From 8015250ddd3983320b6e54ca7f1914a465bc8a59 Mon Sep 17 00:00:00 2001
From: Chris Dyer <redpony@gmail.com>
Date: Fri, 14 Feb 2014 22:30:05 -0500
Subject: fix unary handling in scfg parser

---
 decoder/bottom_up_parser.cc | 80 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 69 insertions(+), 11 deletions(-)

(limited to 'decoder')

diff --git a/decoder/bottom_up_parser.cc b/decoder/bottom_up_parser.cc
index 606b8d7e..8738c8f1 100644
--- a/decoder/bottom_up_parser.cc
+++ b/decoder/bottom_up_parser.cc
@@ -45,6 +45,7 @@ class PassiveChart {
                  const float lattice_cost);
 
   void ApplyUnaryRules(const int i, const int j);
+  void TopoSortUnaries();
 
   const vector<GrammarPtr>& grammars_;
   const Lattice& input_;
@@ -57,6 +58,7 @@ class PassiveChart {
   TRulePtr goal_rule_;
   int goal_idx_;             // index of goal node, if found
   const int lc_fid_;
+  vector<TRulePtr> unaries_; // topologically sorted list of unary rules from all grammars
 
   static WordID kGOAL;       // [Goal]
 };
@@ -159,21 +161,78 @@ PassiveChart::PassiveChart(const string& goal,
     goal_cat_(TD::Convert(goal) * -1),
     goal_rule_(new TRule("[Goal] ||| [" + goal + ",1] ||| [" + goal + ",1]")),
     goal_idx_(-1),
-    lc_fid_(FD::Convert("LatticeCost")) {
+    lc_fid_(FD::Convert("LatticeCost")),
+    unaries_() {
   act_chart_.resize(grammars_.size());
-  for (unsigned i = 0; i < grammars_.size(); ++i)
+  for (unsigned i = 0; i < grammars_.size(); ++i) {
     act_chart_[i] = new ActiveChart(forest, *this);
+    const vector<TRulePtr>& u = grammars_[i]->GetAllUnaryRules();
+    for (unsigned j = 0; j < u.size(); ++j)
+      unaries_.push_back(u[j]);
+  }
+  TopoSortUnaries();
   if (!kGOAL) kGOAL = TD::Convert("Goal") * -1;
   if (!SILENT) cerr << "  Goal category: [" << goal << ']' << endl;
 }
 
+static bool TopoSortVisit(int node, vector<TRulePtr>& u, const map<int, vector<TRulePtr> >& g, map<int, int>& mark) {
+  if (mark[node] == 1) {
+    cerr << "[ERROR] Unary rule cycle detected involving [" << TD::Convert(-node) << "]\n";
+    return false; // cycle detected
+  } else if (mark[node] == 2) {
+    return true; // already been 
+  }
+  mark[node] = 1;
+  const map<int, vector<TRulePtr> >::const_iterator nit = g.find(node);
+  if (nit != g.end()) {
+    const vector<TRulePtr>& edges = nit->second;
+    vector<bool> okay(edges.size(), true);
+    for (unsigned i = 0; i < edges.size(); ++i) {
+      okay[i] = TopoSortVisit(edges[i]->lhs_, u, g, mark);
+      if (!okay[i]) {
+        cerr << "[ERROR] Unary rule cycle detected, removing: " << edges[i]->AsString() << endl;
+      }
+   }
+    for (unsigned i = 0; i < edges.size(); ++i) {
+      if (okay[i]) u.push_back(edges[i]);
+      //if (okay[i]) cerr << "UNARY: " << edges[i]->AsString() << endl;
+    }
+  }
+  mark[node] = 2;
+  return true;
+}
+
+void PassiveChart::TopoSortUnaries() {
+  vector<TRulePtr> u(unaries_.size()); u.clear();
+  map<int, vector<TRulePtr> > g;
+  map<int, int> mark;
+  //cerr << "GOAL=" << TD::Convert(-goal_cat_) << endl;
+  mark[goal_cat_] = 2;
+  for (unsigned i = 0; i < unaries_.size(); ++i) {
+    //cerr << "Adding: " << unaries_[i]->AsString() << endl;
+    g[unaries_[i]->f()[0]].push_back(unaries_[i]);
+  }
+    //m[unaries_[i]->lhs_].push_back(unaries_[i]);
+  for (map<int, vector<TRulePtr> >::iterator it = g.begin(); it != g.end(); ++it) {
+    //cerr << "PROC: " << TD::Convert(-it->first) << endl;
+    if (mark[it->first] > 0) {
+      //cerr << "Already saw [" << TD::Convert(-it->first) << "]\n";
+    } else {
+      TopoSortVisit(it->first, u, g, mark);
+    }
+  }
+  unaries_.clear();
+  for (int i = u.size() - 1; i >= 0; --i)
+    unaries_.push_back(u[i]);
+}
+
 void PassiveChart::ApplyRule(const int i,
                              const int j,
                              const TRulePtr& r,
                              const Hypergraph::TailNodeVector& ant_nodes,
                              const float lattice_cost) {
   Hypergraph::Edge* new_edge = forest_->AddEdge(r, ant_nodes);
-  //cerr << i << " " << j << ": APPLYING RULE: " << r->AsString() << endl;
+  // cerr << i << " " << j << ": APPLYING RULE: " << r->AsString() << endl;
   new_edge->prev_i_ = r->prev_i;
   new_edge->prev_j_ = r->prev_j;
   new_edge->i_ = i;
@@ -215,15 +274,14 @@ void PassiveChart::ApplyRules(const int i,
 
 void PassiveChart::ApplyUnaryRules(const int i, const int j) {
   const vector<int>& nodes = chart_(i,j);  // reference is important!
-  for (unsigned gi = 0; gi < grammars_.size(); ++gi) {
-    if (!grammars_[gi]->HasRuleForSpan(i,j,input_.Distance(i,j))) continue;
-    for (unsigned di = 0; di < nodes.size(); ++di) {
-      const WordID& cat = forest_->nodes_[nodes[di]].cat_;
-      const vector<TRulePtr>& unaries = grammars_[gi]->GetUnaryRulesForRHS(cat);
-      for (unsigned ri = 0; ri < unaries.size(); ++ri) {
-        // cerr << "At (" << i << "," << j << "): applying " << unaries[ri]->AsString() << endl;
+  for (unsigned di = 0; di < nodes.size(); ++di) {
+    const WordID& cat = forest_->nodes_[nodes[di]].cat_;
+    for (unsigned ri = 0; ri < unaries_.size(); ++ri) {
+      //cerr << "At (" << i << "," << j << "): applying " << unaries_[ri]->AsString() << endl;
+      if (unaries_[ri]->f()[0] == cat) {
+        //cerr << "  --MATCH\n";
         const Hypergraph::TailNodeVector ant(1, nodes[di]);
-        ApplyRule(i, j, unaries[ri], ant, 0);  // may update nodes
+        ApplyRule(i, j, unaries_[ri], ant, 0);  // may update nodes
       }
     }
   }
-- 
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