sequelize/lib/utils/join-sql-fragments.js

Sequelize is a promise-based Node.js ORM tool for Postgres, MySQL, MariaDB, SQLite, Microsoft SQL Server, Amazon Redshift and Snowflake’s Data Cloud. It features solid transaction support, relations, eager and lazy loading, read replication and more.

'use strict';

function doesNotWantLeadingSpace(str) {
  return /^[;,)]/.test(str);
}
function doesNotWantTrailingSpace(str) {
  return /\($/.test(str);
}

/**
 * Joins an array of strings with a single space between them,
 * except for:
 * 
 * - Strings starting with ';', ',' and ')', which do not get a leading space.
 * - Strings ending with '(', which do not get a trailing space.
 * 
 * @param {string[]} parts
 * @returns {string}
 * @private
 */
function singleSpaceJoinHelper(parts) {
  return parts.reduce(({ skipNextLeadingSpace, result }, part) => {
    if (skipNextLeadingSpace || doesNotWantLeadingSpace(part)) {
      result += part.trim();
    } else {
      result += ` ${part.trim()}`;
    }
    return {
      skipNextLeadingSpace: doesNotWantTrailingSpace(part),
      result
    };
  }, {
    skipNextLeadingSpace: true,
    result: ''
  }).result;
}

/**
 * Joins an array with a single space, auto trimming when needed.
 * 
 * Certain elements do not get leading/trailing spaces.
 * 
 * @param {any[]} array The array to be joined. Falsy values are skipped. If an
 * element is another array, this function will be called recursively on that array.
 * Otherwise, if a non-string, non-falsy value is present, a TypeError will be thrown.
 * 
 * @returns {string} The joined string.
 * 
 * @private
 */
function joinSQLFragments(array) {
  if (array.length === 0) return '';

  // Skip falsy fragments
  array = array.filter(x => x);

  // Resolve recursive calls
  array = array.map(fragment => {
    if (Array.isArray(fragment)) {
      return joinSQLFragments(fragment);
    }
    return fragment;
  });

  // Ensure strings
  for (const fragment of array) {
    if (fragment && typeof fragment !== 'string') {
      const error = new TypeError(`Tried to construct a SQL string with a non-string, non-falsy fragment (${fragment}).`);
      error.args = array;
      error.fragment = fragment;
      throw error;
    }
  }

  // Trim fragments
  array = array.map(x => x.trim());

  // Skip full-whitespace fragments (empty after the above trim)
  array = array.filter(x => x !== '');

  return singleSpaceJoinHelper(array);
}
exports.joinSQLFragments = joinSQLFragments;