@vltpkg/dss-parser

The Dependency Selector Syntax parser used by the vlt client.

Uses postcss-selector-parser to parse a selector string into an AST.

Usage

import { parse } from '@vltpkg/dss-parser'

// Parse a selector string into an AST
const ast = parse(':root > *')

Validation

parse() throws a SyntaxError on invalid DSS, with cause.code EQUERY and the offending input in cause.found. Rejected:

• malformed syntax, e.g. :outdated(, [name=
• empty / whitespace-only queries and empty selectors (#a,, :not())
• unknown pseudo-classes, combinators and attribute operators
• dangling combinators, e.g. :root >, > >
• bare words, strings, empty ids / attributes, e.g. foo, .dev, "foo", #, []

:is() arguments are a forgiving list: only the last group above is rejected there.

Pass { loose: true } to skip the DSS checks (malformed syntax still throws):

parse('#a, :unknown', { loose: true }) // no throw

Supported names are exported as pseudoClassNames, combinatorNames and attributeOperatorNames.