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
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
import { flow, pipe } from 'fp-ts/function'
import * as Either from 'fp-ts/Either'
import * as Option from 'fp-ts/Option'
import { fst, mapFst, mapSnd, snd } from 'fp-ts/Tuple'
import { eq } from '../utils'
import { flatten, prepend } from 'fp-ts/Array'
export type char = string
export type ParserState<T> = [T, string]
export type ParserError = [string, string]
export type ParserResult<T> = Either.Either<ParserError, ParserState<T>>
export type Parser<T> = (input: string) => ParserResult<T>
export const constP =
<T>(v: T): Parser<T> =>
(inp: string) =>
Either.right([v, inp])
export const sepBy1 = <T>(sep: Parser<any>, parser: Parser<T>): Parser<T[]> =>
flow(
parser,
Either.chain(([val, nextInput]) =>
pipe(
nextInput,
many0(prefixed(sep, parser)),
Either.map(mapFst(prepend(val))),
),
),
)
export const not =
(parser: Parser<any>): Parser<never> =>
(input: string) =>
pipe(
input,
parser,
Either.fold(
([_left, inp]) => Either.right([null as never, inp]),
([_right, inp]) =>
Either.left(['`not` parser failed. Match found', inp]),
),
)
export const manyTill = <T>(
parser: Parser<T>,
end: Parser<any>,
): Parser<T[]> => {
const p = pair(many0(suffixed(parser, not(end))), suffixed(parser, end))
return mapTo(p, ([xs, l]) => xs.concat([l]))
}
export const many0 = <T>(parser: Parser<T>): Parser<Array<T>> =>
flow(
parser,
Either.chain(([a, nextInput]) =>
pipe(nextInput, many0(parser), Either.map(mapFst(prepend(a)))),
),
Either.orElse(
flow(
mapFst(_ => [] as T[]),
Either.right,
),
),
)
export const many1 = <T>(parser: Parser<T>): Parser<Array<T>> =>
recoverInput(
flow(
many0(parser),
Either.chain(([res, inp]) =>
res.length > 0
? Either.right([res, inp])
: Either.left([`many1 failed to parse at '${inp}'`, inp]),
),
),
)
const recoverInput =
<T>(p: Parser<T>): Parser<T> =>
(input: string) =>
pipe(
input,
p,
Either.orElseW(
flow(
mapSnd(_ => input),
Either.left,
),
),
)
export const prefixed = <T>(a: Parser<any>, b: Parser<T>): Parser<T> =>
recoverInput(mapTo(pair(a, b), snd))
export const suffixed = <T>(a: Parser<T>, b: Parser<any>): Parser<T> =>
recoverInput(mapTo(pair(a, b), fst))
export const delimited = <T>(
p: Parser<any>,
a: Parser<T>,
s: Parser<any>,
): Parser<T> => suffixed(prefixed(p, a), s)
export const satisfyChar =
(f: (c: char) => boolean): Parser<char> =>
(input: string) => {
if (input.length === 0)
return Either.left(['Unexpected end of input', input])
const c = input.charAt(0)
if (f(c)) return Either.right([c, input.slice(1)])
return Either.left([`Expected to satisfy ${f}, got "${c}"`, input])
}
export const digit = satisfyChar(c => /^[0-9]$/g.test(c))
export const digits: Parser<string> = flow(
many1(digit),
Either.map(mapFst(ds => ds.join(''))),
)
export const or = <T>(parsers: Parser<T>[]): Parser<T> => {
const run = ([p, ...ps]: Parser<T>[]) =>
flow(
p,
Either.orElse(([_, inp]) => or(ps)(inp)),
)
return parsers.length > 0
? run(parsers)
: (inp: string) => Either.left(['unable to match', inp])
}
export const matchChar = (ch: char): Parser<char> => satisfyChar(eq(ch))
export const matchString =
(s: string): Parser<string> =>
(input: string) =>
input.slice(0, s.length) === s
? Either.right([s, input.slice(s.length)])
: Either.left([`Expected ${s} but got ${input.slice(0, 1)}`, input])
export const oneOf = (xs: string[]): Parser<string> => or(xs.map(matchString))
export const whitespace = oneOf([' ', '\n', '\t'])
export const whitespaces0 = many0(whitespace)
export const symbol = (s: string): Parser<string> =>
delimited(whitespaces0, matchString(s), whitespaces0)
export const mapTo = <I, R>(p: Parser<I>, f: (p: I) => R): Parser<R> =>
flow(p, Either.map(mapFst(f)))
export const andThen =
<I, R>(f: (p: I) => Parser<R>) =>
(p: Parser<I>): Parser<R> =>
flow(
p,
Either.chain(([v, inp]) => f(v)(inp)),
)
export const optional = <T>(p: Parser<T>): Parser<Option.Option<T>> =>
flow(
recoverInput(p),
Either.fold(
flow(
mapFst(_ => Option.none),
Either.right,
),
flow(mapFst(Option.some), Either.right),
),
)
export const pair = <A, B>(a: Parser<A>, b: Parser<B>): Parser<[A, B]> =>
recoverInput(
pipe(
a,
andThen(ra => mapTo(b, rb => [ra, rb])),
),
)
export const tuple3 = <A, B, C>(
a: Parser<A>,
b: Parser<B>,
c: Parser<C>,
): Parser<[A, B, C]> =>
recoverInput(mapTo(pair(pair(a, b), c), ([[a, b], c]) => [a, b, c]))
|
