1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
import { Enum, constructors, match } from './utils/adt';
import * as P from './utils/parser-comb'
export type Expr = Enum<{
Call: { name: string, args: Expr[] }
Var: { name: string, defaultValue: Expr }
Identifier: string
LiteralString: string
}>
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 identifierParser = P.regex(/^[a-z][a-z0-9]+/i)
const identifierExprParser = P.map(identifierParser, ident => Expr.Identifier(ident))
const callParser = P.map(P.zip2(
consumeWhitespace(identifierParser),
P.between(P.string('('), consumeWhitespace(identifierParser), P.string(')')),
), ([name, rest]) => Expr.Call({ name, args: [Expr.Identifier(rest)] }))
const exprParser: P.Parser<Expr> = P.or([
callParser,
identifierExprParser,
])
export const parse = (input: string): Expr => {
const res = exprParser(input.trim());
return match(res, {
Ok: ({ value }) => value,
Err: ({ error, input }) => {
throw new Error(`${error}.\n Left input: ${input.slice(0, 20)}...`)
},
})
}
|
