@gethue/sql-formatter/src/core/regexFactory.js

Format whitespace in a SQL query to make it more readable

import { escapeRegExp, isEmpty, sortByLengthDesc } from '../utils';

export function createOperatorRegex(multiLetterOperators) {
  return new RegExp(
    `^(${sortByLengthDesc(multiLetterOperators).map(escapeRegExp).join('|')}|.)`,
    'u'
  );
}

export function createLineCommentRegex(lineCommentTypes) {
  return new RegExp(
    `^((?:${lineCommentTypes.map((c) => escapeRegExp(c)).join('|')}).*?)(?:\r\n|\r|\n|$)`,
    'u'
  );
}

export function createReservedWordRegex(reservedWords) {
  if (reservedWords.length === 0) {
    return new RegExp(`^\b$`, 'u');
  }
  const reservedWordsPattern = sortByLengthDesc(reservedWords).join('|').replace(/ /gu, '\\s+');
  return new RegExp(`^(${reservedWordsPattern})\\b`, 'iu');
}

export function createWordRegex(specialChars = []) {
  return new RegExp(
    `^([\\p{Alphabetic}\\p{Mark}\\p{Decimal_Number}\\p{Connector_Punctuation}\\p{Join_Control}${specialChars.join(
      ''
    )}]+)`,
    'u'
  );
}

export function createStringRegex(stringTypes) {
  return new RegExp('^(' + createStringPattern(stringTypes) + ')', 'u');
}

// This enables the following string patterns:
// 1. backtick quoted string using `` to escape
// 2. square bracket quoted string (SQL Server) using ]] to escape
// 3. double quoted string using "" or \" to escape
// 4. single quoted string using '' or \' to escape
// 5. national character quoted string using N'' or N\' to escape
// 6. Unicode single-quoted string using \' to escape
// 7. Unicode double-quoted string using \" to escape
// 8. PostgreSQL dollar-quoted strings
export function createStringPattern(stringTypes) {
  const patterns = {
    '``': '((`[^`]*($|`))+)',
    '{}': '((\\{[^\\}]*($|\\}))+)',
    '[]': '((\\[[^\\]]*($|\\]))(\\][^\\]]*($|\\]))*)',
    '""': '(("[^"\\\\]*(?:\\\\.[^"\\\\]*)*("|$))+)',
    "''": "(('[^'\\\\]*(?:\\\\.[^'\\\\]*)*('|$))+)",
    "N''": "((N'[^'\\\\]*(?:\\\\.[^'\\\\]*)*('|$))+)",
    "U&''": "((U&'[^'\\\\]*(?:\\\\.[^'\\\\]*)*('|$))+)",
    'U&""': '((U&"[^"\\\\]*(?:\\\\.[^"\\\\]*)*("|$))+)',
    $$: '((?<tag>\\$\\w*\\$)[\\s\\S]*?(?:\\k<tag>|$))',
  };

  return stringTypes.map((t) => patterns[t]).join('|');
}

export function createParenRegex(parens) {
  return new RegExp('^(' + parens.map(escapeParen).join('|') + ')', 'iu');
}

function escapeParen(paren) {
  if (paren.length === 1) {
    // A single punctuation character
    return escapeRegExp(paren);
  } else {
    // longer word
    return '\\b' + paren + '\\b';
  }
}

export function createPlaceholderRegex(types, pattern) {
  if (isEmpty(types)) {
    return false;
  }
  const typesRegex = types.map(escapeRegExp).join('|');

  return new RegExp(`^((?:${typesRegex})(?:${pattern}))`, 'u');
}