cdec 获取top-best translation

viterbi.cc

prob_t ViterbiESentence(const Hypergraph& hg, vector* result) {
  return Viterbi(hg, result);
}

viterbi.h
template
typename WeightFunction::Weight Viterbi(const Hypergraph& hg,
                   typename Traversal::Result* result,
                   const Traversal& traverse,
                   const WeightFunction& weight) {
  typedef typename Traversal::Result T;
  typedef typename WeightFunction::Weight WeightType;
  const int num_nodes = hg.nodes_.size();
  std::vector vit_result(num_nodes);
  std::vector vit_weight(num_nodes, WeightType());

  for (int i = 0; i < num_nodes; ++i) {
    const Hypergraph::Node& cur_node = hg.nodes_[i];
    WeightType* const cur_node_best_weight = &vit_weight[i];
    T*          const cur_node_best_result = &vit_result[i];

    const unsigned num_in_edges = cur_node.in_edges_.size();
    if (num_in_edges == 0) {
      *cur_node_best_weight = WeightType(1);
      continue;
    }
    HG::Edge const* edge_best=0;
    for (unsigned j = 0; j < num_in_edges; ++j) {
      const HG::Edge& edge = hg.edges_[cur_node.in_edges_[j]];
      WeightType score = weight(edge);
      for (unsigned k = 0; k < edge.tail_nodes_.size(); ++k)
        score *= vit_weight[edge.tail_nodes_[k]];
      if (!edge_best || *cur_node_best_weight < score) {
        *cur_node_best_weight = score;
        edge_best=&edge;
      }
    }
    assert(edge_best);
    HG::Edge const& edgeb=*edge_best;
    std::vector antsb(edgeb.tail_nodes_.size());
    for (unsigned k = 0; k < edgeb.tail_nodes_.size(); ++k)
      antsb[k] = &vit_result[edgeb.tail_nodes_[k]];
    traverse(edgeb, antsb, cur_node_best_result);
  }
  if (vit_result.empty())
    return WeightType(0);
  std::swap(*result, vit_result.back());
  return vit_weight.back();
}

其中traverse调用ESentenceTraversal() --> TRule::ESubstitute()