DmitrySoshnikov

// RegExp:

/x*?/

// 1. Char is main, repetition is secondary (modifier)

{
  type: 'Char',
  value: 'x',
  modifier: {

DmitrySoshnikov

Boolean.parse(string)

Specification

Parses the string argument as a boolean. The boolean returned represents the value true if the string argument is not null and is equal, ignoring case, to the string "true".

When the Boolean.parse function is called with a string argument the following steps are taken:

1. If Type(string) is not "string"

• Return false

DmitrySoshnikov

{
  "type": "RegExp",
  "body": {
    "type": "Repetition",
    "expression": {
      "type": "CharacterClass",
      "expressions": [
        {
          "type": "ClassRange",
          "from": {

DmitrySoshnikov

const regexpTree = require('regexp-tree');
 
console.log(regexpTree.parse(/a|b/i)); // RegExp AST 

DmitrySoshnikov

// by Dmitry Soshnikov

ES7:

== Lexical environment ==

  - Environment Record
  - parent (can be null)

== Environment Record ==

DmitrySoshnikov

const regexpTree = require('regexp-tree');

// Get AST.
const ast = regexpTree.parse('/[a-z]{1,}/');

// Handle nodes.
regexpTree.traverse(ast, {

  // Handle "Quantifier" node type,
  // transforming `{1,}` quantifier to `+`.

DmitrySoshnikov

const regexpTree = require('regexp-tree');

const re = regexpTree.generate({
  type: 'RegExp',
  body: {
    type: 'Char',
    value: 'a',
    kind: 'simple',
  },
  flags: 'gi',

DmitrySoshnikov

const regexpTree = require('regexp-tree');

const originalRe = /[a-zA-Z_0-9][A-Z_\da-z]*\e{1,}/;

const optimizedRe = regexpTree
  .optimize(originalRe)
  .toRegExp();

console.log(optimizedRe); // /\w+e+/

DmitrySoshnikov

const regexpTree = require('regexp-tree');

// Using new syntax.
const originalRe = '/(?<all>.)\\k<all>/s';

// For legacy engines.
const compatTranspiledRe = regexpTree
  .compatTranspile(originalRe)
  .toRegExp();

DmitrySoshnikov

/
  # A regular expression for date.

  (?<year>\d{4})-    # year part of a date
  (?<month>\d{2})-   # month part of a date
  (?<day>\d{2})      # day part of a date

/x

// Is translated into: