) While it is possible to control the memory management such that accessing a field in a node that has already expired results in a legal croak(), we do not go to the length to ensure this, because it will result in a performance penalty.

Just remember that unless you dclone() a node, then you are NOT allowed to access it when the original tagger goes out scope:

   {
       my $mecab = Text::MeCab->new;
       $node = $mecab->parse(...);
   }

   $node->surface; # segfault!!!!

Always remember to dclone() before doing this!

PERFORMANCE

Belows is the result of running tools/benchmark.pl on my PowerBook:

  daisuke@beefcake Text-MeCab$ perl tools/benchmark.pl 
               Rate      mecab text_mecab
  mecab      5.53/s         --       -63%
  text_mecab 14.9/s       170%         --

METHODS

new HASHREF | LIST

Creates a new Text::MeCab instance.

You can either specify a hashref and use named parameters, or you can use the exact command line arguments that the mecab command accepts.

Below is the list of accepted named options. See the man page for mecab for details about each option.

rcfile

dicdir

lattice_level

all_morphs

output_format_type

partial

node_format

unk_format

bos_format

eos_format

input_buffer_size

allocate_sentence

nbest

theta

parse SCALAR

Parses the given text via mecab, and returns a Text::MeCab::Node object.

SEE ALSO

http://mecab.sourceforge.ne.jp

AUTHOR

(c) 2006 Daisuke Maki <dmaki@cpan.org> All rights reserved.

cpanm Text::MeCab

perl -MCPAN -e shell
install Text::MeCab