Damn

search_engine.js

/**
 * @example
 * new SearchEngine(lines, { subfield: 'conditions' }).execute('key:value')
 */
class SearchEngine {
  constructor(data, options = {}) {
    this.data = data;
    this.options = options;
  }

  parseString(query_rest, stop_chars = ' :') {
    let stop = false, escape = false, quote = false, string = '';
    while (stop === false && query_rest.length > 0) {
      const char = query_rest[0];
      query_rest = query_rest.slice(1, query_rest.length);
      if (string.length === 0 && char === ' ') { // strip space before
        // pass
      } else if (escape === true) { // if escape, force the char
        string += char;
        escape = false;
      } else if (quote && char === '"') { // if ending the last quote
        quote = false;
      } else if (!quote && char === '"') { // if starting a new quote
        quote = true;
      } else if (quote) { // if current quote active, accept every char
        string += char;
      } else if (stop_chars.indexOf(char) > -1) { // if we must stop the string
        stop = true;
      } else {
        string += char;
      }
    }
    return { query_rest, output: string };
  }


  parseQuery(query_rest = '') {
    const parsed = [];
    while (query_rest.length > 0) {
      const key = this.parseString(query_rest);
      const value = this.parseString(key.query_rest);
      parsed.push([key.output, value.output]);
      query_rest = value.query_rest;
    }
    return parsed;
  }

  execute(query) {
    // const parsed_search = query.split(' ').map(e => e.split(':')); // [ [ k, v], [ k, v ] ]
    const parsed_search = this.parseQuery(query);
    return this.data.filter((line) => {
      try {
        return this.privateExecuteOnLine(parsed_search, line);
      } catch (err) {
        console.log(err, line.conditions, parsed_search);
      }
      return false;
    });
  }

  /**
   * The line may be:
   * a string "..."
   * an array of object [ { ... }, ...]
   * an object { ... }
   *
   * Each type of line has its own search implementation
   *
   */
  privateExecuteOnLine(parsed_search, line) {
    const effective_line = this.options.subfield ? line[this.options.subfield] : line;
    if (effective_line instanceof String) {
      return parsed_search.reduce((b, p) => b && effective_line.indexOf(p), true);
    } else if (effective_line instanceof Array && effective_line[0] instanceof Object) {
      return parsed_search.reduce((b, p) => b && effective_line.find(cond => cond[p[0]] && cond[p[0]].indexOf(p[1]) > -1), true);
    } else if (effective_line instanceof Object) {
      return parsed_search.reduce((b, p) => b && effective_line[p[0]] && effective_line[p[0]].indexOf(p[1]) > -1, true);
    }
    return false;
  }
}

module.exports = SearchEngine;