Module fill 

Location filters and fill fetch streams, the two things draft-23 asks a subscriber to build byte by byte.

The range of a FETCH travels in the LOCATION_FILTER message parameter (Section 9.19.9), and FILL_PARAMETERS (Section 9.19.15) is a parameter whose presence on a SUBSCRIBE or a REQUEST_UPDATE asks the publisher to open a fill fetch stream, and whose value is a nested parameter block that overrides the subscription’s own settings for that fill alone.

Both are parameter values a caller would otherwise have to construct by hand, which is why they are here: neither carries anything a receiver could resynchronise on, so getting either wrong desynchronises the whole parameter list rather than producing a recognisable error. A LOCATION_FILTER has no length at all — its Location Filter Type is the only thing that says where it ends — and FILL_PARAMETERS is the place draft-23 is least explicit.

What this module decides, and where the draft is silent

• A FILL_PARAMETERS value’s Type Delta chain restarts at 0. See FillParameters.
• A fill fetch stream with no GROUP_ORDER anywhere is read Ascending. See group_order.

Every value this module builds is handed to the codec’s own decoder before it is returned, so a disagreement between the two is an error here rather than a frame on the wire.

Ranges are inclusive

Draft-23 Section 3.3.1 says a Location filter “specifies an inclusive range of Locations”, and Section 3.2 that a FETCH requests Objects “between a Start Location and an End Location, inclusive”. Nothing in this module adds or subtracts one from an end location.

Re-exports

use moqtap_codec::draft23::data_stream::GroupOrder; 🔒

use moqtap_codec::draft23::message::decode_fill_parameters; 🔒

use moqtap_codec::draft23::message::decode_location_filter; 🔒

use moqtap_codec::draft23::message::location_filter_types; 🔒

use moqtap_codec::draft23::message::FILL_PARAMETERS; 🔒

use moqtap_codec::draft23::message::LOCATION_FILTER; 🔒

use moqtap_codec::kvp::KeyValuePair; 🔒

use moqtap_codec::kvp::KvpValue; 🔒

use moqtap_codec::varint::Moqt18 as Wire; 🔒

use moqtap_codec::varint::VarInt; 🔒

Structs

FillParameters

A draft-23 FILL_PARAMETERS (Parameter Type 0x23), Section 9.19.15.

LocationFilter

A draft-23 LOCATION_FILTER (Parameter Type 0x21), Section 9.19.9.

Enums

FillError

Errors from building a LOCATION_FILTER or a FILL_PARAMETERS value.

Constants

FILL_PARAMETERS_ALLOWED 🔒

The parameter types draft-23 Section 9.19.15, Table 7 permits inside a FILL_PARAMETERS value, in ascending order.

GROUP_ORDER

GROUP_ORDER, Parameter Type 0x22 (Section 9.19.8).

GROUP_ORDER_ASCENDING 🔒

The GROUP_ORDER value Section 9.19.8 assigns to Ascending.

GROUP_ORDER_DESCENDING 🔒

The GROUP_ORDER value Section 9.19.8 assigns to Descending.

Functions

check_end_group 🔒

encode_group_order 🔒

The Section 9.19.8 value for a Group Order.

encode_nested_value 🔒

Write one nested parameter’s value in the shape its type names.

group_order

The Group Order a fill fetch stream’s Objects arrive in, given the parameters of the SUBSCRIBE (or REQUEST_UPDATE) that asked for the fill.

insert_parameter

Put parameter into parameters at the position ascending type order requires.

is_bare_varint 🔒

Whether a Table 7 parameter’s value is a bare varint.

is_length_prefixed 🔒

Whether a Table 7 parameter’s value carries its own length prefix.

is_uint8 🔒

Whether a Table 7 parameter’s value is a single raw byte rather than a varint or a length-prefixed block.

may_repeat 🔒

The five Range Filters, of which four may be nested. Only these may repeat.

read_group_order 🔒

The GROUP_ORDER in one parameter list, or None if it holds none.