Module parser 

Recursive-descent parser for the Media Queries Level 4 grammar, built on top of the crate::tokenizer::Tokenizer from phase 02.

One function per grammar production (see the doc comment on each function below for the production it implements), mirroring the structure of the grammar in plan/03-grammar.md §“Grammatik- Produktionen”.

Parsing approach — no tokenizer backtracking. <media-in-parens> has three alternatives behind the same opening ( (or function token). Instead of backtracking the main token stream, the content of a parenthesized block is first consumed as one atomic token block (analogous to “Consume a simple block”, CSS Syntax Level 3 §5.4.8: all tokens up to the mirror closing token, respecting nested brackets), then <media-condition> and <media-feature> are tried in turn against that isolated token slice. If both fail, the block is kept verbatim as <general-enclosed> (see ast::GeneralEnclosed) — lookahead stays confined to the bracket content instead of needing true backtracking on the main stream.

Error handling. Two distinct failure kinds exist per spec §3.2: a syntax error a parser can’t even parse as a block (e.g. unbalanced parentheses) is a real error, represented by ParseError / Result. A single <media-query> list entry that is syntactically well-formed as a block but doesn’t match the grammar (e.g. an unknown media feature) is, per spec, a browser-matching concern (UAs replace it with not all) — this crate has no “matches” concept (see CLAUDE.md), so parse_media_query_list surfaces the actual per-entry Result instead of silently rewriting it.

Enums

ParseError

A real syntax error, distinct from a <media-query> that is syntactically well-formed but doesn’t match the grammar (see the module doc comment). One variant per failure cause.

Functions

parse_media_query

Parses input as a single <media-query>.

parse_media_query_list

Parses input as a <media-query-list>: a comma-separated list of component values (spec §3), with each entry parsed independently as a <media-query>. Returns one Result per entry rather than a single MediaQueryList/error, since a single invalid entry must not invalidate the rest of the list (see the module doc comment).