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'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;
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