From f568b392f82fd94b788a1b38094855234d318205 Mon Sep 17 00:00:00 2001
From: Kenneth Heafield <github@kheafield.com>
Date: Sun, 14 Oct 2012 10:46:34 +0100
Subject: Update to faster but less cute search

---
 klm/search/edge_queue.hh | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 klm/search/edge_queue.hh

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

diff --git a/klm/search/edge_queue.hh b/klm/search/edge_queue.hh
new file mode 100644
index 00000000..187eaed7
--- /dev/null
+++ b/klm/search/edge_queue.hh
@@ -0,0 +1,73 @@
+#ifndef SEARCH_EDGE_QUEUE__
+#define SEARCH_EDGE_QUEUE__
+
+#include "search/edge.hh"
+#include "search/edge_generator.hh"
+#include "search/note.hh"
+
+#include <boost/pool/pool.hpp>
+#include <boost/pool/object_pool.hpp>
+
+#include <queue>
+
+namespace search {
+
+template <class Model> class Context;
+
+class EdgeQueue {
+  public:
+    explicit EdgeQueue(unsigned int pop_limit_hint);
+
+    PartialEdge &InitializeEdge() {
+      return *take_;
+    }
+
+    void AddEdge(unsigned char arity, Note note) {
+      generate_.push(edge_pool_.construct(*take_, arity, note));
+      take_ = static_cast<PartialEdge*>(partial_edge_pool_.malloc());
+    }
+
+    bool Empty() const { return generate_.empty(); }
+
+    /* Generate hypotheses and send them to output.  Normally, output is a
+     * VertexGenerator, but the decoder may want to route edges to different
+     * vertices i.e. if they have different LHS non-terminal labels.  
+     */
+    template <class Model, class Output> void Search(Context<Model> &context, Output &output) {
+      int to_pop = context.PopLimit();
+      while (to_pop > 0 && !generate_.empty()) {
+        EdgeGenerator *top = generate_.top();
+        generate_.pop();
+        PartialEdge *ret = top->Pop(context, partial_edge_pool_);
+        if (ret) {
+          output.NewHypothesis(*ret, top->GetNote());
+          --to_pop;
+          if (top->TopScore() != -kScoreInf) {
+            generate_.push(top);
+          }
+        } else {
+          generate_.push(top);
+        }
+      }
+      output.FinishedSearch();
+    }
+
+  private:
+    boost::object_pool<EdgeGenerator> edge_pool_;
+
+    struct LessByTopScore : public std::binary_function<const EdgeGenerator *, const EdgeGenerator *, bool> {
+      bool operator()(const EdgeGenerator *first, const EdgeGenerator *second) const {
+        return first->TopScore() < second->TopScore();
+      }
+    };
+
+    typedef std::priority_queue<EdgeGenerator*, std::vector<EdgeGenerator*>, LessByTopScore> Generate;
+    Generate generate_;
+
+    boost::pool<> partial_edge_pool_;
+
+    PartialEdge *take_;
+};
+
+} // namespace search
+#endif // SEARCH_EDGE_QUEUE__
-- 
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