pgLab/pglablib/PgContainer.h

#ifndef PGCONTAINER_H
#define PGCONTAINER_H

#include "Pgsql_declare.h"
#include "Pgsql_Result.h"
#include <QString>
#include <memory>
#include <vector>
#include <libpq-fe.h>


class PgDatabaseCatalog;

class IPgContainter {
public:
	virtual ~IPgContainter() = default;

	virtual std::string getLoadQuery() const = 0;
	virtual void load(const Pgsql::Result &res) = 0;
};

template<typename T, typename K=Oid>
class PgContainer: public IPgContainter {
public:
	using t_Container = std::vector<T>; ///< Do not assume it will stay a vector only expect bidirectional access

	explicit PgContainer(std::weak_ptr<PgDatabaseCatalog> cat)
		: m_catalogue(cat)
	{}


	typename t_Container::const_iterator begin() const
	{
		return m_container.begin();
	}

	typename t_Container::const_iterator end() const
	{
		return m_container.end();
	}

	void clear()
	{
		m_container.clear();
	}

	int count() const
	{
		return (int)m_container.size();
	}

	const T& getByKey(const K &key) const
	{
		auto lb_result = std::lower_bound(m_container.begin(), m_container.end(), key);
		if (lb_result != m_container.end() && *lb_result == key)
			return *lb_result;

		return m_invalidInstance;
	}

	const T& getByName(const QString &name) const
	{
		auto find_res = std::find(m_container.begin(), m_container.end(), name);

		if (find_res != m_container.end())
			return *find_res;

		return m_invalidInstance;
	}

	const T& getByIdx(int idx) const
	{
		return m_container.at(idx);
	}

	/** Override to implement complete loading logic.
	 *
	 * Do not override this function if you only want to implement
	 * the loading of a single element. Override loadElem instead.
	 */
	virtual void load(const Pgsql::Result &res) override
	{
		m_container.clear();
		m_container.reserve(res.rows());
		for (auto row : res)
			m_container.push_back(loadElem(row));

		std::sort(m_container.begin(), m_container.end());
	}
protected:
	std::weak_ptr<PgDatabaseCatalog> m_catalogue;
	t_Container m_container;

	/** Override the implementation for this function to implement loading of single row.
	 *
	 * When overriding this function there is no need to override load.
	 */
	virtual T loadElem(const Pgsql::Row &) { return m_invalidInstance; }
private:
	T m_invalidInstance;

};


template<typename T, typename K=Oid>
class PgSPtrContainer: public IPgContainter {
public:
	using t_Elem = std::shared_ptr<T>;
	using t_Container = std::vector<t_Elem>; ///< Do not assume it will stay a vector only expect bidirectional access

	explicit PgSPtrContainer(std::weak_ptr<PgDatabaseCatalog> cat)
		: m_catalogue(cat)
	{}


	typename t_Container::const_iterator begin() const
	{
		return m_container.begin();
	}

	typename t_Container::const_iterator end() const
	{
		return m_container.end();
	}

	void clear()
	{
		m_container.clear();
	}

	int count() const
	{
		return (int)m_container.size();
	}

	const t_Elem getByKey(const K &key) const
	{
		auto lb_result = std::lower_bound(m_container.begin(), m_container.end(), key);
		if (lb_result != m_container.end() && **lb_result == key)
			return *lb_result;

		return m_invalidInstance;
	}

	const t_Elem getByName(const QString name) const
	{
		auto find_res = std::find_if(m_container.begin(), m_container.end(),
						[name](auto e) -> bool { return *e = name; } );

		if (find_res != m_container.end())
			return *find_res;

		return m_invalidInstance;
	}

	const t_Elem getByIdx(int idx) const
	{
		return m_container.at(idx);
	}

	/** Override to implement complete loading logic.
	 *
	 * Do not override this function if you only want to implement
	 * the loading of a single element. Override loadElem instead.
	 */
	virtual void load(const Pgsql::Result &res) override
	{
		m_container.clear();
		m_container.reserve(res.rows());
		for (auto row : res)
			m_container.push_back(loadElem(row));

		std::sort(m_container.begin(), m_container.end());
	}
protected:
	std::weak_ptr<PgDatabaseCatalog> m_catalogue;
	t_Container m_container;

	/** Override the implementation for this function to implement loading of single row.
	 *
	 * When overriding this function there is no need to override load.
	 */
	virtual t_Elem loadElem(const Pgsql::Row &) = 0;
private:

};


#endif // PGCONTAINER_H