subtask_generators.h

#ifndef CEGAR_SUBTASK_GENERATORS_H
#define CEGAR_SUBTASK_GENERATORS_H
 
#include <memory>
#include <vector>
 
class AbstractTask;
struct FactPair;
 
namespace landmarks {
class LandmarkGraph;
}
 
namespace utils {
class RandomNumberGenerator;
class LogProxy;
} // namespace utils
 
namespace cartesian_abstractions {
using Facts = std::vector<FactPair>;
using SharedTasks = std::vector<std::shared_ptr<AbstractTask>>;
 
enum class FactOrder { ORIGINAL, RANDOM, HADD_UP, HADD_DOWN };
 
/*
  Create focused subtasks.
*/
class SubtaskGenerator {
public:
    virtual SharedTasks get_subtasks(
        const std::shared_ptr<AbstractTask>& task,
        utils::LogProxy& log) const = 0;
    virtual ~SubtaskGenerator() = default;
};
 
/*
  Return copies of the original task.
*/
class TaskDuplicator : public SubtaskGenerator {
    int num_copies;
 
public:
    explicit TaskDuplicator(int copies);
 
    virtual SharedTasks get_subtasks(
        const std::shared_ptr<AbstractTask>& task,
        utils::LogProxy& log) const override;
};
 
/*
  Use ModifiedGoalsTask to return a subtask for each goal fact.
*/
class GoalDecomposition : public SubtaskGenerator {
    FactOrder fact_order;
    std::shared_ptr<utils::RandomNumberGenerator> rng;
 
public:
    explicit GoalDecomposition(FactOrder order, int random_seed);
 
    virtual SharedTasks get_subtasks(
        const std::shared_ptr<AbstractTask>& task,
        utils::LogProxy& log) const override;
};
 
/*
  Nest ModifiedGoalsTask and DomainAbstractedTask to return subtasks
  focussing on a single landmark fact.
*/
class LandmarkDecomposition : public SubtaskGenerator {
    FactOrder fact_order;
    bool combine_facts;
    std::shared_ptr<utils::RandomNumberGenerator> rng;
 
    /* Perform domain abstraction by combining facts that have to be
       achieved before a given landmark can be made true. */
    std::shared_ptr<AbstractTask> build_domain_abstracted_task(
        const std::shared_ptr<AbstractTask>& parent,
        const landmarks::LandmarkGraph& landmark_graph,
        const FactPair& fact) const;
 
public:
    explicit LandmarkDecomposition(
        FactOrder order,
        int random_seed,
        bool combine_facts);
 
    virtual SharedTasks get_subtasks(
        const std::shared_ptr<AbstractTask>& task,
        utils::LogProxy& log) const override;
};
} // namespace cartesian_abstractions
 
#endif