Choice.h

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/*
 * Souffle - A Datalog Compiler
 * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved
 * Licensed under the Universal Permissive License v 1.0 as shown at:
 * - https://opensource.org/licenses/UPL
 * - <souffle root>/licenses/SOUFFLE-UPL.txt
 */
 
/************************************************************************
 *
 * @file Choice.h
 *
 * Defines the Operation of a relational algebra query.
 *
 ***********************************************************************/
 
#pragma once
 
#include "ram/AbstractChoice.h"
#include "ram/Condition.h"
#include "ram/Node.h"
#include "ram/Operation.h"
#include "ram/Relation.h"
#include "ram/RelationOperation.h"
#include "ram/utility/NodeMapper.h"
#include "souffle/utility/MiscUtil.h"
#include "souffle/utility/StreamUtil.h"
#include <cstddef>
#include <iosfwd>
#include <memory>
#include <ostream>
#include <string>
#include <utility>
#include <vector>
 
namespace souffle::ram {
 
/**
 * @class Choice
 * @brief Find a tuple in a relation such that a given condition holds.
 *
 * Only one tuple is returned (if one exists), even
 * if multiple tuples satisfying the condition exist.
 *
 * For example:
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *  QUERY
 *   ...
 *    CHOICE t1 IN A WHERE (t1.x, t1.y) NOT IN A
 *      ...
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
class Choice : public RelationOperation, public AbstractChoice {
public:
    Choice(std::string rel, size_t ident, Own<Condition> cond, Own<Operation> nested,
            std::string profileText = "")
            : RelationOperation(rel, ident, std::move(nested), std::move(profileText)),
              AbstractChoice(std::move(cond)) {}
 
    void apply(const NodeMapper& map) override {
        RelationOperation::apply(map);
        AbstractChoice::apply(map);
    }
 
    Choice* clone() const override {
        return new Choice(relation, getTupleId(), souffle::clone(condition), souffle::clone(&getOperation()),
                getProfileText());
    }
 
    std::vector<const Node*> getChildNodes() const override {
        return {nestedOperation.get(), AbstractChoice::getChildNodes().at(0)};
    }
 
protected:
    void print(std::ostream& os, int tabpos) const override {
        os << times(" ", tabpos);
        os << "CHOICE t" << getTupleId();
        os << " IN " << getRelation();
        os << " WHERE " << getCondition();
        os << std::endl;
        RelationOperation::print(os, tabpos + 1);
    }
 
    bool equal(const Node& node) const override {
        const auto& other = static_cast<const Choice&>(node);
        return RelationOperation::equal(other) && AbstractChoice::equal(other);
    }
};
 
}  // namespace souffle::ram