internal_node::internal_node(const internal_node& other)
: base{other.category()}
{
other.each_child([&](const node* n)
{
children_.emplace_back(n->clone());
if (n == other.head_constituent())
head(children_.back().get());
});
}
std::unique_ptr<node> binarizer::operator()(const internal_node& in)
{
auto res = make_unique<internal_node>(in.category());
if (in.num_children() <= 2)
{
in.each_child([&](const node* child)
{
res->add_child(child->accept(*this));
if (child == in.head_constituent())
res->head(res->child(res->num_children() - 1));
});
return std::move(res);
}
auto bin_lbl = class_label{static_cast<std::string>(in.category()) + "*"};
// locate head node
auto head = in.head_constituent();
if (!head)
throw exception{"Head constituent not labeled"};
uint64_t head_idx = 0;
for (uint64_t idx = 0; idx < in.num_children(); ++idx)
{
if (in.child(idx) == in.head_constituent())
head_idx = idx;
}
// eat left nodes
auto curr = res.get();
for (uint64_t idx = 0; idx < head_idx; ++idx)
{
curr->add_child(in.child(idx)->accept(*this));
// special case: if the head is the very last node, just add the
// remaining child (the head) to the current node
if (idx + 1 == head_idx && head_idx == in.num_children() - 1)
{
curr->add_child(in.child(idx + 1)->accept(*this));
curr->head(curr->child(1));
break;
}
else
{
auto bin = make_unique<internal_node>(bin_lbl);
auto next = bin.get();
curr->add_child(std::move(bin));
curr->head(curr->child(1));
curr = next;
}
}
// eat right nodes
for (uint64_t ridx = in.num_children() - 1; ridx > head_idx; --ridx)
{
// if the head is the next node, just add it and the current child
if (head_idx + 1 == ridx)
{
curr->add_child(in.child(ridx - 1)->accept(*this));
curr->head(curr->child(0));
curr->add_child(in.child(ridx)->accept(*this));
break;
}
else
{
auto bin = make_unique<internal_node>(bin_lbl);
auto next = bin.get();
curr->add_child(std::move(bin));
curr->head(curr->child(0));
curr->add_child(in.child(ridx)->accept(*this));
curr = next;
}
}
lexicon_populator pop;
res->accept(pop);
return std::move(res);
}