query-selector-lite.js

const { ASTLite } = require('./ast-lite');

function searchForTagName(tagName, tag) {
  return tag.name === tagName;
}
function searchForId(id, tag) {
  return tag.attributes.id && tag.attributes.id.toLowerCase() === id.substring(1).toLowerCase();
}
function searchForClass(desiredClassName, tag) {
  return tag.attributes.class
    && tag.attributes.class.split(' ').some((className) => className.toLowerCase() === desiredClassName.substring(1).toLowerCase());
}

function interpretSubquery(query) {
  const operator = query[0];
  switch (operator) {
    case '.':
      return (tag) => searchForClass(query, tag);
    case '#':
      return (tag) => searchForId(query, tag);
    default:
      return (tag) => searchForTagName(query, tag);
  }
}

function createSubQueryMap(subQuery) {
  const subQueryMap = [];
  const combinators = {
    descendant: ' ',
  };
  for (const matchers of Object.values(combinators)) {

  }
}

/**
 * Query Interpret Logic:
 * Go through each character
 *  1. Determine basic selectors
 *  2. Determine Combinator
 *  3. Create a list of query actions
 *  [
 *    {
 *      combinator: null,
 *      basicSelector: '.test',
 *      nodes: []
 *    },
 *    {
 *        combinator: 'descendant',
 *        basicSelector: 'div',
 *
 *    }
 * ]
 *
 */

class Document {
  constructor(htmlString = null) {
    // Create AST from htmlString if provided
    if (htmlString) {
      this.ast = new ASTLite();
      this.ast.createAST(htmlString);
    }
  }

  async loadFile(filePath) {
    this.ast = new ASTLite();
    await this.ast.loadFile(filePath);
  }

  querySelector(query) {
    return this.querySelectorAll(query)[0];
  }

  querySelectorAll(query) {
    const subQueries = query.split(',').map((q) => q.trim());
    const tags = new Set();
    for (const subQuery of subQueries) {
      const subQueryMap = createSubQueryMap(subQuery);
      const selectorFn = interpretSubquery(subQuery);
      this.ast.getTagArray().filter(selectorFn).forEach((item) => tags.add(item));
    }
    return Array.from(tags);
  }
}

module.exports = Document;