| 1 | /** |
| 2 | * Tokenizer for the GitHub Actions expression language |
| 3 | * (https://docs.github.com/en/actions/learn-github-actions/expressions). |
| 4 | */ |
| 5 | |
| 6 | export type TokenKind = |
| 7 | | "number" |
| 8 | | "string" |
| 9 | | "ident" |
| 10 | | "true" |
| 11 | | "false" |
| 12 | | "null" |
| 13 | | "(" |
| 14 | | ")" |
| 15 | | "[" |
| 16 | | "]" |
| 17 | | "." |
| 18 | | "," |
| 19 | | "*" |
| 20 | | "!" |
| 21 | | "<" |
| 22 | | "<=" |
| 23 | | ">" |
| 24 | | ">=" |
| 25 | | "==" |
| 26 | | "!=" |
| 27 | | "&&" |
| 28 | | "||" |
| 29 | | "eof"; |
| 30 | |
| 31 | export interface Token { |
| 32 | kind: TokenKind; |
| 33 | /** Raw source text of the token. */ |
| 34 | text: string; |
| 35 | /** Parsed value for number/string literals. */ |
| 36 | value?: number | string; |
| 37 | /** Offset in the expression source. */ |
| 38 | pos: number; |
| 39 | } |
| 40 | |
| 41 | export class ExpressionSyntaxError extends Error { |
| 42 | constructor( |
| 43 | message: string, |
| 44 | readonly expression: string, |
| 45 | readonly pos: number, |
| 46 | ) { |
| 47 | super(`${message} (at position ${pos + 1} in expression: ${expression})`); |
| 48 | this.name = "ExpressionSyntaxError"; |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | const isDigit = (c: string | undefined): boolean => c !== undefined && c >= "0" && c <= "9"; |
| 53 | const isIdentStart = (c: string | undefined): boolean => |
| 54 | c !== undefined && ((c >= "a" && c <= "z") || (c >= "A" && c <= "Z") || c === "_"); |
| 55 | const isIdentPart = (c: string | undefined): boolean => isIdentStart(c) || isDigit(c) || c === "-"; |
| 56 | |
| 57 | const NUMBER_RE = /^[+-]?(?:0[xX][0-9a-fA-F]+|0[oO][0-7]+|(?:\d+\.?\d*|\.\d+)(?:[eE][+-]?\d+)?)/; |
| 58 | |
| 59 | /** Parses the numeric literal syntax used by GitHub (JSON numbers, hex, octal, exponent). */ |
| 60 | export function parseNumberLiteral(text: string): number { |
| 61 | const t = text.trim(); |
| 62 | const sign = t.startsWith("-") ? -1 : 1; |
| 63 | const body = t.replace(/^[+-]/, ""); |
| 64 | if (/^0[xX][0-9a-fA-F]+$/.test(body)) return sign * parseInt(body.slice(2), 16); |
| 65 | if (/^0[oO][0-7]+$/.test(body)) return sign * parseInt(body.slice(2), 8); |
| 66 | return Number(t); |
| 67 | } |
| 68 | |
| 69 | export function tokenize(src: string): Token[] { |
| 70 | const tokens: Token[] = []; |
| 71 | let i = 0; |
| 72 | const push = (kind: TokenKind, text: string, pos: number, value?: number | string) => |
| 73 | tokens.push(value === undefined ? { kind, text, pos } : { kind, text, pos, value }); |
| 74 | |
| 75 | while (i < src.length) { |
| 76 | const c = src[i]!; |
| 77 | if (c === " " || c === "\t" || c === "\n" || c === "\r") { |
| 78 | i++; |
| 79 | continue; |
| 80 | } |
| 81 | const start = i; |
| 82 | // String literal: single quotes, '' escapes a quote. |
| 83 | if (c === "'") { |
| 84 | let out = ""; |
| 85 | i++; |
| 86 | for (;;) { |
| 87 | if (i >= src.length) throw new ExpressionSyntaxError("Unterminated string literal", src, start); |
| 88 | const ch = src[i]!; |
| 89 | if (ch === "'") { |
| 90 | if (src[i + 1] === "'") { |
| 91 | out += "'"; |
| 92 | i += 2; |
| 93 | continue; |
| 94 | } |
| 95 | i++; |
| 96 | break; |
| 97 | } |
| 98 | out += ch; |
| 99 | i++; |
| 100 | } |
| 101 | push("string", src.slice(start, i), start, out); |
| 102 | continue; |
| 103 | } |
| 104 | if (c === '"') { |
| 105 | throw new ExpressionSyntaxError("Unexpected double quote; string literals use single quotes", src, start); |
| 106 | } |
| 107 | // Numbers (a leading '-' or '+' is part of the literal, there is no unary minus). |
| 108 | if (isDigit(c) || ((c === "-" || c === "+" || c === ".") && (isDigit(src[i + 1]) || (src[i + 1] === "." && isDigit(src[i + 2]))))) { |
| 109 | const m = NUMBER_RE.exec(src.slice(i)); |
| 110 | if (!m) throw new ExpressionSyntaxError("Invalid number", src, start); |
| 111 | const text = m[0]; |
| 112 | if (isIdentPart(src[i + text.length]) && src[i + text.length] !== "-") { |
| 113 | throw new ExpressionSyntaxError(`Invalid number '${text}${src[i + text.length]}'`, src, start); |
| 114 | } |
| 115 | i += text.length; |
| 116 | push("number", text, start, parseNumberLiteral(text)); |
| 117 | continue; |
| 118 | } |
| 119 | if (isIdentStart(c)) { |
| 120 | while (isIdentPart(src[i])) i++; |
| 121 | const text = src.slice(start, i); |
| 122 | if (text === "true" || text === "false" || text === "null") push(text, text, start); |
| 123 | else if (text === "NaN") push("number", text, start, NaN); |
| 124 | else if (text === "Infinity") push("number", text, start, Infinity); |
| 125 | else push("ident", text, start); |
| 126 | continue; |
| 127 | } |
| 128 | const two = src.slice(i, i + 2); |
| 129 | if (two === "<=" || two === ">=" || two === "==" || two === "!=" || two === "&&" || two === "||") { |
| 130 | push(two, two, start); |
| 131 | i += 2; |
| 132 | continue; |
| 133 | } |
| 134 | if ("()[].,*!<>".includes(c)) { |
| 135 | push(c as TokenKind, c, start); |
| 136 | i++; |
| 137 | continue; |
| 138 | } |
| 139 | throw new ExpressionSyntaxError(`Unexpected character '${c}'`, src, start); |
| 140 | } |
| 141 | push("eof", "", src.length); |
| 142 | return tokens; |
| 143 | } |