metadata.h

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// Luanti
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
#pragma once
 
#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;
};