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#include "phrasebased_translator.h"
#include <queue>
#include <iostream>
#include <tr1/unordered_map>
#include <tr1/unordered_set>
#include <boost/tuple/tuple.hpp>
#include <boost/functional/hash.hpp>
#include "sentence_metadata.h"
#include "tdict.h"
#include "hg.h"
#include "filelib.h"
#include "lattice.h"
#include "phrasetable_fst.h"
#include "array2d.h"
using namespace std;
using namespace std::tr1;
using namespace boost::tuples;
struct Coverage : public vector<bool> {
explicit Coverage(int n, bool v = false) : vector<bool>(n, v), first_gap() {}
void Cover(int i, int j) {
vector<bool>::iterator it = this->begin() + i;
vector<bool>::iterator end = this->begin() + j;
while (it != end)
*it++ = true;
if (first_gap == i) {
first_gap = j;
it = end;
while (*it && it != this->end()) {
++it;
++first_gap;
}
}
}
bool Collides(int i, int j) const {
vector<bool>::const_iterator it = this->begin() + i;
vector<bool>::const_iterator end = this->begin() + j;
while (it != end)
if (*it++) return true;
return false;
}
int GetFirstGap() const { return first_gap; }
private:
int first_gap;
};
struct CoverageHash {
size_t operator()(const Coverage& cov) const {
return hasher_(static_cast<const vector<bool>&>(cov));
}
private:
boost::hash<vector<bool> > hasher_;
};
ostream& operator<<(ostream& os, const Coverage& cov) {
os << '[';
for (int i = 0; i < cov.size(); ++i)
os << (cov[i] ? '*' : '.');
return os << " gap=" << cov.GetFirstGap() << ']';
}
typedef unordered_map<Coverage, int, CoverageHash> CoverageNodeMap;
typedef unordered_set<Coverage, CoverageHash> UniqueCoverageSet;
struct PhraseBasedTranslatorImpl {
PhraseBasedTranslatorImpl(const boost::program_options::variables_map& conf) :
add_pass_through_rules(conf.count("add_pass_through_rules")),
max_distortion(conf["pb_max_distortion"].as<int>()),
kSOURCE_RULE(new TRule("[X] ||| [X,1] ||| [X,1]", true)),
kCONCAT_RULE(new TRule("[X] ||| [X,1] [X,2] ||| [X,1] [X,2]", true)),
kNT_TYPE(TD::Convert("X") * -1) {
assert(max_distortion >= 0);
vector<string> gfiles = conf["grammar"].as<vector<string> >();
assert(gfiles.size() == 1);
cerr << "Reading phrasetable from " << gfiles.front() << endl;
ReadFile in(gfiles.front());
fst.reset(LoadTextPhrasetable(in.stream()));
}
struct State {
State(const Coverage& c, int _i, int _j, const FSTNode* q) :
coverage(c), i(_i), j(_j), fst(q) {}
Coverage coverage;
int i;
int j;
const FSTNode* fst;
};
// we keep track of unique coverages that have been extended since it's
// possible to "extend" the same coverage twice, e.g. translate "a b c"
// with phrases "a" "b" "a b" and "c". There are two ways to cover "a b"
void EnqueuePossibleContinuations(const Coverage& coverage, queue<State>* q, UniqueCoverageSet* ucs) {
if (ucs->insert(coverage).second) {
const int gap = coverage.GetFirstGap();
const int end = min(static_cast<int>(coverage.size()), gap + max_distortion + 1);
for (int i = gap; i < end; ++i)
if (!coverage[i]) q->push(State(coverage, i, i, fst.get()));
}
}
bool Translate(const std::string& input,
SentenceMetadata* smeta,
const std::vector<double>& weights,
Hypergraph* minus_lm_forest) {
Lattice lattice;
LatticeTools::ConvertTextOrPLF(input, &lattice);
smeta->SetSourceLength(lattice.size());
size_t est_nodes = lattice.size() * lattice.size() * (1 << max_distortion);
minus_lm_forest->ReserveNodes(est_nodes, est_nodes * 100);
if (add_pass_through_rules) {
SparseVector<double> feats;
feats.set_value(FD::Convert("PassThrough"), 1);
for (int i = 0; i < lattice.size(); ++i) {
const vector<LatticeArc>& arcs = lattice[i];
for (int j = 0; j < arcs.size(); ++j) {
fst->AddPassThroughTranslation(arcs[j].label, feats);
// TODO handle lattice edge features
}
}
}
CoverageNodeMap c;
queue<State> q;
UniqueCoverageSet ucs;
const Coverage empty_cov(lattice.size(), false);
const Coverage goal_cov(lattice.size(), true);
EnqueuePossibleContinuations(empty_cov, &q, &ucs);
c[empty_cov] = 0; // have to handle the left edge specially
while(!q.empty()) {
const State s = q.front();
q.pop();
// cerr << "(" << s.i << "," << s.j << " ptr=" << s.fst << ") cov=" << s.coverage << endl;
const vector<LatticeArc>& arcs = lattice[s.j];
if (s.fst->HasData()) {
Coverage new_cov = s.coverage;
new_cov.Cover(s.i, s.j);
EnqueuePossibleContinuations(new_cov, &q, &ucs);
const vector<TRulePtr>& phrases = s.fst->GetTranslations()->GetRules();
const int phrase_head_index = minus_lm_forest->AddNode(kNT_TYPE)->id_;
for (int i = 0; i < phrases.size(); ++i) {
Hypergraph::Edge* edge = minus_lm_forest->AddEdge(phrases[i], Hypergraph::TailNodeVector());
edge->feature_values_ = edge->rule_->scores_;
minus_lm_forest->ConnectEdgeToHeadNode(edge->id_, phrase_head_index);
}
CoverageNodeMap::iterator cit = c.find(s.coverage);
assert(cit != c.end());
const int tail_node_plus1 = cit->second;
if (tail_node_plus1 == 0) { // left edge
c[new_cov] = phrase_head_index + 1;
} else { // not left edge
int& head_node_plus1 = c[new_cov];
if (!head_node_plus1)
head_node_plus1 = minus_lm_forest->AddNode(kNT_TYPE)->id_ + 1;
Hypergraph::TailNodeVector tail(2, tail_node_plus1 - 1);
tail[1] = phrase_head_index;
const int concat_edge = minus_lm_forest->AddEdge(kCONCAT_RULE, tail)->id_;
minus_lm_forest->ConnectEdgeToHeadNode(concat_edge, head_node_plus1 - 1);
}
}
if (s.j == lattice.size()) continue;
for (int l = 0; l < arcs.size(); ++l) {
const LatticeArc& arc = arcs[l];
const FSTNode* next_fst_state = s.fst->Extend(arc.label);
const int next_j = s.j + arc.dist2next;
if (next_fst_state &&
!s.coverage.Collides(s.i, next_j)) {
q.push(State(s.coverage, s.i, next_j, next_fst_state));
}
}
}
if (add_pass_through_rules)
fst->ClearPassThroughTranslations();
int pregoal_plus1 = c[goal_cov];
if (pregoal_plus1 > 0) {
TRulePtr kGOAL_RULE(new TRule("[Goal] ||| [X,1] ||| [X,1]"));
int goal = minus_lm_forest->AddNode(TD::Convert("Goal") * -1)->id_;
int gedge = minus_lm_forest->AddEdge(kGOAL_RULE, Hypergraph::TailNodeVector(1, pregoal_plus1 - 1))->id_;
minus_lm_forest->ConnectEdgeToHeadNode(gedge, goal);
// they are almost topo, but not quite always
minus_lm_forest->TopologicallySortNodesAndEdges(goal);
minus_lm_forest->Reweight(weights);
return true;
} else {
return false; // composition failed
}
}
const bool add_pass_through_rules;
const int max_distortion;
TRulePtr kSOURCE_RULE;
const TRulePtr kCONCAT_RULE;
const WordID kNT_TYPE;
boost::shared_ptr<FSTNode> fst;
};
PhraseBasedTranslator::PhraseBasedTranslator(const boost::program_options::variables_map& conf) :
pimpl_(new PhraseBasedTranslatorImpl(conf)) {}
bool PhraseBasedTranslator::TranslateImpl(const std::string& input,
SentenceMetadata* smeta,
const std::vector<double>& weights,
Hypergraph* minus_lm_forest) {
return pimpl_->Translate(input, smeta, weights, minus_lm_forest);
}
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