EM_Task/CoreUObject/Public/UObject/MetaData.h

// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "UObject/Object.h"
#include "UObject/WeakObjectPtr.h"

/*-----------------------------------------------------------------------------
        UMetaData.
-----------------------------------------------------------------------------*/

/**
 * An object that holds a map of key/value pairs.
 */
class COREUOBJECT_API UMetaData: public UObject
{
    DECLARE_CLASS_INTRINSIC(UMetaData, UObject, CLASS_MatchedSerializers, TEXT("/Script/CoreUObject"))

public:
    /**
     * Mapping between an object, and its key->value meta-data pairs.
     */
    TMap<FWeakObjectPtr, TMap<FName, FString>> ObjectMetaDataMap;

    /**
     * Root-level (not associated with a particular object) key->value meta-data pairs.
     * Meta-data associated with the package itself should be stored here.
     */
    TMap<FName, FString> RootMetaDataMap;

public:
    // MetaData utility functions

    /**
     * Return the value for the given key in the given property
     * @param Object the object to lookup the metadata for
     * @param Key The key to lookup
     * @return The value if found, otherwise an empty string
     */
    const FString& GetValue(const UObject* Object, const TCHAR* Key);

    /**
     * Return the value for the given key in the given property
     * @param Object the object to lookup the metadata for
     * @param Key The key to lookup
     * @return The value if found, otherwise an empty string
     */
    const FString& GetValue(const UObject* Object, FName Key);

    /**
     * Return whether or not the Key is in the meta data
     * @param Object the object to lookup the metadata for
     * @param Key The key to query for existence
     * @return true if found
     */
    bool HasValue(const UObject* Object, const TCHAR* Key)
    {
        return FindValue(Object, Key) != nullptr;
    }

    /**
     * Return whether or not the Key is in the meta data
     * @param Object the object to lookup the metadata for
     * @param Key The key to query for existence
     * @return true if found
     */
    bool HasValue(const UObject* Object, FName Key)
    {
        return FindValue(Object, Key) != nullptr;
    }

    /**
     * Returns the value for a the given key if it exists, null otherwise
     * @param Object the object to lookup the metadata for
     * @param Key The key to query for existence
     * @return true if found
     */
    const FString* FindValue(const UObject* Object, const TCHAR* Key);

    /**
     * Returns the value for a the given key if it exists, null otherwise
     * @param Object the object to lookup the metadata for
     * @param Key The key to query for existence
     * @return true if found
     */
    const FString* FindValue(const UObject* Object, FName Key);

    /**
     * Is there any metadata for this property?
     * @param Object the object to lookup the metadata for
     * @return TrUE if the object has any metadata at all
     */
    bool HasObjectValues(const UObject* Object);

    /**
     * Set the key/value pair in the Property's metadata
     * @param Object the object to set the metadata for
     * @Values The metadata key/value pairs
     */
    void SetObjectValues(const UObject* Object, const TMap<FName, FString>& Values);

    /**
     * Set the key/value pair in the Property's metadata
     * @param Object the object to set the metadata for
     * @Values The metadata key/value pairs
     */
    void SetObjectValues(const UObject* Object, TMap<FName, FString>&& Values);

    /**
     * Set the key/value pair in the Object's metadata
     * @param Object the object to set the metadata for
     * @param Key A key to set the data for
     * @param Value The value to set for the key
     */
    void SetValue(const UObject* Object, const TCHAR* Key, const TCHAR* Value);

    /**
     * Set the key/value pair in the Property's metadata
     * @param Object the object to set the metadata for
     * @param Key A key to set the data for
     * @param Value The value to set for the key
     * @Values The metadata key/value pairs
     */
    void SetValue(const UObject* Object, FName Key, const TCHAR* Value);

    /**
     *	Remove any entry with the supplied Key form the Property's metadata
     *	@param Object the object to clear the metadata for
     *	@param Key A key to clear the data for
     */
    void RemoveValue(const UObject* Object, const TCHAR* Key);

    /**
     *	Remove any entry with the supplied Key form the Property's metadata
     *	@param Object the object to clear the metadata for
     *	@param Key A key to clear the data for
     */
    void RemoveValue(const UObject* Object, FName Key);

    /** Find the name/value map for metadata for a specific object */
    static TMap<FName, FString>* GetMapForObject(const UObject* Object);

    /** Copy all metadata from the source object to the destination object. This will add to any existing metadata entries for SourceObject. */
    static void CopyMetadata(UObject* SourceObject, UObject* DestObject);

    /**
     * Removes any metadata entries that are to objects not inside the same package as this UMetaData object.
     */
    void RemoveMetaDataOutsidePackage();

    // UObject interface
    virtual void Serialize(FArchive& Ar) override;
    virtual void Serialize(FStructuredArchive::FRecord Record) override;
    virtual bool NeedsLoadForEditorGame() const override;
    virtual bool IsAsset() const override { return false; }
    // End of UObject interface

    // Returns the remapped key name, or NAME_None was not remapped.
    static FName GetRemappedKeyName(FName OldKey);

#if HACK_HEADER_GENERATOR
    // Required by UHT makefiles for internal data serialization.
    friend struct FMetadataArchiveProxy;
#endif

private:
    static void InitializeRedirectMap();

private:
    // Redirect map from deprecated keys to current key names
    static TMap<FName, FName> KeyRedirectMap;
};

#if WITH_EDITOR
struct FMetaDataUtilities
{
private:
    /** Console command for dumping all metadata */
    static class FAutoConsoleCommand DumpAllConsoleCommand;

public:
    /** Find all UMetadata and print its contents to the log */
    COREUOBJECT_API static void DumpAllMetaData();

    /** Output contents of this metadata object to the log */
    COREUOBJECT_API static void DumpMetaData(UMetaData* Object);

private:
    friend class UObject;

    /** Helper class to backup and move the metadata for a given UObject (and optionally its children). */
    class FMoveMetadataHelperContext
    {
    public:
        /**
         * Backs up the metadata for the UObject (and optionally its children).
         *
         * @param	SourceObject		The main UObject to move metadata for.
         * @param	bSearchChildren		When true all the metadata for classes
         */
        FMoveMetadataHelperContext(UObject* SourceObject, bool bSearchChildren);

        /**
         * Patches up the new metadata on destruction.
         */
        ~FMoveMetadataHelperContext();

    private:
        /** Keep the old package around so we can pull in the metadata without actually duplicating it. */
        UPackage* OldPackage;

        /** Cache a pointer to the object so we can do the search on the old metadata. */
        UObject* OldObject;

        /** When true, search children as well. */
        bool bShouldSearchChildren;
    };

private:
    FMetaDataUtilities() {}
};

#endif  // WITH_EDITOR