| 'use strict'; |
| |
| const SyntaxError = require('./SyntaxError.cjs'); |
| |
| const TAB = 9; |
| const N = 10; |
| const F = 12; |
| const R = 13; |
| const SPACE = 32; |
| const NAME_CHAR = new Uint8Array(128).map((_, idx) => |
| /[a-zA-Z0-9\-]/.test(String.fromCharCode(idx)) ? 1 : 0 |
| ); |
| |
| class Scanner { |
| constructor(str) { |
| this.str = str; |
| this.pos = 0; |
| } |
| |
| charCodeAt(pos) { |
| return pos < this.str.length ? this.str.charCodeAt(pos) : 0; |
| } |
| charCode() { |
| return this.charCodeAt(this.pos); |
| } |
| isNameCharCode(code = this.charCode()) { |
| return code < 128 && NAME_CHAR[code] === 1; |
| } |
| nextCharCode() { |
| return this.charCodeAt(this.pos + 1); |
| } |
| nextNonWsCode(pos) { |
| return this.charCodeAt(this.findWsEnd(pos)); |
| } |
| skipWs() { |
| this.pos = this.findWsEnd(this.pos); |
| } |
| findWsEnd(pos) { |
| for (; pos < this.str.length; pos++) { |
| const code = this.str.charCodeAt(pos); |
| if (code !== R && code !== N && code !== F && code !== SPACE && code !== TAB) { |
| break; |
| } |
| } |
| |
| return pos; |
| } |
| substringToPos(end) { |
| return this.str.substring(this.pos, this.pos = end); |
| } |
| eat(code) { |
| if (this.charCode() !== code) { |
| this.error('Expect `' + String.fromCharCode(code) + '`'); |
| } |
| |
| this.pos++; |
| } |
| peek() { |
| return this.pos < this.str.length ? this.str.charAt(this.pos++) : ''; |
| } |
| error(message) { |
| throw new SyntaxError.SyntaxError(message, this.str, this.pos); |
| } |
| |
| scanSpaces() { |
| return this.substringToPos(this.findWsEnd(this.pos)); |
| } |
| scanWord() { |
| let end = this.pos; |
| |
| for (; end < this.str.length; end++) { |
| const code = this.str.charCodeAt(end); |
| if (code >= 128 || NAME_CHAR[code] === 0) { |
| break; |
| } |
| } |
| |
| if (this.pos === end) { |
| this.error('Expect a keyword'); |
| } |
| |
| return this.substringToPos(end); |
| } |
| scanNumber() { |
| let end = this.pos; |
| |
| for (; end < this.str.length; end++) { |
| const code = this.str.charCodeAt(end); |
| |
| if (code < 48 || code > 57) { |
| break; |
| } |
| } |
| |
| if (this.pos === end) { |
| this.error('Expect a number'); |
| } |
| |
| return this.substringToPos(end); |
| } |
| scanString() { |
| const end = this.str.indexOf('\'', this.pos + 1); |
| |
| if (end === -1) { |
| this.pos = this.str.length; |
| this.error('Expect an apostrophe'); |
| } |
| |
| return this.substringToPos(end + 1); |
| } |
| } |
| |
| exports.Scanner = Scanner; |