dvb_si/tables/any.rs
1//! Unified table dispatch: [`AnyTable`].
2//!
3//! [`AnyTable`] is generated from a single declarative list
4//! (`declare_tables!`) — one line per crate-implemented table type.
5//! The list is the single source of truth: it produces the enum, the
6//! `From<T>` conversions, the table_id range dispatcher, and a drift test
7//! that pins each range literal to the type's
8//! [`crate::traits::TableDef::TABLE_ID_RANGES`].
9//!
10//! [`AnyTable::parse`] dispatches on the first byte (table_id) using range
11//! patterns. An unrecognised table_id yields
12//! `AnyTable::Unknown { table_id, raw }` — the full section bytes are
13//! retained.
14//!
15//! [`AnyTable::parse_as`] is a type-keyed thin alias to `T::parse` — it
16//! bypasses dispatch entirely and lets callers obtain, for example, a
17//! [`crate::tables::mpe::MpeDatagramSection`] for a `0x3E` section that the
18//! default dispatcher would route to `DsmccSection`.
19//!
20//! ```
21//! use dvb_common::Serialize;
22//! use dvb_si::tables::AnyTable;
23//! use dvb_si::tables::pat::{Pat, PatEntry};
24//!
25//! // Serialize a small PAT, then dispatch the bytes back through AnyTable::parse.
26//! let pat = Pat {
27//! transport_stream_id: 1, version_number: 0, current_next_indicator: true,
28//! section_number: 0, last_section_number: 0,
29//! entries: vec![PatEntry { program_number: 1, pid: 0x0100 }],
30//! };
31//! let mut section = vec![0u8; pat.serialized_len()];
32//! pat.serialize_into(&mut section).unwrap();
33//!
34//! match AnyTable::parse(§ion).unwrap() {
35//! AnyTable::Pat(parsed) => assert_eq!(parsed.entries[0].pid, 0x0100),
36//! other => panic!("expected Pat, got {other:?}"),
37//! }
38//! ```
39//!
40//! # Adding a table
41//!
42//! 1. Create the module with the wire layout, a `pub const TABLE_ID: u8` (or
43//! `TABLE_ID_FIRST`/`TABLE_ID_LAST` for a range), and the symmetric
44//! [`dvb_common::Parse`]/[`dvb_common::Serialize`] impls + round-trip tests
45//! (copy an existing module).
46//! 2. `impl TableDef` for the type (`TABLE_ID_RANGES` covering the full
47//! table_id range, `NAME` in SCREAMING_SNAKE without the `_section` or
48//! `_table` suffix).
49//! 3. Add one line to the `declare_tables!` invocation below — the enum
50//! variant, dispatcher arm, and drift test entry are generated from it.
51//! If the type should NOT be auto-dispatched (e.g. `MpeDatagramSection`,
52//! whose `0x3E` id is claimed by the `DsmccSection` range), add it to the
53//! `@no_dispatch` section instead.
54//! 4. The disjointness test in `declare_tables_tests` catches any overlapping
55//! range entries automatically — no manual test edits needed.
56
57/// Declares [`AnyTable`] + its dispatcher from one range list.
58///
59/// Each dispatch line is `Variant = [lo..=hi, …] => module::Type[<'a>]`.
60/// The optional trailing `@no_dispatch …` section adds variants that are NOT
61/// reachable from the generated dispatcher — the variant exists for callers
62/// that obtain the type via `AnyTable::parse_as` or direct `T::parse`.
63macro_rules! declare_tables {
64 (
65 $lt:lifetime;
66 $( $variant:ident = [ $( $lo:literal ..= $hi:literal ),+ ] => $($path:ident)::+ $(<$plt:lifetime>)? ),+ $(,)?
67 $( ; @no_dispatch $( $nd_variant:ident => $($nd_path:ident)::+ $(<$nd_plt:lifetime>)? ),+ $(,)? )?
68 ) => {
69 /// Every crate-implemented table, plus an `Unknown` fallthrough.
70 ///
71 /// serde uses external tagging with camelCase variant keys — a parsed
72 /// PAT serializes as `{"pat": {…}}`.
73 /// Variant names map 1:1 to the table modules; see each module for the
74 /// wire layout.
75 ///
76 /// `0x3E` (`datagram_section`) is routed to `DsmccSection` by the
77 /// default dispatcher. The typed MPE view is reachable via
78 /// `AnyTable::parse_as::<MpeDatagramSection>` or
79 /// `MpeDatagramSection::parse` directly; the `MpeDatagram` variant
80 /// exists in this enum for API completeness but is never produced by
81 /// `AnyTable::parse`.
82 #[derive(Debug)]
83 #[cfg_attr(feature = "serde", derive(serde::Serialize))]
84 #[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
85 #[non_exhaustive]
86 pub enum AnyTable<$lt> {
87 $(
88 #[allow(missing_docs)]
89 $variant($($path)::+ $(<$plt>)?),
90 )+
91 $($(
92 #[allow(missing_docs)]
93 $nd_variant($($nd_path)::+ $(<$nd_plt>)?),
94 )+)?
95 /// table_id with no typed implementation; `raw` is the full
96 /// section bytes including the table_id header.
97 Unknown {
98 /// The raw table_id byte.
99 table_id: u8,
100 /// The raw section bytes (full, header included).
101 raw: &$lt [u8],
102 },
103 }
104
105 $(
106 impl<$lt> From<$($path)::+ $(<$plt>)?> for AnyTable<$lt> {
107 fn from(t: $($path)::+ $(<$plt>)?) -> Self {
108 Self::$variant(t)
109 }
110 }
111 )+
112 $($(
113 impl<$lt> From<$($nd_path)::+ $(<$nd_plt>)?> for AnyTable<$lt> {
114 fn from(t: $($nd_path)::+ $(<$nd_plt>)?) -> Self {
115 Self::$nd_variant(t)
116 }
117 }
118 )+)?
119
120 impl<$lt> AnyTable<$lt> {
121 /// All table_id ranges covered by the auto-dispatcher (excludes
122 /// `@no_dispatch` variants). Each entry is `(lo, hi)` inclusive.
123 pub const DISPATCHED_RANGES: &'static [(u8, u8)] =
124 &[$( $( ($lo, $hi) ),+ ),+];
125
126 /// Dispatch one complete section by its table_id (byte 0).
127 ///
128 /// Returns `Err(BufferTooShort)` when `bytes` is empty.
129 /// Unknown table_ids produce `Ok(AnyTable::Unknown { … })`.
130 ///
131 /// # Errors
132 /// - [`crate::Error::BufferTooShort`] — `bytes` is empty.
133 /// - Any parse error from the dispatched type.
134 pub fn parse(bytes: &$lt [u8]) -> crate::Result<Self> {
135 let table_id = *bytes.first().ok_or(crate::Error::BufferTooShort {
136 need: 1,
137 have: 0,
138 what: "section table_id",
139 })?;
140 match table_id {
141 $(
142 $( $lo..=$hi )|+ => {
143 <$($path)::+ as dvb_common::Parse>::parse(bytes).map(Self::$variant)
144 }
145 )+
146 _ => Ok(Self::Unknown { table_id, raw: bytes }),
147 }
148 }
149
150 /// Type-keyed parse: bypass the dispatcher and parse `bytes`
151 /// directly as `T`. Useful for types excluded from the default
152 /// dispatch, e.g.:
153 ///
154 /// ```rust
155 /// use dvb_si::tables::AnyTable;
156 /// use dvb_si::tables::mpe::MpeDatagramSection;
157 ///
158 /// // A deliberately-too-short slice: parse_as propagates the
159 /// // BufferTooShort error from MpeDatagramSection::parse.
160 /// let err = AnyTable::parse_as::<MpeDatagramSection>(&[0x3E, 0x00]);
161 /// assert!(err.is_err());
162 /// ```
163 ///
164 /// # Errors
165 /// Propagates `T::parse` errors.
166 pub fn parse_as<T>(bytes: &$lt [u8]) -> crate::Result<T>
167 where
168 T: crate::traits::TableDef<$lt>,
169 {
170 <T as dvb_common::Parse>::parse(bytes)
171 }
172 }
173
174 #[cfg(test)]
175 mod macro_drift {
176 #[test]
177 fn ranges_match_tabledef() {
178 use crate::traits::TableDef;
179 $(
180 assert_eq!(
181 &[ $( ($lo, $hi) ),+ ][..],
182 <$($path)::+ as TableDef>::TABLE_ID_RANGES,
183 concat!("TABLE_ID_RANGES drift for ", stringify!($variant)),
184 );
185 assert!(
186 !<$($path)::+ as TableDef>::NAME.is_empty(),
187 concat!("empty NAME for ", stringify!($variant)),
188 );
189 )+
190 $($(
191 assert!(
192 !<$($nd_path)::+ as TableDef>::NAME.is_empty(),
193 concat!("empty NAME for no-dispatch ", stringify!($nd_variant)),
194 );
195 )+)?
196 }
197
198 #[test]
199 fn dispatched_ranges_are_disjoint() {
200 // Collect all (lo, hi) pairs, sort by lo, then check no
201 // two adjacent entries overlap.
202 let mut ranges: Vec<(u8, u8)> = vec![
203 $( $( ($lo, $hi), )+ )+
204 ];
205 ranges.sort_by_key(|r| r.0);
206 for w in ranges.windows(2) {
207 let (_, prev_hi) = w[0];
208 let (next_lo, _) = w[1];
209 assert!(
210 next_lo > prev_hi,
211 "overlapping dispatch ranges: {w:?}",
212 );
213 }
214 }
215 }
216 };
217}
218
219declare_tables! {'a;
220 // MPEG-2 systems tables (ISO/IEC 13818-1).
221 Pat = [0x00..=0x00] => crate::tables::pat::Pat,
222 Cat = [0x01..=0x01] => crate::tables::cat::Cat,
223 Pmt = [0x02..=0x02] => crate::tables::pmt::Pmt<'a>,
224 Tsdt = [0x03..=0x03] => crate::tables::tsdt::Tsdt,
225 // DSM-CC sections (ISO/IEC 13818-6) — 0x3E is included; the MPE typed
226 // view (`MpeDatagramSection`) is reachable via `AnyTable::parse_as` or
227 // `MpeDatagramSection::parse`.
228 DsmccSection = [0x3A..=0x3F] => crate::tables::dsmcc::DsmccSection<'a>,
229 // DVB tables (ETSI EN 300 468).
230 Nit = [0x40..=0x41] => crate::tables::nit::Nit<'a>,
231 Sdt = [0x42..=0x42, 0x46..=0x46] => crate::tables::sdt::Sdt<'a>,
232 Bat = [0x4A..=0x4A] => crate::tables::bat::Bat<'a>,
233 Unt = [0x4B..=0x4B] => crate::tables::unt::Unt<'a>,
234 Int = [0x4C..=0x4C] => crate::tables::int::Int<'a>,
235 Sat = [0x4D..=0x4D] => crate::tables::sat::Sat<'a>,
236 Eit = [0x4E..=0x6F] => crate::tables::eit::Eit<'a>,
237 Tdt = [0x70..=0x70] => crate::tables::tdt::Tdt,
238 Rst = [0x71..=0x71] => crate::tables::rst::Rst,
239 St = [0x72..=0x72] => crate::tables::st::St,
240 Tot = [0x73..=0x73] => crate::tables::tot::Tot<'a>,
241 Ait = [0x74..=0x74] => crate::tables::ait::Ait<'a>,
242 Container = [0x75..=0x75] => crate::tables::container::Container<'a>,
243 Rct = [0x76..=0x76] => crate::tables::rct::Rct<'a>,
244 Cit = [0x77..=0x77] => crate::tables::cit::Cit<'a>,
245 MpeFec = [0x78..=0x78] => crate::tables::mpe_fec::MpeFec<'a>,
246 Rnt = [0x79..=0x79] => crate::tables::rnt::Rnt<'a>,
247 MpeIfec = [0x7A..=0x7A] => crate::tables::mpe_ifec::MpeIfec<'a>,
248 ProtectionMessage = [0x7B..=0x7B] => crate::tables::protection_message::ProtectionMessageSection<'a>,
249 DownloadableFontInfo = [0x7C..=0x7C] => crate::tables::downloadable_font_info::DownloadableFontInfoSection<'a>,
250 Dit = [0x7E..=0x7E] => crate::tables::dit::Dit,
251 Sit = [0x7F..=0x7F] => crate::tables::sit::Sit;
252 // MPE datagram_section (ETSI EN 301 192 §7.1): table_id 0x3E overlaps
253 // the DsmccSection range above, so it is NOT auto-dispatched. Use
254 // `AnyTable::parse_as::<MpeDatagramSection>(bytes)` for the typed view.
255 @no_dispatch
256 MpeDatagram => crate::tables::mpe::MpeDatagramSection<'a>,
257}