maze generation in terminal

maze.js

'use strict'

const readline = require('readline')

const NORTH = 0b1000
const SOUTH = 0b0100
const EAST  = 0b0010
const WEST  = 0b0001
const ALL   = 0b1111

const flip = dir =>
  [NORTH + SOUTH, EAST + WEST].reduce((memo, mask) =>
    memo || mask & dir && ~(mask & dir) & ALL & mask
  , null)

// javascript: y u no have match expression?!
const glyph = value => {
  switch (value) {
    case NORTH + SOUTH + EAST + WEST: return '\u254B'
    case NORTH + SOUTH + EAST: return '\u2523'
    case NORTH + SOUTH + WEST: return '\u252B'
    case NORTH + SOUTH: return '\u2503'
    case NORTH + EAST + WEST: return '\u253B'
    case NORTH + EAST: return '\u2517'
    case NORTH + WEST: return '\u251B'
    case NORTH: return '\u2579'
    case SOUTH + EAST + WEST: return '\u2533'
    case SOUTH + EAST: return '\u250F'
    case SOUTH + WEST: return '\u2513'
    case SOUTH: return '\u257B'
    case EAST + WEST: return '\u2501'
    case EAST: return '\u257A'
    case WEST: return '\u2578'
  }
}

const nodes = generate(30, 50)

print(30, 50)

function generate (rows, cols) {

  const nodes = {}
  const startX = parseInt(Math.random() * cols)
  const startY = parseInt(Math.random() * rows)

  for (let x = 0; x < cols; x++ ) {
    for (let y = 0; y < rows; y++) {
      nodes[`${x},${y}`] = {x, y, parent: null, dirs: ALL, walls: ALL}
    }
  }

  const start = nodes[`${startX},${startY}`]

  start.parent = start

  let last = null

  while (last != start) {
    last = link(last || start, rows, cols)
  }

  return nodes

  function link (node, rows, cols) {

    // While there are directions still unexplored
    while (node.dirs) {

      let x = node.x
      let y = node.y

      // Randomly pick one direction
      const dir = 1 <<  Math.random() * 4

      // If it has already been explored - try again
      if (~node.dirs & dir) { continue }

      // Mark direction as explored
      node.dirs &= ~dir

      // If it's not possible to go that direction - try again
      if (dir === NORTH && node.y === 0) { continue }
      if (dir === SOUTH && node.y + 1 >= rows) { continue }
      if (dir === EAST && node.x + 1 >= cols) { continue }
      if (dir === WEST && node.x === 0) { continue }

      // Increment for the given direction
      switch (dir) {
        case EAST: x = node.x + 1; break
        case SOUTH: y = node.y + 1; break
        case WEST: x = node.x - 1; break
        case NORTH: y = node.y - 1; break
      }

      // Get destination node
      const flipped = flip(dir)
      const dest = nodes[`${x},${y}`]

      // Make sure that destination node is not a wall
      // If destination is a linked node already - abort
      // otherwise adopt nodes & tear down those walls.
      if (
        node.walls & dir &&
        dest.walls & flipped &&
        dest.parent === null
      ) {

        dest.parent = node
        node.walls &= ~dir
        dest.walls &= ~flipped
        return dest

      }
    }

    return node.parent
  }


}

function print (rows, cols) {
  process.stderr.write('\x1B[2J')

  for (let x = 0; x <= cols; x += 1 ) {
    for (let y = 0; y <= rows; y += 1) {

      const top_left = nodes[`${x - 1},${y - 1}`]
      const top_right = nodes[`${x},${y - 1}`]
      const bottom_left = nodes[`${x - 1},${y}`]
      const bottom_right = nodes[`${x},${y}`]

      let glyph1 = 0

      if (top_left && top_left.walls & EAST && (top_right && top_right.walls & WEST)) { glyph1 |= NORTH }
      if (bottom_left && bottom_left.walls & EAST && (bottom_right && bottom_right.walls & WEST)) { glyph1 |= SOUTH }
      if (top_right && top_right.walls & SOUTH && (bottom_right && bottom_right.walls & NORTH)) { glyph1 |= EAST }
      if (top_left && top_left.walls & SOUTH && (bottom_left && bottom_left.walls & NORTH)) { glyph1 |= WEST }

      // if corners or edges, show a wall
      if (!top_left && !bottom_left && !bottom_right) { glyph1 |= NORTH + EAST }
      else if (!top_left && !top_right && !bottom_left) { glyph1 |= SOUTH + EAST }
      else if (!top_left && !top_right && !bottom_right) { glyph1 |= SOUTH + WEST }
      else if (!top_right && !bottom_left && !bottom_left) { glyph1 |= NORTH + WEST }
      else if (!top_right && !top_left || !bottom_left && !bottom_right) { glyph1 |= EAST + WEST }
      else if (!top_left && !bottom_left || !top_right && !bottom_right) { glyph1 |= NORTH + SOUTH }

      readline.cursorTo(process.stderr, x, y)
      process.stderr.write(glyph(glyph1))
    }
  }

  readline.cursorTo(process.stderr, cols, rows + 1)
  process.stderr.write('')

}

output.md

$ node maze.js

┏━┳━┳━┳━┳━━┳━━━┳━━┳━━┳━━┳━━━━━┳━┳━━━━━━━┳━━━━┳━━┳━┓
┃╺┛╻┃╻┃╻┃╻╻┃╺━┓┃╺━┫╺┓┣╸╻┗━━┳╸╻┃╻┗┳━━━━━┓┃╻┏┳╸┃╺┓╹╻┃
┃╺━┫┃┃╹┃╹┃┃┗┳╸┃┣━┓┣╸┃┃┏┻━┳╸┃╺┫┃┣┓┃╺┳━━╸┃╹┃┃╹┏┻┓┣━┛┃
┣╸┏┛┃┣┳┻━┫┣┓┃┏┫╹╻╹┃┏┫┃┃┏╸┃┏┻╸┃╹┃┃┗┓┗━━┓┗━┛┃╺┛╻┗┛┏╸┃
┃┏┫╻┃┃┃╺┓╹┃┃╹┃┃┏┻━┛┃┃╹┃┃╺┛┃┏━┻━┫┗┓┃╺━┓┣━━━┻━┳┻┳━┛┏┫
┃┃┃┗┛┃┗┓┣┳┛┗━┛╹┃┏━━┛┗━┫┗┳━┛┃╺━━┫╻╹┃┏━┛┃╺━━━━┛╻╹┏━┛┃
┃┃┗━━┛╻┃┃╹╺┳━━━┫┃┏━━┓╺┻╸┣━╸┃┏━┓╹┣━┻┛┏━┛┏━━━┳━╋━┛╺┓┃
┃┃╺┓╺━┻┫┗━┓┗┳━╸┃┗┛┏┓┣━━┓╹┏━┫┣╸┗━┫╺┳━┫┏━┛┏╸┏┛╻╹┏━┓┗┫
┃┃┏┻━┓╻┗━┓┗┓╹╻┏┻━━┛┃┃┏╸┣━┛╻┃╹┏━┓┗┓┃╻┃┃╺━┫╺┫╺┻┳┛╻┣╸┃
┃┗┛┏┓┣┻┓╺┻┓┗┳┻┫╺┳╸╻┃┃┃╺┛┏━┫┗━┛╻┗┓╹┃┃┃┗┳┓┗┓┗━┓┃┏┛┃╺┫
┣━┳┛╹┃╻┣━┓┗┓╹╻╹┏┛┏┻┛┃┣━━┛╻┗━┳━┻┓┣━┛┗┻┓┃┗╸┗┳╸┃┃┃┏┻╸┃
┃┏┛┏━┫┃╹╻┗╸┗━╋━┛╻┃╺┓┃┗━╸┏┻╸┏┛┏╸╹┣━━┓╺┫┣━┳╸┃╺┫┗┛┃┏╸┃
┃┃┏┛╻┃┣━┛┏━┓┏┛┏━┛┣┓┗┻╸┏━┻┓┏┫╺┻┳━┫┏╸┃╻┃╹╻┗┳┻┓┣━╸┃┗┓┃
┃╹┃╺┫╹┣━┓┃╻┗┛┏┫┏━┛┗━┳━┛┏╸┃╹┣━┓┗┓╹┃╺┫┃┗━╋╸┃╻╹┃╺━┻┓┃┃
┃╺┻┓┃┏┛╻┗┛┣━━┛╹┗┓╻┏╸┃┏━┛╺┻━┛╻╹┏┻━┻┓┣┻╸┏┛┏┛┃┏┻━━╸┃┗┫
┣┳╸┃┣┛┏┻┓┏┻┳━━━┓┗┫┣━┛┣━┓┏━┓┏┻━┛╻╺━┛┃┏━┫┏┫╻┃┃╺┳━━┻╸┃
┃┃┏┛┃┏┫╻╹┃╻╹┏━┓┣┓╹┃┏━┫╻┗┫╻┗┫┏━━╋━━━┫╹╻┃┃╹┃┗┻┓┃┏━┳╸┃
┃┃╹╻┃┃╹┗┳┛┣━┛┏┛┃┗╸┃╹╻┃┣┓╹┣╸┃┃╺━┫┏╸┏┛╺┫┃┗━┻┓╺┛┃┃╺┛┏┫
┃┗━┫┃┗━━┫╺┻━╸┃┏┛╺━╋━┫┃╹┣━┛┏┛┣━╸┃┃╺┛╺┳┛┗┳━╸┣━━┫┃╺━┛┃
┃╻┏┛┣━━╸┣━━┳┓┃┃┏━┓╹╻┃┗┓┃╻┏┛┏┫╺━┛┣━┳━┛┏━┫╺━┫┏╸╹┣━┳╸┃
┃┃┃┏┛┏┳╸┃╻╻╹┃┃┗┫╻┗━┫┃╺┫┃┗┛┏┛┃╺┳┳┻╸┃╺━┛╻┗┳╸┃┗┳━┛╺┫╺┫
┃┃┃┃╺┫┃┏┛┃┃┏┛┣╸┃┗┳┓┣┻┓╹┣━━┻╸┣╸┃╹╻┏┻━━┳┻┓┃╺┫╻┃┏━┓┣╸┃
┃┃┃┣╸┃╹┃╺┫┃┃╺┫╺╋╸┃┃╹╻┗━┻╸╻┏━┫┏┛┏┛┃╺┓╺┫╻┃┗╸┣┛┣┛╻┃┃╺┫
┃┃┃┃╺╋━╋╸┃┃┗┓┗┓╹┏┛┗━┻━┳╸╻┣┛╻┃┗┓┃╺┻╸┣┓╹┃┣━━┛╻┃┏┛┃┗╸┃
┃┗┛┣┓╹╻╹┏┛┃┏┻╸┣━┻┓╻╺━┓┃╺╋┛┏┫┗╸┃┣━━━┛┗━┫╹┏┓╻┣┛┃╺╋━━┫
┃╺┳┛┣┳┻━┫╺╋┛┏━┛╻╻┗┻━┓┣┻┓┃╺┫┗┳━┫┣╸┏━┳━╸┗━┛┃┗┛┏┻┓┃╺┓┃
┣╸┃╻┃╹┏╸┣┓┃╺┻━━┫┣┳━┓┃╹╻┃┗┓┃╻╹╻╹╹╻┃╻┗┳━┳━┓┗━┳┛╻┃┃┏┛┃
┃╺┛┃┗━┛╻┃┃┗┳━━┓╹┃┃╻╹┣━┛┃╻┃┣┻━┻━┳┻┛┣┓╹╻╹╻┗┳━┫┏┛┃╹┃╻┃
┣━┳┻━━━┫┃┗┓┃┏╸┣━┛┃┗┳┛┏╸┃┃┃╹┏┳━┓╹┏━┛┗┳┻━┻┓╹╻┃┗┓┃╺┫┃┃
┃╻╹╻╺━━┛┗╸┃╹┃╺┛╻╺┻╸┗╸┃╺┫┗┻━┛╹╻┗━┛╺┓╺┛╺┓╺┻━┛┗╸┃┗━┛┃┃
┗┻━┻━━━━━━┻━┻━━┻━━━━━┻━┻━━━━━┻━━━━┻━━━┻━━━━━━┻━━━┻┛
$