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diff --git a/klm/lm/facade.hh b/klm/lm/facade.hh
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+++ b/klm/lm/facade.hh
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+#ifndef LM_FACADE__
+#define LM_FACADE__
+
+#include "lm/virtual_interface.hh"
+#include "util/string_piece.hh"
+
+#include <string>
+
+namespace lm {
+namespace base {
+
+// Common model interface that depends on knowing the specific classes. 
+// Curiously recurring template pattern.  
+template <class Child, class StateT, class VocabularyT> class ModelFacade : public Model {
+  public:
+    typedef StateT State;
+    typedef VocabularyT Vocabulary;
+
+    // Default Score function calls FullScore.  Model can override this.  
+    float Score(const State &in_state, const WordIndex new_word, State &out_state) const {
+      return static_cast<const Child*>(this)->FullScore(in_state, new_word, out_state).prob;
+    }
+
+    /* Translate from void* to State */
+    FullScoreReturn FullScore(const void *in_state, const WordIndex new_word, void *out_state) const {
+      return static_cast<const Child*>(this)->FullScore(
+          *reinterpret_cast<const State*>(in_state),
+          new_word,
+          *reinterpret_cast<State*>(out_state));
+    }
+    float Score(const void *in_state, const WordIndex new_word, void *out_state) const {
+      return static_cast<const Child*>(this)->Score(
+          *reinterpret_cast<const State*>(in_state),
+          new_word,
+          *reinterpret_cast<State*>(out_state));
+    }
+
+    const State &BeginSentenceState() const { return begin_sentence_; }
+    const State &NullContextState() const { return null_context_; }
+    const Vocabulary &GetVocabulary() const { return *static_cast<const Vocabulary*>(&BaseVocabulary()); }
+
+  protected:
+    ModelFacade() : Model(sizeof(State)) {}
+
+    virtual ~ModelFacade() {}
+
+    // begin_sentence and null_context can disappear after.  vocab should stay.  
+    void Init(const State &begin_sentence, const State &null_context, const Vocabulary &vocab, unsigned char order) {
+      begin_sentence_ = begin_sentence;
+      null_context_ = null_context;
+      begin_sentence_memory_ = &begin_sentence_;
+      null_context_memory_ = &null_context_;
+      base_vocab_ = &vocab;
+      order_ = order;
+    }
+
+  private:
+    State begin_sentence_, null_context_;
+};
+
+} // mamespace base
+} // namespace lm
+
+#endif // LM_FACADE__