one/include/ObjectCollection.h

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/* Copyright 2002-2023, OpenNebula Project, OpenNebula Systems                */
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/* Licensed under the Apache License, Version 2.0 (the "License"); you may    */
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/* distributed under the License is distributed on an "AS IS" BASIS,          */
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/* -------------------------------------------------------------------------- */

#ifndef OBJECT_COLLECTION_H_
#define OBJECT_COLLECTION_H_

#include <set>
#include <vector>
#include <string>
#include <libxml/tree.h>

class ObjectXML;

/**
 *  Class to store a set of PoolObjectSQL IDs.
 */
class ObjectCollection
{
public:

    ObjectCollection(const std::string& _collection_name)
        :collection_name(_collection_name) {};

    ObjectCollection(const std::string& cname, const std::set<int>& cset)
        :collection_name(cname), collection_set(cset) {};

    template <typename T> ObjectCollection(const std::string& cname, const std::vector<T>& cvector)
        :collection_name(cname)
    {
        for (const auto& i: cvector)
        {
            collection_set.insert(static_cast<int>(i));
        }

    }

    ~ObjectCollection() {};

    /**
     *  Adds an ID to the set.
     *    @param id The new id
     *
     *    @return 0 on success, -1 if the ID was already in the set
     */
    int add(int id);

    template <typename T>
    void add(const T& collection)
    {
        for (const auto& i: collection)
        {
            collection_set.insert(static_cast<int>(i));
        }
    }

    /**
     *  Deletes an ID from the set.
     *    @param id The id
     *
     *    @return 0 on success, -1 if the ID was not in the set
     */
    int del(int id);

    /**
     *  Deletes IDs not present in the base collection
     *    @param base the reference collection
     *
     *    @return number of elements deleted
     */
    int del_not_present(const ObjectCollection& base);

    /**
     *  Deletes all IDs from the set.
     */
    void clear()
    {
        collection_set.clear();
    }

    /**
     *  Returns how many IDs are there in the set.
     *    @return how many IDs are there in the set.
     */
    int size() const
    {
        return collection_set.size();
    };

    /**
     * Rebuilds the object from an xml object
     * @param xml xml object
     * @param xpath_prefix Parent nodes, e.g. "/DATASTORE/"
     *
     * @return 0 on success, -1 otherwise
     */
    int from_xml(const ObjectXML* xml, const std::string& xpath_prefix);

    /**
     * Function to print the Collection object into a string in
     * XML format
     *  @param xml the resulting XML string
     *  @return a reference to the generated string
     */
    std::string& to_xml(std::string& xml) const;

    /**
     *  Returns a reference to the IDs set
     */
    const std::set<int>& get_collection() const
    {
        return collection_set;
    };

    /**
     * Returns true if the collection contains the given id
     * @param id ID to search
     * @return true if the collection contains the given id
     */
    bool contains(int id) const
    {
        return collection_set.count(id) > 0;
    }

    /**
     *  Returns and deletes the first element from the set
     *    @param the element
     *    @return 0 on success -1 if the set was empty
     */
    int pop(int& elem);

    /**
     * Adds to the collection the contents of other collection
     *
     */
    ObjectCollection& operator<<(const ObjectCollection& r);

    ObjectCollection& operator<<(const std::set<int>& r);

    /**
     *  Compute the set difference (substract elements in the right hand side
     *  from this collection)
     */
    ObjectCollection& operator-=(const ObjectCollection& r);

    ObjectCollection& operator-=(const std::set<int>& r);

private:

    /**
     *  The collection's name
     */
    std::string  collection_name;

    /**
     *  Set containing the relations IDs
     */
    std::set<int> collection_set;

    /**
     *  Rebuilds the object from an xml node
     *    @param node The xml node pointer
     *
     *    @return 0 on success, -1 otherwise
     */
    int from_xml_node(const xmlNodePtr node);
};

#endif /*OBJECT_COLLECTION_H_*/