cocos-engine/native/cocos/base/Data.h

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#pragma once

#include <cstdint> // for ssize_t on android
#include <string>  // for ssize_t on linux
#include "base/Macros.h"

/**
 * @addtogroup base
 * @js NA
 * @lua NA
 */
namespace cc {

class CC_DLL Data {
    friend class Properties;

public:
    /**
     * This parameter is defined for convenient reference if a null Data object is needed.
     */
    static const Data NULL_DATA;

    /**
     * Constructor of Data.
     */
    Data();

    /**
     * Copy constructor of Data.
     */
    Data(const Data &other);

    /**
     * Copy constructor of Data.
     */
    Data(Data &&other) noexcept;

    /**
     * Destructor of Data.
     */
    ~Data();

    /**
     * Overloads of operator=.
     */
    Data &operator=(const Data &other);

    /**
     * Overloads of operator=.
     */
    Data &operator=(Data &&other) noexcept;

    /**
     * Gets internal bytes of Data. It will return the pointer directly used in Data, so don't delete it.
     *
     * @return Pointer of bytes used internal in Data.
     */
    unsigned char *getBytes() const;

    /**
     * Gets the size of the bytes.
     *
     * @return The size of bytes of Data.
     */
    ssize_t getSize() const;

    /** Copies the buffer pointer and its size.
     *  @note This method will copy the whole buffer.
     *        Developer should free the pointer after invoking this method.
     *  @see Data::fastSet
     */
    void copy(const unsigned char *bytes, ssize_t size);

    /** Fast set the buffer pointer and its size. Please use it carefully.
     *  @param bytes The buffer pointer, note that it have to be allocated by 'malloc' or 'calloc',
     *         since in the destructor of Data, the buffer will be deleted by 'free'.
     *  @note 1. This method will move the ownship of 'bytes'pointer to Data,
     *        2. The pointer should not be used outside after it was passed to this method.
     *  @see Data::copy
     */
    void fastSet(unsigned char *bytes, ssize_t size);

    void resize(ssize_t size);

    /**
     * Clears data, free buffer and reset data size.
     */
    void clear();

    /**
     * Check whether the data is null.
     *
     * @return True if the Data is null, false if not.
     */
    bool isNull() const;

    /**
     * Get the internal buffer of data and set data to empty state.
     *
     * The ownership of the buffer removed from the data object.
     * That is the user have to free the returned buffer.
     * The data object is set to empty state, that is internal buffer is set to nullptr
     * and size is set to zero.
     * Usage:
     * @code
     *  Data d;
     *  // ...
     *  ssize_t size;
     *  unsigned char* buffer = d.takeBuffer(&size);
     *  // use buffer and size
     *  free(buffer);
     * @endcode
     *
     * @param size Will fill with the data buffer size in bytes, if you do not care buffer size, pass nullptr.
     * @return the internal data buffer, free it after use.
     */
    unsigned char *takeBuffer(ssize_t *size = nullptr);

private:
    void move(Data &other); //NOLINT

private:
    unsigned char *_bytes;
    ssize_t        _size;
};

} // namespace cc