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Diffstat (limited to 'docs/reference.rst')
| -rw-r--r-- | docs/reference.rst | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/docs/reference.rst b/docs/reference.rst index 6c38f6b4..51556d35 100644 --- a/docs/reference.rst +++ b/docs/reference.rst @@ -304,6 +304,41 @@ Protocol Buffers wire types. These are used with `pb_encode_tag`_. :: PB_WT_32BIT = 5 } pb_wire_type_t; +pb_extension_type_t +------------------- +Defines the handler functions and auxiliary data for a field that extends +another message. Usually autogenerated by *nanopb_generator.py*:: + + typedef struct { + bool (*decode)(pb_istream_t *stream, pb_extension_t *extension, + uint32_t tag, pb_wire_type_t wire_type); + bool (*encode)(pb_ostream_t *stream, const pb_extension_t *extension); + const void *arg; + } pb_extension_type_t; + +In the normal case, the function pointers are *NULL* and the decoder and +encoder use their internal implementations. The internal implementations +assume that *arg* points to a *pb_field_t* that describes the field in question. + +To implement custom processing of unknown fields, you can provide pointers +to your own functions. Their functionality is mostly the same as for normal +callback fields, except that they get called for any unknown field when decoding. + +pb_extension_t +-------------- +Ties together the extension field type and the storage for the field value:: + + typedef struct { + const pb_extension_type_t *type; + void *dest; + pb_extension_t *next; + } pb_extension_t; + +:type: Pointer to the structure that defines the callback functions. +:dest: Pointer to the variable that stores the field value + (as used by the default extension callback functions.) +:next: Pointer to the next extension handler, or *NULL*. + PB_GET_ERROR ------------ Get the current error message from a stream, or a placeholder string if |