void HwcmScorer::extractHeadWordChain(TreePointer tree, vector<string> & history, vector<map<string, int> > & hwc) {
if (tree->GetLength() > 0) {
string head = getHead(tree);
if (head.empty()) {
for (std::vector<TreePointer>::const_iterator it = tree->GetChildren().begin(); it != tree->GetChildren().end(); ++it) {
extractHeadWordChain(*it, history, hwc);
}
}
else {
vector<string> new_history(kHwcmOrder);
new_history[0] = head;
hwc[0][head]++;
for (size_t hist_idx = 0; hist_idx < kHwcmOrder-1; hist_idx++) {
if (!history[hist_idx].empty()) {
string chain = history[hist_idx] + " " + head;
hwc[hist_idx+1][chain]++;
if (hist_idx+2 < kHwcmOrder) {
new_history[hist_idx+1] = chain;
}
}
}
for (std::vector<TreePointer>::const_iterator it = tree->GetChildren().begin(); it != tree->GetChildren().end(); ++it) {
extractHeadWordChain(*it, new_history, hwc);
}
}
}
}
string HwcmScorer::getHead(TreePointer tree) {
// assumption (only true for dependency parse: each constituent has a preterminal label, and corresponding terminal is head)
// if constituent has multiple preterminals, first one is picked; if it has no preterminals, empty string is returned
for (std::vector<TreePointer>::const_iterator it = tree->GetChildren().begin(); it != tree->GetChildren().end(); ++it)
{
TreePointer child = *it;
if (child->GetLength() == 1 && child->GetChildren()[0]->IsTerminal()) {
return child->GetChildren()[0]->GetLabel();
}
}
return "";
}
FFState* TreeStructureFeature::EvaluateWhenApplied(const ChartHypothesis& cur_hypo
, int featureID /* used to index the state in the previous hypotheses */
, ScoreComponentCollection* accumulator) const
{
if (const PhraseProperty *property = cur_hypo.GetCurrTargetPhrase().GetProperty("Tree")) {
const std::string *tree = property->GetValueString();
TreePointer mytree (boost::make_shared<InternalTree>(*tree));
//get subtrees (in target order)
std::vector<TreePointer> previous_trees;
for (size_t pos = 0; pos < cur_hypo.GetCurrTargetPhrase().GetSize(); ++pos) {
const Word &word = cur_hypo.GetCurrTargetPhrase().GetWord(pos);
if (word.IsNonTerminal()) {
size_t nonTermInd = cur_hypo.GetCurrTargetPhrase().GetAlignNonTerm().GetNonTermIndexMap()[pos];
const ChartHypothesis *prevHypo = cur_hypo.GetPrevHypo(nonTermInd);
const TreeState* prev = dynamic_cast<const TreeState*>(prevHypo->GetFFState(featureID));
const TreePointer prev_tree = prev->GetTree();
previous_trees.push_back(prev_tree);
}
}
if (m_constraints) {
m_constraints->SyntacticRules(mytree, previous_trees, this, accumulator);
}
mytree->Combine(previous_trees);
bool full_sentence = (mytree->GetChildren().back()->GetLabel() == m_send || (mytree->GetChildren().back()->GetLabel() == m_send_nt && mytree->GetChildren().back()->GetChildren().back()->GetLabel() == m_send));
if (m_binarized && full_sentence) {
mytree->Unbinarize();
}
return new TreeState(mytree);
} else {
UTIL_THROW2("Error: TreeStructureFeature active, but no internal tree structure found");
}
}
// define NT labels (ints) that are mapped from strings for quicker comparison.
void TreeStructureFeature::AddNTLabels(TreePointer root) const {
std::string label = root->GetLabel();
if (root->IsTerminal()) {
return;
}
std::map<std::string, NTLabel>::const_iterator it = m_labelset->string_to_label.find(label);
if (it != m_labelset->string_to_label.end()) {
root->SetNTLabel(it->second);
}
std::vector<TreePointer> children = root->GetChildren();
for (std::vector<TreePointer>::const_iterator it2 = children.begin(); it2 != children.end(); ++it2) {
AddNTLabels(*it2);
}
}
