THUAI6/CAPI/cpp/grpc/include/upb/extension_registry.h

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#ifndef UPB_EXTENSION_REGISTRY_H_
#define UPB_EXTENSION_REGISTRY_H_

#include <stddef.h>

#include "upb/upb.h"

#ifdef __cplusplus
extern "C"
{
#endif

    /* Extension registry: a dynamic data structure that stores a map of:
     *   (upb_MiniTable, number) -> extension info
     *
     * upb_decode() uses upb_ExtensionRegistry to look up extensions while parsing
     * binary format.
     *
     * upb_ExtensionRegistry is part of the mini-table (msglayout) family of
     * objects. Like all mini-table objects, it is suitable for reflection-less
     * builds that do not want to expose names into the binary.
     *
     * Unlike most mini-table types, upb_ExtensionRegistry requires dynamic memory
     * allocation and dynamic initialization:
     * * If reflection is being used, then upb_DefPool will construct an appropriate
     *   upb_ExtensionRegistry automatically.
     * * For a mini-table only build, the user must manually construct the
     *   upb_ExtensionRegistry and populate it with all of the extensions the user
     * cares about.
     * * A third alternative is to manually unpack relevant extensions after the
     *   main parse is complete, similar to how Any works. This is perhaps the
     *   nicest solution from the perspective of reducing dependencies, avoiding
     *   dynamic memory allocation, and avoiding the need to parse uninteresting
     *   extensions.  The downsides are:
     *     (1) parse errors are not caught during the main parse
     *     (2) the CPU hit of parsing comes during access, which could cause an
     *         undesirable stutter in application performance.
     *
     * Users cannot directly get or put into this map. Users can only add the
     * extensions from a generated module and pass the extension registry to the
     * binary decoder.
     *
     * A upb_DefPool provides a upb_ExtensionRegistry, so any users who use
     * reflection do not need to populate a upb_ExtensionRegistry directly.
     */

    struct upb_ExtensionRegistry;
    typedef struct upb_ExtensionRegistry upb_ExtensionRegistry;

    /* Creates a upb_ExtensionRegistry in the given arena.  The arena must outlive
     * any use of the extreg. */
    upb_ExtensionRegistry* upb_ExtensionRegistry_New(upb_Arena* arena);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* UPB_EXTENSION_REGISTRY_H_ */