Source Code for Module nltk.yamltags

 1  import yaml 
 2   
 3  """ 
 4  Register YAML tags in the NLTK namespace with the YAML loader, by telling it 
 5  what module and class to look for. 
 6   
 7  NLTK uses simple '!' tags to mark the types of objects, but the fully-qualified 
 8  "tag:nltk.sourceforge.net,2007:" prefix is also accepted in case anyone ends up 
 9  using it. 
10  """ 
11   
12 -def custom_import(name): 
13      components = name.split('.') 
14      module_path = '.'.join(components[:-1]) 
15      mod = __import__(module_path) 
16      for comp in components[1:]: 
17          mod = getattr(mod, comp) 
18      return mod 
19   
20 -def metaloader(classpath): 
21      def loader(*args, **kwds): 
22          classref = custom_import(classpath) 
23          return classref.from_yaml(*args, **kwds) 
24      return loader 
25   
26 -def register_tag(tag, classpath): 
27      yaml.add_constructor(u'!'+tag, metaloader(classpath)) 
28      yaml.add_constructor(u'tag:nltk.sourceforge.net,2007:'+tag, 
29                           metaloader(classpath)) 
30   
31  register_tag(u'tag.Unigram', 'nltk.tag.unigram.Unigram') 
32  register_tag(u'tag.Brill', 'nltk.tag.brill.Brill') 
33   
34  __all__ = ['custom_import', 'metaloader', 'register_tag'] 
35