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// See www.openfst.org for extensive documentation on this weighted
// finite-state transducer library.
#ifndef FST_SCRIPT_SHORTEST_DISTANCE_H_
#define FST_SCRIPT_SHORTEST_DISTANCE_H_
#include <tuple>
#include <vector>
#include <fst/queue.h>
#include <fst/shortest-distance.h>
#include <fst/script/fst-class.h>
#include <fst/script/prune.h>
#include <fst/script/script-impl.h>
#include <fst/script/weight-class.h>
namespace fst {
namespace script {
enum ArcFilterType {
ANY_ARC_FILTER,
EPSILON_ARC_FILTER,
INPUT_EPSILON_ARC_FILTER,
OUTPUT_EPSILON_ARC_FILTER
};
struct ShortestDistanceOptions {
const QueueType queue_type;
const ArcFilterType arc_filter_type;
const int64 source;
const float delta;
ShortestDistanceOptions(QueueType queue_type, ArcFilterType arc_filter_type,
int64 source, float delta)
: queue_type(queue_type),
arc_filter_type(arc_filter_type),
source(source),
delta(delta) {}
};
namespace internal {
// Code to implement switching on queue and arc filter types.
template <class Arc, class Queue, class ArcFilter>
struct QueueConstructor {
using Weight = typename Arc::Weight;
static Queue *Construct(const Fst<Arc> &, const std::vector<Weight> *) {
return new Queue();
}
};
// Specializations to support queues with different constructors.
template <class Arc, class ArcFilter>
struct QueueConstructor<Arc, AutoQueue<typename Arc::StateId>, ArcFilter> {
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
// template<class Arc, class ArcFilter>
static AutoQueue<StateId> *Construct(const Fst<Arc> &fst,
const std::vector<Weight> *distance) {
return new AutoQueue<StateId>(fst, distance, ArcFilter());
}
};
template <class Arc, class ArcFilter>
struct QueueConstructor<
Arc, NaturalShortestFirstQueue<typename Arc::StateId, typename Arc::Weight>,
ArcFilter> {
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
static NaturalShortestFirstQueue<StateId, Weight> *Construct(
const Fst<Arc> &, const std::vector<Weight> *distance) {
return new NaturalShortestFirstQueue<StateId, Weight>(*distance);
}
};
template <class Arc, class ArcFilter>
struct QueueConstructor<Arc, TopOrderQueue<typename Arc::StateId>, ArcFilter> {
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
static TopOrderQueue<StateId> *Construct(const Fst<Arc> &fst,
const std::vector<Weight> *) {
return new TopOrderQueue<StateId>(fst, ArcFilter());
}
};
template <class Arc, class Queue, class ArcFilter>
void ShortestDistance(const Fst<Arc> &fst,
std::vector<typename Arc::Weight> *distance,
const ShortestDistanceOptions &opts) {
std::unique_ptr<Queue> queue(
QueueConstructor<Arc, Queue, ArcFilter>::Construct(fst, distance));
const fst::ShortestDistanceOptions<Arc, Queue, ArcFilter> sopts(
queue.get(), ArcFilter(), opts.source, opts.delta);
ShortestDistance(fst, distance, sopts);
}
template <class Arc, class Queue>
void ShortestDistance(const Fst<Arc> &fst,
std::vector<typename Arc::Weight> *distance,
const ShortestDistanceOptions &opts) {
switch (opts.arc_filter_type) {
case ANY_ARC_FILTER: {
ShortestDistance<Arc, Queue, AnyArcFilter<Arc>>(fst, distance, opts);
return;
}
case EPSILON_ARC_FILTER: {
ShortestDistance<Arc, Queue, EpsilonArcFilter<Arc>>(fst, distance, opts);
return;
}
case INPUT_EPSILON_ARC_FILTER: {
ShortestDistance<Arc, Queue, InputEpsilonArcFilter<Arc>>(fst, distance,
opts);
return;
}
case OUTPUT_EPSILON_ARC_FILTER: {
ShortestDistance<Arc, Queue, OutputEpsilonArcFilter<Arc>>(fst, distance,
opts);
return;
}
default: {
FSTERROR() << "ShortestDistance: Unknown arc filter type: "
<< opts.arc_filter_type;
distance->clear();
distance->resize(1, Arc::Weight::NoWeight());
return;
}
}
}
} // namespace internal
using ShortestDistanceArgs1 =
std::tuple<const FstClass &, std::vector<WeightClass> *,
const ShortestDistanceOptions &>;
template <class Arc>
void ShortestDistance(ShortestDistanceArgs1 *args) {
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
const Fst<Arc> &fst = *(std::get<0>(*args).GetFst<Arc>());
const auto &opts = std::get<2>(*args);
std::vector<Weight> typed_distance;
switch (opts.queue_type) {
case AUTO_QUEUE: {
internal::ShortestDistance<Arc, AutoQueue<StateId>>(fst, &typed_distance,
opts);
break;
}
case FIFO_QUEUE: {
internal::ShortestDistance<Arc, FifoQueue<StateId>>(fst, &typed_distance,
opts);
break;
}
case LIFO_QUEUE: {
internal::ShortestDistance<Arc, LifoQueue<StateId>>(fst, &typed_distance,
opts);
break;
}
case SHORTEST_FIRST_QUEUE: {
internal::ShortestDistance<Arc,
NaturalShortestFirstQueue<StateId, Weight>>(
fst, &typed_distance, opts);
break;
}
case STATE_ORDER_QUEUE: {
internal::ShortestDistance<Arc, StateOrderQueue<StateId>>(
fst, &typed_distance, opts);
break;
}
case TOP_ORDER_QUEUE: {
internal::ShortestDistance<Arc, TopOrderQueue<StateId>>(
fst, &typed_distance, opts);
break;
}
default: {
FSTERROR() << "ShortestDistance: Unknown queue type: " << opts.queue_type;
typed_distance.clear();
typed_distance.resize(1, Arc::Weight::NoWeight());
break;
}
}
internal::CopyWeights(typed_distance, std::get<1>(*args));
}
using ShortestDistanceArgs2 =
std::tuple<const FstClass &, std::vector<WeightClass> *, bool, double>;
template <class Arc>
void ShortestDistance(ShortestDistanceArgs2 *args) {
using Weight = typename Arc::Weight;
const Fst<Arc> &fst = *(std::get<0>(*args).GetFst<Arc>());
std::vector<Weight> typed_distance;
ShortestDistance(fst, &typed_distance, std::get<2>(*args),
std::get<3>(*args));
internal::CopyWeights(typed_distance, std::get<1>(*args));
}
void ShortestDistance(const FstClass &fst, std::vector<WeightClass> *distance,
const ShortestDistanceOptions &opts);
void ShortestDistance(const FstClass &ifst, std::vector<WeightClass> *distance,
bool reverse = false,
double delta = fst::kShortestDelta);
} // namespace script
} // namespace fst
#endif // FST_SCRIPT_SHORTEST_DISTANCE_H_
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