metadata.h

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/*
Minetest
Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.
 
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
 
#pragma once
 
#include "irr_v3d.h"
#include <iostream>
#include <vector>
#include "util/string.h"
 
// Basic metadata interface
class IMetadata
{
public:
    virtual ~IMetadata() = default;
 
    virtual void clear() = 0;
 
    bool operator==(const IMetadata &other) const;
    inline bool operator!=(const IMetadata &other) const
    {
        return !(*this == other);
    }
 
    //
    // Key-value related
    //
 
    virtual bool contains(const std::string &name) const = 0;
 
    // May (not must!) put a string in `place` and return a reference to that string.
    const std::string &getString(const std::string &name, std::string *place,
            u16 recursion = 0) const;
 
    // If the entry is present, puts the value in str and returns true;
    // otherwise just returns false.
    bool getStringToRef(const std::string &name, std::string &str, u16 recursion = 0) const;
 
    // Returns whether the metadata was (potentially) changed.
    virtual bool setString(const std::string &name, std::string_view var) = 0;
 
    inline bool removeString(const std::string &name) { return setString(name, ""); }
 
    // May (not must!) put strings in `place` and return a reference to these strings.
    virtual const StringMap &getStrings(StringMap *place) const = 0;
 
    // May (not must!) put keys in `place` and return a reference to these keys.
    virtual const std::vector<std::string> &getKeys(std::vector<std::string> *place) const = 0;
 
    // Add support for variable names in values. Uses place like getString.
    const std::string &resolveString(const std::string &str, std::string *place,
            u16 recursion = 0, bool deprecated = false) const;
 
protected:
    // Returns nullptr to indicate absence of value. Uses place like getString.
    virtual const std::string *getStringRaw(const std::string &name,
            std::string *place) const = 0;
};
 
// Simple metadata parent class (in-memory storage)
class SimpleMetadata: public virtual IMetadata
{
    bool m_modified = false;
public:
    virtual ~SimpleMetadata() = default;
 
    virtual void clear() override;
    virtual bool empty() const;
 
    //
    // Key-value related
    //
 
    size_t size() const;
    bool contains(const std::string &name) const override;
    virtual bool setString(const std::string &name, std::string_view var) override;
    const StringMap &getStrings(StringMap *) const override final;
    const std::vector<std::string> &getKeys(std::vector<std::string> *place)
        const override final;
 
    // Simple version of getters, possible due to in-memory storage:
 
    inline const std::string &getString(const std::string &name, u16 recursion = 0) const
    {
        return IMetadata::getString(name, nullptr, recursion);
    }
 
    inline const std::string &resolveString(const std::string &str, u16 recursion = 0) const
    {
        return IMetadata::resolveString(str, nullptr, recursion);
    }
 
    inline const StringMap &getStrings() const
    {
        return SimpleMetadata::getStrings(nullptr);
    }
 
    inline bool isModified() const  { return m_modified; }
    inline void setModified(bool v) { m_modified = v; }
 
protected:
    StringMap m_stringvars;
 
    const std::string *getStringRaw(const std::string &name,
            std::string *) const override final;
};