uttori-utilities/src/parse-query-to-array.js

A set of helper utilities for Uttoti components.

const debug = require('debug')('Uttori.Utilities.parseQueryToArray');
const Operator = require('./operator');
const SqlWhereParser = require('./where-parser');

/**
 * Parse a query into an array-like structure, where each sub-array is its own group of parentheses in the query.
 *
 * @param {string} query - The SQL-like string to be parsed.
 * @returns {Array} The array AST.
 * @example <caption>toArray('SQL-LIKE-QUERY')</caption>
 * parseQueryToArray('(name = "First Last") AND (age >= (20 + 7))');
 * ➜ [
 *    [
 *      'name',
 *      Operator('=', 2, 5), // '=',
 *      'First Last',
 *    ],
 *    Operator('AND', 2, 9), // 'AND',
 *    [
 *      'age',
 *      Operator('>=', 2, 5), // '>=',
 *      [
 *        20,
 *        Operator('+', 2, 4), // '+',
 *        7,
 *      ],
 *    ],
 *  ]
 */
const parseQueryToArray = (query) => {
  debug('Query:', query);
  const parser = new SqlWhereParser();
  let expression = [];
  let tokenCount = 0;
  let lastToken;
  const expressionParentheses = [];

  parser.tokenizer.tokenize(`(${query})`, (token, surroundedBy) => {
    tokenCount++;

    switch (token) {
      case '(': {
        expressionParentheses.push(expression.length);
        break;
      }
      case ')': {
        const precedenceParenthesisIndex = expressionParentheses.pop();

        let expressionTokens = expression.splice(precedenceParenthesisIndex, expression.length);

        while (Array.isArray(expressionTokens) && expressionTokens.length === 1) {
          [expressionTokens] = expressionTokens;
        }
        expression.push(expressionTokens);
        break;
      }
      case '[': {
        expressionParentheses.push(expression.length);
        break;
      }
      case ']': {
        const precedenceParenthesisIndex = expressionParentheses.pop();

        let expressionTokens = expression.splice(precedenceParenthesisIndex, expression.length);

        while (Array.isArray(expressionTokens) && expressionTokens.length === 1) {
          [expressionTokens] = expressionTokens;
        }
        expression.push(expressionTokens);
        break;
      }
      case ',':
        break;
      default: {
        let operator = null;
        if (!surroundedBy) {
          operator = parser.getOperator(token);
          if (token === '-' && (tokenCount === 1 || (lastToken === '(' || lastToken === '[' || (lastToken && lastToken.constructor === Operator)))) {
            operator = parser.getOperator(Operator.type('unary-minus'));
          }
        }
        expression.push(operator || token);
        break;
      }
    }
    lastToken = token;
  });

  while (Array.isArray(expression) && expression.length === 1) {
    [expression] = expression;
  }

  return expression;
};

module.exports = parseQueryToArray;