cube-notation-normalizer

There are several number of rubik's cube related programs on npm, and many of them has their own functions to parse algorithms. Mostly their functions support only limited syntax of algorithm notation unfortunately.

This library intends to be a base for this kind of programs to support broad syntax of algorithm notation.

The syntax definition is written by and the parser is generated by PEG.js.

Install

$ npm install cube-notation-normalizer

Simple usage

const normalize = require('cube-notation-normalizer');
 
const ugly = "(rU R' U`) (r' FRF' )  ";
 
// default, human-readable format
normalize(ugly);
// => "r U R' U' r' F R F'"
 
// program-friendly format
normalize(ugly, {
  separator: '',
  useModifiers: false,
  uniformCenterMoves: 'slice'
});
// => "RMMMURRRUUURRRMFRFFF"

With the latter options, result will contain only R, U, F, L, D, B, M, E and S letters and not contain any whitespaces nor modifiers. This is highly well-formatted and will be very handy for programs. Especially, .split('') or .match(/(.)\1*/g) may be useful.

If you prefer, you also can choose x, y and z instead of M, E and S.

Supported syntax and features

Face turns, slice turns and cube rotations

// supported face letters:
normalize("R U F L D B M E S x y z");
// => "R U F L D B M E S r u f l d b x y z"

Double layer turns

// 'w' notation is normalized to lowercase
normalize("r Uw");
// => "r u"

Whitespaces and comments

normalize(`
R        (U)
R'U' // sexy move
/*
R' F R F'
*/
`);
// => "R U R' U'"

Invert

// variety of "prime"s
normalize("R' U` R´ Uʼ R’ U′ Ri");
// => "R' U' R' U' R' U' R'"
 
normalize("(R U F)'");
// => "F' U' R'"

Repetitions

normalize("R3 U18 (F D)2");
// => "R' U2 F D F D"
 
// '*' and '^' are optional
normalize("R*2 U^18 (F D)*2");
// => "R2 U2 F D F D"

Conjugates and commutators

normalize("[F: R]");
// => "F R F'"
 
normalize("[R, U]");
// => "R U R' U'"
 
normalize("[F: [R, U]]");
// => "F R U R' U' F'"

Obvious optimization

normalize("U4");
// => ""
 
normalize("U R4 U");
// => "U2"
 
normalize("R L R");
// => "R2 L"

API

normalize(algorithm[, options])

algorithm

Algorithm notation string to normalize.

options

Object with following format. All properties are optional.

{
  separator: ' ',
  useModifiers: true,
  uniformCenterMoves: false,  // false | 'rotation' | 'slice'
  invert: false
}

separator

Separator string which will be inserted between each turns. (default ' ')

useModifiers

If true, returned notation includes modifier letters ' and 2. If false, inverted turns and half turns are represented as repetition. (default true)

normalize("R' U2", { useModifiers: false });
// => "R R R U U"

uniformCenterMoves

If 'rotation' or 'slice', the turns with center moves (M, x, r, etc.) are converted and unified to rotation moves (x, y and z) or slice moves (M, E and S). (default false)

normalize("r E", { uniformCenterMoves: 'rotation' });
// => "L' x U D' y'"
 
normalize("y r", { uniformCenterMoves: 'slice' });
// => "U D' E' R M'"

Note: This center move conversion is valid for only 3x3x3 cube.

invert

If true, algorithm will be inverted. (default false)

normalize("R U R' U'", { invert: true });
// => "U R U' R'"

This returns same result as normalize("(" + alg + ")'"), but using this option will make messages of possible errors more clear, especially for error location in algorithm strings.

normalize.SyntaxError

PEG.js error class thrown from the parser.