path: root/decoder/tree2string_translator.cc

#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <unordered_set>
#include <boost/shared_ptr.hpp>
#include <boost/functional/hash.hpp>
#include "tree_fragment.h"
#include "translator.h"
#include "hg.h"
#include "sentence_metadata.h"
#include "filelib.h"
#include "stringlib.h"
#include "tdict.h"
#include "verbose.h"

using namespace std;

struct Tree2StringGrammarNode {
  map<unsigned, Tree2StringGrammarNode> next;
  vector<TRulePtr> rules;
};

void ReadTree2StringGrammar(istream* in, Tree2StringGrammarNode* root) {
  string line;
  while(getline(*in, line)) {
    size_t pos = line.find("|||");
    assert(pos != string::npos);
    assert(pos > 3);
    unsigned xc = 0;
    while (line[pos - 1] == ' ') { --pos; xc++; }
    cdec::TreeFragment rule_src(line.substr(0, pos), true);
    // TODO transducer_state should (optionally?) be read from input
    const unsigned transducer_state = 0;
    Tree2StringGrammarNode* cur = &root->next[transducer_state];
    ostringstream os;
    int lhs = -(rule_src.root & cdec::ALL_MASK);
    // build source RHS for SCFG projection
    // TODO - this is buggy - it will generate a well-formed SCFG rule
    // so it will not generate source strings correctly
    // it will, however, generate target translations appropriately
    vector<int> frhs;
    for (auto sym : rule_src) {
      //cerr << TD::Convert(sym & cdec::ALL_MASK) << endl;
      cur = &cur->next[sym];
      if (cdec::IsFrontier(sym)) {  // frontier symbols -> variables
        int nt = (sym & cdec::ALL_MASK);
        frhs.push_back(-nt);
      } else if (cdec::IsTerminal(sym)) {
        frhs.push_back(sym);
      }
    }
    os << '[' << TD::Convert(-lhs) << "] |||";
    for (auto x : frhs) {
      os << ' ';
      if (x < 0)
        os << '[' << TD::Convert(-x) << ']';
      else
        os << TD::Convert(x);
    }
    pos += 3 + xc;
    while(line[pos] == ' ') { ++pos; }
    os << " ||| " << line.substr(pos);
    TRulePtr rule(new TRule(os.str()));
    // TODO the transducer_state you end up in after using this rule (for each NT)
    // needs to be read and encoded somehow in the rule (for use XXX)
    cur->rules.push_back(rule);
    //cerr << "RULE: " << rule->AsString() << "\n\n";
  }
}

// represents where in an input parse tree the transducer must continue
// and what state it is in
struct TransducerState {
  TransducerState() : input_node_idx(), transducer_state() {}
  TransducerState(unsigned n, unsigned q) : input_node_idx(n), transducer_state(q) {}
  bool operator==(const TransducerState& o) const {
    return input_node_idx == o.input_node_idx &&
           transducer_state == o.transducer_state;
  }
  unsigned input_node_idx;
  unsigned transducer_state;
};

// represents the state of the composition algorithm
struct ParserState {
  ParserState() : in_iter(), node() {}
  cdec::TreeFragment::iterator in_iter;
  ParserState(const cdec::TreeFragment::iterator& it, unsigned q, Tree2StringGrammarNode* n) :
      in_iter(it),
      task(it.node_idx(), q),
      node(n) {}
  ParserState(const cdec::TreeFragment::iterator& it, Tree2StringGrammarNode* n, const ParserState& p) :
      in_iter(it),
      future_work(p.future_work),
      task(p.task),
      node(n) {}
  bool operator==(const ParserState& o) const {
    return node == o.node && task == o.task &&
           future_work == o.future_work && in_iter == o.in_iter;
  }
  vector<TransducerState> future_work;
  TransducerState task; // subtree root where and in what state did the transducer start?
  Tree2StringGrammarNode* node; // pointer into grammar trie
};

namespace std {
  template<>
  struct hash<TransducerState> {
    size_t operator()(const TransducerState& q) const {
      size_t h = boost::hash_value(q.transducer_state);
      boost::hash_combine(h, boost::hash_value(q.input_node_idx));
      return h;
    }
  };
  template<>
  struct hash<ParserState> {
    size_t operator()(const ParserState& s) const {
      size_t h = boost::hash_value(s.node);
      for (auto& w : s.future_work)
        boost::hash_combine(h, hash<TransducerState>()(w));
      boost::hash_combine(h, hash<TransducerState>()(s.task));
      // TODO hash with iterator
      return h;
    }
  }; 
};

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")) {
      const vector<string> gf = conf["grammar"].as<vector<string>>();
      root.resize(gf.size());
      unsigned gc = 0;
      for (auto& f : gf) {
        ReadFile rf(f);
        root[gc].reset(new Tree2StringGrammarNode);
        ReadTree2StringGrammar(rf.stream(), &*root[gc++]);
      }
    }
  }

  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();
      // do we need all transducer states here??? a list??? no pass through rules???
      unsigned transducer_state = 0;
      cur = &cur->next[transducer_state];
      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());
    unordered_map<TransducerState, unsigned> x2hg(input_tree.nodes.size() * 5);
    queue<ParserState> q;
    unordered_set<ParserState> unique;  // only create items one time
    for (auto& g : root) {
      unsigned q_0 = 0; // TODO initialize q_0 properly once multi-state transducers are supported
      auto rit = g->next.find(q_0);
      if (rit != g->next.end()) { // does this g have this transducer state?
        q.push(ParserState(input_tree.begin(), q_0, &rit->second));
        unique.insert(q.back());
      }
    }
    if (q.size() == 0) return false;
    const TransducerState tree_top = q.front().task;
    while(!q.empty()) {
      ParserState& s = q.front();

      if (s.in_iter.at_end()) { // completed a traversal of a subtree
        //cerr << "I traversed a subtree of the input rooted at node=" << s.input_node_idx << " sym=" << 
        //   TD::Convert(input_tree.nodes[s.input_node_idx].lhs & cdec::ALL_MASK) << endl;
        if (s.node->rules.size()) {
          auto it = x2hg.find(s.task);
          if (it == x2hg.end()) {
            // TODO create composite state symbol that encodes transducer state type?
            HG::Node* new_node = hg.AddNode(-(input_tree.nodes[s.task.input_node_idx].lhs & cdec::ALL_MASK));
            new_node->node_hash = std::hash<TransducerState>()(s.task);
            it = x2hg.insert(make_pair(s.task, new_node->id_)).first;
          }
          const unsigned node_id = it->second;
          TailNodeVector tail;
          for (const auto& n : s.future_work) {
            auto it = x2hg.find(n);
            if (it == x2hg.end()) {
              // TODO create composite state symbol that encodes transducer state type?
              HG::Node* new_node = hg.AddNode(-(input_tree.nodes[n.input_node_idx].lhs & cdec::ALL_MASK));
              new_node->node_hash = std::hash<TransducerState>()(n);
              it = x2hg.insert(make_pair(n, new_node->id_)).first;
            }
            tail.push_back(it->second);
          }
          for (auto& r : s.node->rules) {
            assert(tail.size() == r->Arity());
            HG::Edge* new_edge = hg.AddEdge(r, tail);
            new_edge->feature_values_ = r->GetFeatureValues();
            // TODO: set i and j
            hg.ConnectEdgeToHeadNode(new_edge, &hg.nodes_[node_id]);
          }
          for (const auto& n : s.future_work) {
            const auto it = input_tree.begin(n.input_node_idx); // start tree iterator at node n
            for (auto& g : root) {
              auto rit = g->next.find(n.transducer_state);
              if (rit != g->next.end()) { // does this g have this transducer state?
                const ParserState s(it, n.transducer_state, &rit->second);
                if (unique.insert(s).second) q.push(s);
              }
            }
          }
        } else {
          //cerr << "I can't build anything :(\n";
        }
      } else { // more input tree to match
        unsigned sym = *s.in_iter;
        if (cdec::IsLHS(sym)) {
          auto nit = s.node->next.find(sym);
          if (nit != s.node->next.end()) {
            //cerr << "MATCHED LHS: " << TD::Convert(sym & cdec::ALL_MASK) << endl;
            ParserState news(++s.in_iter, &nit->second, s);
            if (unique.insert(news).second) q.push(news);
          }
        } else if (cdec::IsRHS(sym)) {
          //cerr << "Attempting to match RHS: " << TD::Convert(sym & cdec::ALL_MASK) << endl;
          cdec::TreeFragment::iterator var = s.in_iter;
          var.truncate();
          auto nit1 = s.node->next.find(sym);
          auto nit2 = s.node->next.find(*var);
          if (nit2 != s.node->next.end()) {
            //cerr << "MATCHED VAR RHS: " << TD::Convert(sym & cdec::ALL_MASK) << endl;
            ++var;
            // TODO: find out from rule what the new target state is (the 0 in the next line)
            // if it is associated with the rule, we won't know until we match the whole input
            // so the 0 may be okay (if this is the case, which is probably the easiest thing,
            // then the state must be dealt with when the future work becomes real work)
            const TransducerState new_task(s.in_iter.child_node(), 0);
            ParserState new_s(var, &nit2->second, s);
            new_s.future_work.push_back(new_task);  // if this traversal of the input succeeds, future_work goes on the q
            if (unique.insert(new_s).second) q.push(new_s);
          }
          //else { cerr << "did not match [" << TD::Convert(sym & cdec::ALL_MASK) << "]\n"; }
          if (nit1 != s.node->next.end()) {
            //cerr << "MATCHED FULL RHS: " << TD::Convert(sym & cdec::ALL_MASK) << endl;
            const ParserState new_s(++s.in_iter, &nit1->second, s);
            if (unique.insert(new_s).second) q.push(new_s);
          }
          //else { cerr << "did not match " << TD::Convert(sym & cdec::ALL_MASK) << "\n"; }
        } else if (cdec::IsTerminal(sym)) {
          auto nit = s.node->next.find(sym);
          if (nit != s.node->next.end()) {
            //cerr << "MATCHED TERMINAL: " << TD::Convert(sym) << endl;
            const ParserState new_s(++s.in_iter, &nit->second, s);
            if (unique.insert(new_s).second) q.push(new_s);
          }
        } else {
          cerr << "This can never happen!\n"; abort();
        }
      }
      q.pop();
    }
    const auto goal_it = x2hg.find(tree_top);
    if (goal_it == x2hg.end()) return false;
    //cerr << "Goal node: " << goal << endl;
    hg.TopologicallySortNodesAndEdges(goal_it->second);
    hg.Reweight(weights);

    // there might be nodes that cannot be derived
    // the following takes care of them
    vector<bool> prune(hg.edges_.size(), false);
    hg.PruneEdges(prune, true);
    if (hg.edges_.size() == 0) return false;
    //hg.PrintGraphviz();
    minus_lm_forest->swap(hg);
    return true;
  }
};

Tree2StringTranslator::Tree2StringTranslator(const boost::program_options::variables_map& conf) :
  pimpl_(new Tree2StringTranslatorImpl(conf)) {}

bool Tree2StringTranslator::TranslateImpl(const string& input,
                               SentenceMetadata* smeta,
                               const vector<double>& weights,
                               Hypergraph* minus_lm_forest) {
  return pimpl_->Translate(input, smeta, weights, minus_lm_forest);
}

void Tree2StringTranslator::ProcessMarkupHintsImpl(const map<string, string>& kv) {
}

void Tree2StringTranslator::SentenceCompleteImpl() {
  pimpl_->RemoveGrammars();
}

std::string Tree2StringTranslator::GetDecoderType() const {
  return "tree2string";
}