Provides abstraction and support for the language model feature function typically used in hierarchical phrase-based decoding for statistical machine translation. The classes contained within this directory are responsible for two tasks: implementing the feature function, and representing the language model itself. The class `LanguageModelFF` implements the feature function by exending the class `DefaultStatefulFF`. One of these is instantiated for each language model present in the decoder. The language models themselves are implemented as a combination of an interface (`NGramLanguageModel`), a default implementation (`DefaultNgramLangaugeModel`), and an abstract implementation of the default (`AbstractLM`).

  DefaultStatefulFF
  |- LanguageModelFF

  DefaultNgramLanguageModel implements interface NGramLanguageModel
  |- AbstractLM