Protocol Buffers - Google's data interchange format (grpc依赖) https://developers.google.com/protocol-buffers/
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// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#ifndef UPB_MINI_TABLE_EXTENSION_REGISTRY_H_
#define UPB_MINI_TABLE_EXTENSION_REGISTRY_H_
#include "upb/mem/arena.h"
#include "upb/mini_table/extension.h"
#include "upb/mini_table/message.h"
// Must be last.
#include "upb/port/def.inc"
#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.
*/
typedef struct upb_ExtensionRegistry upb_ExtensionRegistry;
// Creates a upb_ExtensionRegistry in the given arena.
// The arena must outlive any use of the extreg.
UPB_API upb_ExtensionRegistry* upb_ExtensionRegistry_New(upb_Arena* arena);
UPB_API bool upb_ExtensionRegistry_Add(upb_ExtensionRegistry* r,
const upb_MiniTableExtension* e);
// Adds the given extension info for the array |e| of size |count| into the
// registry. If there are any errors, the entire array is backed out.
// The extensions must outlive the registry.
// Possible errors include OOM or an extension number that already exists.
// TODO: There is currently no way to know the exact reason for failure.
bool upb_ExtensionRegistry_AddArray(upb_ExtensionRegistry* r,
const upb_MiniTableExtension** e,
size_t count);
// Looks up the extension (if any) defined for message type |t| and field
// number |num|. Returns the extension if found, otherwise NULL.
UPB_API const upb_MiniTableExtension* upb_ExtensionRegistry_Lookup(
const upb_ExtensionRegistry* r, const upb_MiniTable* t, uint32_t num);
#ifdef __cplusplus
} /* extern "C" */
#endif
#include "upb/port/undef.inc"
#endif /* UPB_MINI_TABLE_EXTENSION_REGISTRY_H_ */