1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2023 Google LLC. All rights reserved. 3 // 4 // Use of this source code is governed by a BSD-style 5 // license that can be found in the LICENSE file or at 6 // https://developers.google.com/open-source/licenses/bsd 7 8 #ifndef UPB_MESSAGE_INTERNAL_EXTENSION_H_ 9 #define UPB_MESSAGE_INTERNAL_EXTENSION_H_ 10 11 #include "upb/base/string_view.h" 12 #include "upb/mem/arena.h" 13 #include "upb/message/internal/message.h" 14 #include "upb/mini_table/extension.h" 15 16 // Must be last. 17 #include "upb/port/def.inc" 18 19 // The internal representation of an extension is self-describing: it contains 20 // enough information that we can serialize it to binary format without needing 21 // to look it up in a upb_ExtensionRegistry. 22 // 23 // This representation allocates 16 bytes to data on 64-bit platforms. 24 // This is rather wasteful for scalars (in the extreme case of bool, 25 // it wastes 15 bytes). We accept this because we expect messages to be 26 // the most common extension type. 27 struct upb_Extension { 28 const upb_MiniTableExtension* ext; 29 union { 30 upb_StringView str; 31 void* ptr; 32 char scalar_data[8]; 33 } data; 34 }; 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 // Adds the given extension data to the given message. 41 // |ext| is copied into the message instance. 42 // This logically replaces any previously-added extension with this number. 43 struct upb_Extension* UPB_PRIVATE(_upb_Message_GetOrCreateExtension)( 44 struct upb_Message* msg, const upb_MiniTableExtension* ext, 45 upb_Arena* arena); 46 47 // Returns an array of extensions for this message. 48 // Note: the array is ordered in reverse relative to the order of creation. 49 const struct upb_Extension* UPB_PRIVATE(_upb_Message_Getexts)( 50 const struct upb_Message* msg, size_t* count); 51 52 // Returns an extension for a message with a given mini table, 53 // or NULL if no extension exists with this mini table. 54 const struct upb_Extension* UPB_PRIVATE(_upb_Message_Getext)( 55 const struct upb_Message* msg, const upb_MiniTableExtension* ext); 56 57 #ifdef __cplusplus 58 } /* extern "C" */ 59 #endif 60 61 #include "upb/port/undef.inc" 62 63 #endif /* UPB_MESSAGE_INTERNAL_EXTENSION_H_ */ 64