summaryrefslogtreecommitdiff
path: root/decoder/tree2string_translator.cc
blob: 29caaf8f83c91411fc6b7bf864c08f8166a05869 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
#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";
}