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/***********************************************************************
Moses - statistical machine translation system
Copyright (C) 2006-2011 University of Edinburgh
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
***********************************************************************/
#pragma once
#ifndef EXTRACT_GHKM_NODE_H_
#define EXTRACT_GHKM_NODE_H_
#include <cassert>
#include <iterator>
#include <string>
#include <vector>
#include "Span.h"
namespace MosesTraining
{
namespace Syntax
{
namespace GHKM
{
class Subgraph;
enum NodeType { SOURCE, TARGET, TREE };
class Node
{
public:
Node(const std::string &label, NodeType type)
: m_label(label)
, m_type(type)
, m_pcfgScore(0.0f) {}
~Node();
const std::string &GetLabel() const {
return m_label;
}
NodeType GetType() const {
return m_type;
}
const std::vector<Node*> &GetChildren() const {
return m_children;
}
const std::vector<Node*> &GetParents() const {
return m_parents;
}
float GetPcfgScore() const {
return m_pcfgScore;
}
const Span &GetSpan() const {
return m_span;
}
const Span &GetComplementSpan() const {
return m_complementSpan;
}
const std::vector<const Subgraph*> &GetRules() const {
return m_rules;
}
void SetChildren(const std::vector<Node*> &c) {
m_children = c;
}
void SetParents(const std::vector<Node*> &p) {
m_parents = p;
}
void SetPcfgScore(float s) {
m_pcfgScore = s;
}
void SetSpan(const Span &s) {
m_span = s;
}
void SetComplementSpan(const Span &cs) {
m_complementSpan = cs;
}
void AddChild(Node *c) {
m_children.push_back(c);
}
void AddParent(Node *p) {
m_parents.push_back(p);
}
void AddRule(const Subgraph *s) {
m_rules.push_back(s);
}
bool IsSink() const {
return m_children.empty();
}
bool IsPreterminal() const;
void PropagateIndex(int);
std::vector<std::string> GetTargetWords() const;
// Gets the path from this node's parent to the root. This node is
// required to be part of the original parse tree (i.e. not a source word,
// which can have multiple parents).
template<typename OutputIterator>
void GetTreeAncestors(OutputIterator result, bool includeSelf=false);
// Returns the lowest common ancestor given a sequence of nodes belonging to
// the target tree.
template<typename InputIterator>
static Node *LowestCommonAncestor(InputIterator first, InputIterator last);
private:
// Disallow copying
Node(const Node &);
Node &operator=(const Node &);
void GetTargetWords(std::vector<std::string> &) const;
std::string m_label;
NodeType m_type;
std::vector<Node*> m_children;
std::vector<Node*> m_parents;
float m_pcfgScore;
Span m_span;
Span m_complementSpan;
std::vector<const Subgraph*> m_rules;
};
template<typename OutputIterator>
void Node::GetTreeAncestors(OutputIterator result, bool includeSelf)
{
// This function assumes the node is part of the parse tree.
assert(m_type == TARGET || m_type == TREE);
if (includeSelf) {
*result++ = this;
}
Node *ancestor = !(m_parents.empty()) ? m_parents[0] : 0;
while (ancestor != 0) {
*result++ = ancestor;
ancestor = !(ancestor->m_parents.empty()) ? ancestor->m_parents[0] : 0;
}
}
template<typename InputIterator>
Node *Node::LowestCommonAncestor(InputIterator first, InputIterator last)
{
// Check for an empty sequence.
if (first == last) {
return 0;
}
// Check for the case that the sequence contains only one distinct node.
// Also check that every node belongs to the target tree.
InputIterator p = first;
Node *lca = *p++;
for (; p != last; ++p) {
Node *node = *p;
assert(node->m_type != SOURCE);
if (node != lca) {
lca = 0;
}
}
if (lca) {
return lca;
}
// Now construct an ancestor path for each node, from itself to the root.
size_t minPathLength = 0;
std::vector<std::vector<Node *> > paths;
for (p = first; p != last; ++p) {
paths.resize(paths.size()+1);
(*p)->GetTreeAncestors(std::back_inserter(paths.back()), true);
size_t pathLength = paths.back().size();
assert(pathLength > 0);
if (paths.size() == 1 || pathLength < minPathLength) {
minPathLength = pathLength;
}
}
// Search for the start of the longest common suffix by working forward from
// the the earliest possible starting point to the root.
for (size_t i = 0; i < minPathLength; ++i) {
bool match = true;
for (size_t j = 0; j < paths.size(); ++j) {
size_t index = paths[j].size() - minPathLength + i;
assert(index >= 0);
assert(index < paths[j].size());
if (j == 0) {
lca = paths[j][index];
assert(lca);
} else if (lca != paths[j][index]) {
match = false;
break;
}
}
if (match) {
return lca;
}
}
// A lowest common ancestor should have been found.
assert(false);
return 0;
}
} // namespace GHKM
} // namespace Syntax
} // namespace MosesTraining
#endif
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