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52 lines
1.2 KiB
52 lines
1.2 KiB
import { SyntaxError } from './SyntaxError.js'; |
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const TAB = 9; |
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const N = 10; |
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const F = 12; |
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const R = 13; |
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const SPACE = 32; |
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export class Tokenizer { |
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constructor(str) { |
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this.str = str; |
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this.pos = 0; |
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} |
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charCodeAt(pos) { |
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return pos < this.str.length ? this.str.charCodeAt(pos) : 0; |
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} |
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charCode() { |
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return this.charCodeAt(this.pos); |
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} |
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nextCharCode() { |
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return this.charCodeAt(this.pos + 1); |
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} |
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nextNonWsCode(pos) { |
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return this.charCodeAt(this.findWsEnd(pos)); |
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} |
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findWsEnd(pos) { |
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for (; pos < this.str.length; pos++) { |
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const code = this.str.charCodeAt(pos); |
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if (code !== R && code !== N && code !== F && code !== SPACE && code !== TAB) { |
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break; |
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} |
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} |
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return pos; |
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} |
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substringToPos(end) { |
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return this.str.substring(this.pos, this.pos = end); |
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} |
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eat(code) { |
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if (this.charCode() !== code) { |
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this.error('Expect `' + String.fromCharCode(code) + '`'); |
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} |
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this.pos++; |
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} |
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peek() { |
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return this.pos < this.str.length ? this.str.charAt(this.pos++) : ''; |
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} |
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error(message) { |
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throw new SyntaxError(message, this.str, this.pos); |
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} |
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};
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