From 32dcedf28adef39ddd07aaa1ad49e3e73e50b98e Mon Sep 17 00:00:00 2001
From: Chris Dyer <redpony@gmail.com>
Date: Tue, 1 Apr 2014 21:52:15 -0400
Subject: deal with pass through rules

---
 decoder/tree2string_translator.cc | 47 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/decoder/tree2string_translator.cc b/decoder/tree2string_translator.cc
index 6f65658e..4cd584fb 100644
--- a/decoder/tree2string_translator.cc
+++ b/decoder/tree2string_translator.cc
@@ -101,6 +101,7 @@ namespace std {
 struct Tree2StringTranslatorImpl {
   vector<boost::shared_ptr<Tree2StringGrammarNode>> root;
   bool add_pass_through_rules;
+  unsigned remove_grammars;
   Tree2StringTranslatorImpl(const boost::program_options::variables_map& conf) :
       add_pass_through_rules(conf.count("add_pass_through_rules")) {
     if (conf.count("grammar")) {
@@ -114,11 +115,56 @@ struct Tree2StringTranslatorImpl {
       }
     }
   }
+
+  void CreatePassThroughRules(const cdec::TreeFragment& tree) {
+    static const int kFID = FD::Convert("PassThrough");
+    root.resize(root.size() + 1);
+    root.back().reset(new Tree2StringGrammarNode);
+    ++remove_grammars;
+    for (auto& prod : tree.nodes) {
+      ostringstream os;
+      vector<int> rhse, rhsf;
+      int ntc = 0;
+      int lhs = -(prod.lhs & cdec::ALL_MASK);
+      os << '(' << TD::Convert(-lhs);
+      for (auto& sym : prod.rhs) {
+        os << ' ';
+        if (cdec::IsTerminal(sym)) {
+          os << TD::Convert(sym);
+          rhse.push_back(sym);
+          rhsf.push_back(sym);
+        } else {
+          unsigned id = tree.nodes[sym & cdec::ALL_MASK].lhs & cdec::ALL_MASK;
+          os << '[' << TD::Convert(id) << ']';
+          rhsf.push_back(-id);
+          rhse.push_back(-ntc);
+          ++ntc;
+        }
+      }
+      os << ')';
+      cdec::TreeFragment rule_src(os.str(), true);
+      Tree2StringGrammarNode* cur = root.back().get();
+      for (auto sym : rule_src)
+        cur = &cur->next[sym];
+      TRulePtr rule(new TRule(rhse, rhsf, lhs));
+      rule->ComputeArity();
+      rule->scores_.set_value(kFID, 1.0);
+      cur->rules.push_back(rule);
+    }
+  }
+
+  void RemoveGrammars() {
+    assert(remove_grammars < root.size());
+    root.resize(root.size() - remove_grammars);
+  }
+
   bool Translate(const string& input,
                  SentenceMetadata* smeta,
                  const vector<double>& weights,
                  Hypergraph* minus_lm_forest) {
+    remove_grammars = 0;
     cdec::TreeFragment input_tree(input, false);
+    if (add_pass_through_rules) CreatePassThroughRules(input_tree);
     Hypergraph hg;
     hg.ReserveNodes(input_tree.nodes.size());
     vector<int> tree2hg(input_tree.nodes.size() + 1, -1);
@@ -235,6 +281,7 @@ void Tree2StringTranslator::ProcessMarkupHintsImpl(const map<string, string>& kv
 }
 
 void Tree2StringTranslator::SentenceCompleteImpl() {
+  pimpl_->RemoveGrammars();
 }
 
 std::string Tree2StringTranslator::GetDecoderType() const {
-- 
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