diff options
| -rw-r--r-- | decoder/tree2string_translator.cc | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/decoder/tree2string_translator.cc b/decoder/tree2string_translator.cc index d61b9aba..c9c91a37 100644 --- a/decoder/tree2string_translator.cc +++ b/decoder/tree2string_translator.cc @@ -29,6 +29,7 @@ static void ReadTree2StringGrammar(istream* in, Tree2StringGrammarNode* root, bo int lc = 0; while(getline(*in, line)) { ++lc; + if (line.size() == 0 || line[0] == '#') continue; std::vector<StringPiece> fields = TokenizeMultisep(line, " ||| "); if (has_multiple_states && fields.size() != 4) { cerr << "Expected 4 fields in rule file but line " << lc << " is:\n" << line << endl; @@ -178,6 +179,32 @@ struct Tree2StringTranslatorImpl { ReadTree2StringGrammar(rf.stream(), root.back().get(), has_multiple_states); } + // src must be fully abstract + bool DoesAbstractPassThroughRuleExist(unsigned state, const cdec::TreeFragment& src) const { + unsigned len = root.size(); + if (len <= 1) return false; + --len; + for (unsigned i = 0; i < len; ++i) { + const Tree2StringGrammarNode* cur = &*root[i]; + auto it = cur->next.find(state); + if (it == cur->next.end()) continue; + cur = &it->second; + bool failed = false; + vector<int> trg; + for (auto sym : src) { + it = cur->next.find(sym); + if (it == cur->next.end()) { failed = true; break; } + if (cdec::IsFrontier(sym)) trg.push_back(-trg.size()); + cur = &it->second; + } + if (failed) continue; + // TODO check for destination states in t2t + for (auto r : cur->rules) + if (r->e_ == trg) return true; + } + return false; + } + void CreatePassThroughRules(const cdec::TreeFragment& tree) { static const int kFIDlex = FD::Convert("PassThrough_Lexical"); static const int kFIDabs = FD::Convert("PassThrough_Abstract"); @@ -231,6 +258,9 @@ struct Tree2StringTranslatorImpl { Tree2StringGrammarNode* cur = root.back().get(); // do we need all transducer states here??? a list??? no pass through rules??? unsigned transducer_state = 0; + const bool abstract_rule = (has_nt && !has_lex); + // the following reduces ambiguity quite a lot + if (abstract_rule && DoesAbstractPassThroughRuleExist(transducer_state, rule_src)) continue; cur = &cur->next[transducer_state]; for (auto sym : rule_src) cur = &cur->next[sym]; |