ClickHouse/base/poco/Foundation/include/Poco/Manifest.h

//
// Manifest.h
//
// Library: Foundation
// Package: SharedLibrary
// Module:  ClassLoader
//
// Definition of the Manifest class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_Manifest_INCLUDED
#define Foundation_Manifest_INCLUDED


#include <map>
#include <typeinfo>
#include "Poco/Foundation.h"
#include "Poco/MetaObject.h"


namespace Poco
{


class Foundation_API ManifestBase
/// ManifestBase is a common base class for
/// all instantiations of Manifest.
{
public:
    ManifestBase();
    virtual ~ManifestBase();

    virtual const char * className() const = 0;
    /// Returns the type name of the manifest's class.
};


template <class B>
class Manifest : public ManifestBase
/// A Manifest maintains a list of all classes
/// contained in a dynamically loadable class
/// library.
/// Internally, the information is held
/// in a map. An iterator is provided to
/// iterate over all the classes in a Manifest.
{
public:
    typedef AbstractMetaObject<B> Meta;
    typedef std::map<std::string, const Meta *> MetaMap;

    class Iterator
    /// The Manifest's very own iterator class.
    {
    public:
        Iterator(const typename MetaMap::const_iterator & it) { _it = it; }
        Iterator(const Iterator & it) { _it = it._it; }
        ~Iterator() { }
        Iterator & operator=(const Iterator & it)
        {
            _it = it._it;
            return *this;
        }
        inline bool operator==(const Iterator & it) const { return _it == it._it; }
        inline bool operator!=(const Iterator & it) const { return _it != it._it; }
        Iterator & operator++() // prefix
        {
            ++_it;
            return *this;
        }
        Iterator operator++(int) // postfix
        {
            Iterator result(_it);
            ++_it;
            return result;
        }
        inline const Meta * operator*() const { return _it->second; }
        inline const Meta * operator->() const { return _it->second; }

    private:
        typename MetaMap::const_iterator _it;
    };

    Manifest()
    /// Creates an empty Manifest.
    {
    }

    virtual ~Manifest()
    /// Destroys the Manifest.
    {
        clear();
    }

    Iterator find(const std::string & className) const
    /// Returns an iterator pointing to the MetaObject
    /// for the given class. If the MetaObject cannot
    /// be found, the iterator points to end().
    {
        return Iterator(_metaMap.find(className));
    }

    Iterator begin() const { return Iterator(_metaMap.begin()); }

    Iterator end() const { return Iterator(_metaMap.end()); }

    bool insert(const Meta * pMeta)
    /// Inserts a MetaObject. Returns true if insertion
    /// was successful, false if a class with the same
    /// name already exists.
    {
        return _metaMap.insert(typename MetaMap::value_type(pMeta->name(), pMeta)).second;
    }

    void clear()
    /// Removes all MetaObjects from the manifest.
    {
        for (typename MetaMap::iterator it = _metaMap.begin(); it != _metaMap.end(); ++it)
        {
            delete it->second;
        }
        _metaMap.clear();
    }

    int size() const
    /// Returns the number of MetaObjects in the Manifest.
    {
        return int(_metaMap.size());
    }

    bool empty() const
    /// Returns true iff the Manifest does not contain any MetaObjects.
    {
        return _metaMap.empty();
    }

    const char * className() const { return typeid(*this).name(); }

private:
    MetaMap _metaMap;
};


} // namespace Poco


#endif // Foundation_Manifest_INCLUDED