From de53e2e98acd0e2d07efb39bef430bd598908aa8 Mon Sep 17 00:00:00 2001
From: Kenneth Heafield <github@kheafield.com>
Date: Fri, 14 Dec 2012 12:39:04 -0800
Subject: Updated incremental, updated kenlm.  Incremental assumes <s>

---
 klm/search/vertex_generator.hh | 72 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 62 insertions(+), 10 deletions(-)

(limited to 'klm/search/vertex_generator.hh')

diff --git a/klm/search/vertex_generator.hh b/klm/search/vertex_generator.hh
index 60e86112..da563c2d 100644
--- a/klm/search/vertex_generator.hh
+++ b/klm/search/vertex_generator.hh
@@ -2,9 +2,11 @@
 #define SEARCH_VERTEX_GENERATOR__
 
 #include "search/edge.hh"
+#include "search/types.hh"
 #include "search/vertex.hh"
 
 #include <boost/unordered_map.hpp>
+#include <boost/version.hpp>
 
 namespace lm {
 namespace ngram {
@@ -15,21 +17,44 @@ class ChartState;
 namespace search {
 
 class ContextBase;
-class Final;
 
-class VertexGenerator {
+#if BOOST_VERSION > 104200
+// Parallel structure to VertexNode.  
+struct Trie {
+  Trie() : under(NULL) {}
+
+  VertexNode *under;
+  boost::unordered_map<uint64_t, Trie> extend;
+};
+
+void AddHypothesis(ContextBase &context, Trie &root, const NBestComplete &end);
+
+#endif // BOOST_VERSION
+
+// Output makes the single-best or n-best list.   
+template <class Output> class VertexGenerator {
   public:
-    VertexGenerator(ContextBase &context, Vertex &gen);
+    VertexGenerator(ContextBase &context, Vertex &gen, Output &nbest) : context_(context), gen_(gen), nbest_(nbest) {
+      gen.root_.InitRoot();
+    }
 
     void NewHypothesis(PartialEdge partial) {
-      const lm::ngram::ChartState &state = partial.CompletedState();
-      std::pair<Existing::iterator, bool> ret(existing_.insert(std::make_pair(hash_value(state), partial)));
-      if (!ret.second && ret.first->second < partial) {
-        ret.first->second = partial;
-      }
+      nbest_.Add(existing_[hash_value(partial.CompletedState())], partial);
     }
 
-    void FinishedSearch();
+    void FinishedSearch() {
+#if BOOST_VERSION > 104200
+      Trie root;
+      root.under = &gen_.root_;
+      for (typename Existing::iterator i(existing_.begin()); i != existing_.end(); ++i) {
+        AddHypothesis(context_, root, nbest_.Complete(i->second));
+      }
+      existing_.clear();
+      root.under->SortAndSet(context_);
+#else
+      UTIL_THROW(util::Exception, "Upgrade Boost to >= 1.42.0 to use incremental search.");
+#endif
+    }
 
     const Vertex &Generating() const { return gen_; }
 
@@ -38,8 +63,35 @@ class VertexGenerator {
 
     Vertex &gen_;
 
-    typedef boost::unordered_map<uint64_t, PartialEdge> Existing;
+    typedef boost::unordered_map<uint64_t, typename Output::Combine> Existing;
     Existing existing_;
+
+    Output &nbest_;
+};
+
+// Special case for root vertex: everything should come together into the root
+// node.  In theory, this should happen naturally due to state collapsing with
+// <s> and </s>.  If that's the case, VertexGenerator is fine, though it will
+// make one connection.  
+template <class Output> class RootVertexGenerator {
+  public:
+    RootVertexGenerator(Vertex &gen, Output &out) : gen_(gen), out_(out) {}
+
+    void NewHypothesis(PartialEdge partial) {
+      out_.Add(combine_, partial);
+    }
+
+    void FinishedSearch() {
+      gen_.root_.InitRoot();
+      NBestComplete completed(out_.Complete(combine_));
+      gen_.root_.SetEnd(completed.history, completed.score);
+    }
+
+  private:
+    Vertex &gen_;
+    
+    typename Output::Combine combine_;
+    Output &out_;
 };
 
 } // namespace search
-- 
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