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# Source Code for Module translate.lang.identify

      1  #!/usr/bin/env python
      2  # -*- coding: utf-8 -*-
      3  #
      4  # Copyright 2009 Zuza Software Foundation
      5  #
      6  # This file is part of translate.
      7  #
      8  # This program is free software; you can redistribute it and/or modify
      9  # it under the terms of the GNU General Public License as published by
     10  # the Free Software Foundation; either version 2 of the License, or
     11  # (at your option) any later version.
     12  #
     13  # This program is distributed in the hope that it will be useful,
     14  # but WITHOUT ANY WARRANTY; without even the implied warranty of
     15  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     16  # GNU General Public License for more details.
     17  #
     18  # You should have received a copy of the GNU General Public License
     19  # along with this program; if not, see <http://www.gnu.org/licenses/>.
     20
     21  """
     22  This module contains functions for identifying languages based on language
     23  models.
     24  """
     25
     26  from os import extsep, path
     27
     28  from translate.misc.file_discovery import get_abs_data_filename
     29  from translate.storage.base import TranslationStore
     30
     31  from ngram import NGram
     32
     33
     34 -class LanguageIdentifier(object):
     35      MODEL_DIR = get_abs_data_filename('langmodels')
     36      """The directory containing the ngram language model files."""
     37      CONF_FILE = 'fpdb.conf'
     38      """
     39      The name of the file that contains language name-code pairs
     40      (relative to C{MODEL_DIR}).
     41      """
     42
     43 -    def __init__(self, model_dir=None, conf_file=None):
     44          if model_dir is None:
     45              model_dir = self.MODEL_DIR
     46          if not path.isdir(model_dir):
     47              raise ValueError('Directory does not exist: %s' % (model_dir))
     48
     49          if conf_file is None:
     50              conf_file = self.CONF_FILE
     51          conf_file = path.abspath(path.join(model_dir, conf_file))
     52          if not path.isfile(conf_file):
     53              raise ValueError('File does not exist: %s' % (conf_file))
     54
     55          self._load_config(conf_file)
     56          self.ngram = NGram(model_dir)
     57
     58 -    def _load_config(self, conf_file):
     59          """Load the mapping of language names to language codes as given in the
     60              configuration file."""
     61          lines = open(conf_file).read().splitlines()
     62          self._lang_codes = {}
     63          for line in lines:
     64              parts = line.split()
     65              if not parts or line.startswith('#'):
     66                  continue # Skip comment- and empty lines
     67              lname, lcode = parts[0], parts[1]
     68
     69              lname = path.split(lname)[-1] # Make sure lname is not prefixed by directory names
     70              if extsep in lname:
     71                  lname = lname[:lname.rindex(extsep)] # Remove extension if it has
     72
     73              # Remove trailing '[_-]-utf8' from code
     74              if lcode.endswith('-utf8'):
     75                  lcode = lcode[:-len('-utf8')]
     76              if lcode.endswith('-') or lcode.endswith('_'):
     77                  lcode = lcode[:-1]
     78
     79              self._lang_codes[lname] = lcode
     80
     81 -    def identify_lang(self, text):
     82          """Identify the language of the text in the given string."""
     83          if not text:
     84              return None
     85          result = self.ngram.classify(text)
     86          if result in self._lang_codes:
     87              result = self._lang_codes[result]
     88          return result
     89
     90 -    def identify_source_lang(self, instore):
     91          """Identify the source language of the given translation store or
     92              units.
     93
     94              @type  instore: C{TranslationStore} or list or tuple of
     95                  C{TranslationUnit}s.
     96              @param instore: The translation store to extract source text from.
     97              @returns: The identified language's code or C{None} if the language
     98                  could not be identified."""
     99          if not isinstance(instore, (TranslationStore, list, tuple)):
    100              return None
    101
    102          text = u' '.join(unit.source for unit in instore[:50] if unit.istranslatable() and unit.source)
    103          if not text:
    104              return None
    105          return self.identify_lang(text)
    106
    107 -    def identify_target_lang(self, instore):
    108          """Identify the target language of the given translation store or
    109              units.
    110
    111              @type  instore: C{TranslationStore} or list or tuple of
    112                  C{TranslationUnit}s.
    113              @param instore: The translation store to extract target text from.
    114              @returns: The identified language's code or C{None} if the language
    115                  could not be identified."""
    116          if not isinstance(instore, (TranslationStore, list, tuple)):
    117              return None
    118
    119          text = u' '.join(unit.target for unit in instore[:200] if unit.istranslatable() and unit.target)
    120          if not text:
    121              return None
    122          return self.identify_lang(text)
    123