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import { Enum, constructors, match } from './utils/adt'
import * as P from './utils/parser-comb'
export type CSSUnit = '' | 's' | 'ms'
export type Expr = Enum<{
Call: { name: string; args: Expr[] }
Identifier: string
VarIdentifier: string
LiteralString: string
LiteralNumber: { value: number, unit: CSSUnit }
}>
export const Expr = constructors<Expr>()
const whitespace = P.regex(/^\s*/)
const consumeWhitespace = <A>(p: P.Parser<A>): P.Parser<A> =>
P.between(whitespace, p, whitespace)
const comma = consumeWhitespace(P.string(','))
const parens = <A>(p: P.Parser<A>): P.Parser<A> =>
P.between(P.string('('), p, P.string(')'))
const identifierParser = P.regex(/^[a-z][a-z0-9_-]*/i)
const varIdentifierParser = P.regex(/^--[a-z][a-z0-9-]*/i)
const singleQuote = P.string("'")
const doubleQuote = P.string('"')
const identifierExprParser = P.map(identifierParser, Expr.Identifier)
const varIdentifierExprParser = P.map(varIdentifierParser, Expr.VarIdentifier)
const callExprParser = (input: string) =>
P.map(
P.zip2(
consumeWhitespace(identifierParser),
parens(consumeWhitespace(P.sepBy(exprParser, comma)))
),
([name, args]) => Expr.Call({ name, args })
)(input)
const stringLiteralParser: P.Parser<Expr> = P.map(
P.or([
P.between(singleQuote, P.regex(/^[^']*/), singleQuote),
P.between(doubleQuote, P.regex(/^[^"]*/), doubleQuote),
]),
Expr.LiteralString
)
const numberParser = P.regex(/^[-+]?((\d*\.\d+)|\d+)/)
const numberExprParser: P.Parser<Expr> = P.map(
P.zip2(numberParser, P.optional(P.regex(/^(s|ms)/i))),
([value, unit]) => Expr.LiteralNumber({ value: Number(value), unit: (unit ?? '') as CSSUnit }),
)
const exprParser: P.Parser<Expr> = P.or([
stringLiteralParser,
varIdentifierExprParser,
numberExprParser,
callExprParser,
identifierExprParser,
])
const multiExprParser = P.many1(exprParser)
export const parse = (input: string): Array<Expr> => {
const res = multiExprParser(input.trim())
return match(res, {
Ok: ({ value, input }) => {
if (input) {
throw new Error(`Input not consumed completely here brosky: "${input}"`)
}
return value
},
Err: ({ error, input }) => {
throw new Error(`${error}.\n Left input: ${input.slice(0, 20)}...`)
},
})
}
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