sucrase/dist/NameManager.mjs

Super-fast alternative to Babel for when you can target modern JS runtimes

import getIdentifierNames from "./util/getIdentifierNames";

export default class NameManager {
    __init() {this.usedNames = new Set()}

  constructor(code, tokens) {;NameManager.prototype.__init.call(this);
    this.usedNames = new Set(getIdentifierNames(code, tokens));
  }

  claimFreeName(name) {
    const newName = this.findFreeName(name);
    this.usedNames.add(newName);
    return newName;
  }

  findFreeName(name) {
    if (!this.usedNames.has(name)) {
      return name;
    }
    let suffixNum = 2;
    while (this.usedNames.has(name + suffixNum)) {
      suffixNum++;
    }
    return name + suffixNum;
  }
}