114 lines
2.6 KiB
JavaScript
114 lines
2.6 KiB
JavaScript
'use strict';
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const SyntaxError = require('./SyntaxError.cjs');
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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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const NAME_CHAR = new Uint8Array(128).map((_, idx) =>
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/[a-zA-Z0-9\-]/.test(String.fromCharCode(idx)) ? 1 : 0
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);
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class Scanner {
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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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isNameCharCode(code = this.charCode()) {
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return code < 128 && NAME_CHAR[code] === 1;
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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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skipWs() {
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this.pos = this.findWsEnd(this.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.SyntaxError(message, this.str, this.pos);
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}
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scanSpaces() {
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return this.substringToPos(this.findWsEnd(this.pos));
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}
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scanWord() {
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let end = this.pos;
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for (; end < this.str.length; end++) {
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const code = this.str.charCodeAt(end);
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if (code >= 128 || NAME_CHAR[code] === 0) {
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break;
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}
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}
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if (this.pos === end) {
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this.error('Expect a keyword');
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}
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return this.substringToPos(end);
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}
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scanNumber() {
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let end = this.pos;
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for (; end < this.str.length; end++) {
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const code = this.str.charCodeAt(end);
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if (code < 48 || code > 57) {
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break;
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}
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}
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if (this.pos === end) {
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this.error('Expect a number');
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}
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return this.substringToPos(end);
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}
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scanString() {
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const end = this.str.indexOf('\'', this.pos + 1);
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if (end === -1) {
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this.pos = this.str.length;
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this.error('Expect an apostrophe');
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}
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return this.substringToPos(end + 1);
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}
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}
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exports.Scanner = Scanner;
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