text: /*
   * Souffle - A Datalog Compiler
   * Copyright (c) 2021, The Souffle Developers. 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 AbstractIfExists.h
   *
   ***********************************************************************/
  
  #pragma once
  
  #include "ram/Condition.h"
  #include "ram/Node.h"
  #include "souffle/utility/ContainerUtil.h"
  #include "souffle/utility/MiscUtil.h"
  #include <cassert>
  #include <memory>
  #include <utility>
  #include <vector>
  
  namespace souffle::ram {
  
  /**
   * @class AbstractIfExists
   * @brief Abstract class for an if-exists  operation
   *
   * Finding a single tuple, if it exists, such that a condition holds.
   */
  class AbstractIfExists {
  public:
      AbstractIfExists(Own<Condition> cond) : condition(std::move(cond)) {
          assert(condition != nullptr && "Condition is a null-pointer");
      }
  
      /** @brief Getter for the condition */
      const Condition& getCondition() const {
          assert(condition != nullptr && "condition of if-exists is a null-pointer");
          return *condition;
      }
  
      void apply(const NodeMapper& map) {
          condition = map(std::move(condition));
      }
  
      Node::ConstChildNodes getChildNodes() const {
          return Node::ConstChildNodes(getChildren(), detail::RefCaster());
      }
  
      Node::ChildNodes getChildNodes() {
          return Node::ChildNodes(getChildren(), detail::ConstCaster());
      }
  
  protected:
      bool equal(const Node& node) const {
          const auto& other = asAssert<AbstractIfExists, AllowCrossCast>(node);
          return equal_ptr(condition, other.condition);
      }
  
      std::vector<const Node*> getChildren() const {
          return {condition.get()};
      }
  
      /** Condition for which a tuple in the relation may hold */
      Own<Condition> condition;
  };
  }  // namespace souffle::ram
  