void AlignmentGraph::AttachUnalignedSourceWords()
{
// Find the unaligned source words (if any).
std::set<int> unaligned;
for (int i = 0; i < m_sourceNodes.size(); ++i) {
const Node &sourceNode = (*m_sourceNodes[i]);
if (sourceNode.GetParents().empty()) {
unaligned.insert(i);
}
}
// Determine the attachment point for each one and attach it.
for (std::set<int>::iterator p = unaligned.begin();
p != unaligned.end(); ++p) {
int index = *p;
Node *attachmentPoint = DetermineAttachmentPoint(index);
Node *sourceNode = m_sourceNodes[index];
attachmentPoint->AddChild(sourceNode);
sourceNode->AddParent(attachmentPoint);
}
}
Node *AlignmentGraph::CopyParseTree(const ParseTree *root)
{
NodeType nodeType = (root->IsLeaf()) ? TARGET : TREE;
std::auto_ptr<Node> n(new Node(root->GetLabel(), nodeType));
const std::vector<ParseTree *> &children = root->GetChildren();
std::vector<Node *> childNodes;
childNodes.reserve(children.size());
for (std::vector<ParseTree *>::const_iterator p(children.begin());
p != children.end(); ++p) {
Node *child = CopyParseTree(*p);
child->AddParent(n.get());
childNodes.push_back(child);
}
n->SetChildren(childNodes);
Node *p = n.release();
m_targetNodes.push_back(p);
return p;
}
AlignmentGraph::AlignmentGraph(const ParseTree *t,
const std::vector<std::string> &s,
const Alignment &a)
{
// Copy the parse tree nodes and add them to m_targetNodes.
m_root = CopyParseTree(t);
// Create a node for each source word.
m_sourceNodes.reserve(s.size());
for (std::vector<std::string>::const_iterator p(s.begin());
p != s.end(); ++p) {
m_sourceNodes.push_back(new Node(*p, SOURCE));
}
// Connect source nodes to parse tree leaves according to the given word
// alignment.
std::vector<Node *> targetTreeLeaves;
GetTargetTreeLeaves(m_root, targetTreeLeaves);
for (Alignment::const_iterator p(a.begin()); p != a.end(); ++p) {
Node *src = m_sourceNodes[p->first];
Node *tgt = targetTreeLeaves[p->second];
src->AddParent(tgt);
tgt->AddChild(src);
}
// Attach unaligned source words (if any).
AttachUnalignedSourceWords();
// Populate node spans.
std::vector<Node *>::const_iterator p(m_sourceNodes.begin());
for (int i = 0; p != m_sourceNodes.end(); ++p, ++i) {
(*p)->PropagateIndex(i);
}
// Calculate complement spans.
CalcComplementSpans(m_root);
}
