Commit | Line | Data |
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6071876f | 1 | import { MalType, MalList, MalString, MalNumber, MalBoolean, MalNil, MalKeyword, MalSymbol, MalVector, MalHashMap } from "./types"; |
f406f88b | 2 | |
3 | class Reader { | |
4 | position = 0; | |
5 | ||
6 | constructor(private tokens: string[]) { } | |
7 | ||
8 | next(): string { | |
9 | const ret = this.peek(); | |
10 | this.position += 1; | |
11 | return ret; | |
12 | } | |
13 | ||
14 | peek(): string { | |
15 | return this.tokens[this.position]; | |
16 | } | |
17 | } | |
18 | ||
19 | export function readStr(input: string): MalType { | |
20 | const tokens = tokenizer(input); | |
21 | const reader = new Reader(tokens); | |
29db6f4e | 22 | return readForm(reader); |
f406f88b | 23 | } |
24 | ||
25 | function tokenizer(input: string): string[] { | |
4aa0ebdf | 26 | const regexp = /[\s,]*(~@|[\[\]{}()'`~^@]|"(?:\\.|[^\\"])*"?|;.*|[^\s\[\]{}('"`,;)]*)/g; |
f406f88b | 27 | const tokens: string[] = []; |
28 | while (true) { | |
29 | const matches = regexp.exec(input); | |
30 | if (!matches) { | |
31 | break; | |
32 | } | |
33 | const match = matches[1]; | |
34 | if (match === "") { | |
35 | break; | |
36 | } | |
37 | if (match[0] !== ";") { | |
38 | tokens.push(match); | |
39 | } | |
40 | } | |
41 | ||
42 | return tokens; | |
43 | } | |
44 | ||
29db6f4e | 45 | function readForm(reader: Reader): MalType { |
f406f88b | 46 | const token = reader.peek(); |
47 | switch (token) { | |
48 | case "(": | |
49 | return readList(reader); | |
50 | case "[": | |
51 | return readVector(reader); | |
52 | case "{": | |
53 | return readHashMap(reader); | |
54 | case "'": | |
55 | return readSymbol("quote"); | |
56 | case "`": | |
57 | return readSymbol("quasiquote"); | |
58 | case "~": | |
59 | return readSymbol("unquote"); | |
60 | case "~@": | |
61 | return readSymbol("splice-unquote"); | |
62 | case "@": | |
63 | return readSymbol("deref"); | |
64 | case "^": | |
65 | { | |
66 | reader.next(); | |
67 | const sym = MalSymbol.get("with-meta"); | |
29db6f4e | 68 | const target = readForm(reader); |
69 | return new MalList([sym, readForm(reader), target]); | |
f406f88b | 70 | } |
71 | default: | |
72 | return readAtom(reader); | |
73 | } | |
74 | ||
75 | function readSymbol(name: string) { | |
76 | reader.next(); | |
77 | const sym = MalSymbol.get(name); | |
29db6f4e | 78 | const target = readForm(reader); |
f406f88b | 79 | return new MalList([sym, target]); |
80 | } | |
81 | } | |
82 | ||
83 | function readList(reader: Reader): MalType { | |
84 | return readParen(reader, MalList, "(", ")"); | |
85 | } | |
86 | ||
87 | function readVector(reader: Reader): MalType { | |
88 | return readParen(reader, MalVector, "[", "]"); | |
89 | } | |
90 | ||
91 | function readHashMap(reader: Reader): MalType { | |
92 | return readParen(reader, MalHashMap, "{", "}"); | |
93 | } | |
94 | ||
95 | function readParen(reader: Reader, ctor: { new (list: MalType[]): MalType; }, open: string, close: string): MalType { | |
96 | const token = reader.next(); // drop open paren | |
97 | if (token !== open) { | |
98 | throw new Error(`unexpected token ${token}, expected ${open}`); | |
99 | } | |
100 | const list: MalType[] = []; | |
101 | while (true) { | |
102 | const next = reader.peek(); | |
103 | if (next === close) { | |
104 | break; | |
105 | } else if (!next) { | |
106 | throw new Error("unexpected EOF"); | |
107 | } | |
29db6f4e | 108 | list.push(readForm(reader)); |
f406f88b | 109 | } |
110 | reader.next(); // drop close paren | |
111 | ||
112 | return new ctor(list); | |
113 | } | |
114 | ||
115 | function readAtom(reader: Reader): MalType { | |
116 | const token = reader.next(); | |
117 | if (token.match(/^-?[0-9]+$/)) { | |
118 | const v = parseInt(token, 10); | |
119 | return new MalNumber(v); | |
120 | } | |
121 | if (token.match(/^-?[0-9]\.[0-9]+$/)) { | |
122 | const v = parseFloat(token); | |
123 | return new MalNumber(v); | |
124 | } | |
125 | if (token[0] === '"') { | |
4aa0ebdf JM |
126 | if (token.slice(-1) !== '"') { |
127 | throw new Error("expected '\"', got EOF"); | |
128 | } | |
f406f88b | 129 | const v = token.slice(1, token.length - 1) |
da9aef12 | 130 | .replace(/\\(.)/g, (_, c: string) => c == 'n' ? '\n' : c) |
f406f88b | 131 | return new MalString(v); |
132 | } | |
133 | if (token[0] === ":") { | |
10f8aa84 | 134 | return MalKeyword.get(token.substr(1)); |
f406f88b | 135 | } |
136 | switch (token) { | |
137 | case "nil": | |
6071876f | 138 | return MalNil.instance; |
f406f88b | 139 | case "true": |
140 | return new MalBoolean(true); | |
141 | case "false": | |
142 | return new MalBoolean(false); | |
143 | } | |
144 | ||
145 | return MalSymbol.get(token); | |
146 | } |