Added dummy implementation of EvaluateChart to SyntacticLanguageModel.

The EvaluateChart method is now required by the parent class FeatureFunction.

This implementation simply throws a runtime error,
because the syntactic language model is incremental in nature,
and as such is not well defined for chart parsing algorithms.

moses/src/SyntacticLanguageModel.h

@@ -4,7 +4,7 @@
 #define moses_SyntacticLanguageModel_h
 
 #include "FeatureFunction.h"
-
+#include <stdexcept>
 
 class YModel; // hidden model
 class XModel; // observed model
@@ -35,6 +35,13 @@ namespace Moses
 		      const FFState* prev_state,
 		      ScoreComponentCollection* accumulator) const;
 
+    FFState* EvaluateChart(const ChartHypothesis& cur_hypo,
+                           int featureID,
+                           ScoreComponentCollection* accumulator) const {
+      throw std::runtime_error("Syntactic LM can only be used with phrase-based decoder.");
+    }
+
+
     //    double perplexity();
 
   private: