| import { SyntaxError } from './SyntaxError.js'; |
| |
| const TAB = 9; |
| const N = 10; |
| const F = 12; |
| const R = 13; |
| const SPACE = 32; |
| |
| export class Tokenizer { |
| 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); |
| } |
| nextCharCode() { |
| return this.charCodeAt(this.pos + 1); |
| } |
| nextNonWsCode(pos) { |
| return this.charCodeAt(this.findWsEnd(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(message, this.str, this.pos); |
| } |
| }; |