generate-maze/dist/generate-maze.cjs.map

Maze generator using a JavaScript implementation of Eller's Algorithm, as described here: http://www.neocomputer.org/projects/eller.html

{"version":3,"file":"generate-maze.cjs","sources":["../src/generate-maze.ts"],"sourcesContent":["type Cell = {\n  x: number,\n  y: number,\n  top: boolean,\n  left: boolean,\n  bottom: boolean,\n  right: boolean,\n  set: number,\n}\n\nfunction compact<T>(array: T[]): T[] {\n  return array.filter(Boolean);\n}\nfunction difference<T>(c: T[], d: T[]): T[] {\n  return [c, d].reduce((a, b) => a.filter(c => !b.includes(c)));\n}\nfunction initial<T>(array: T[]): T[] {\n  return array.slice(0, -1);\n}\nfunction groupBy<T>(list: T[], key: string): { [key: string]: T[] } {\n  const keys = list.map(item => item[key]);\n  let dict = uniq(keys).reduce((prev, next) => {\n    return {\n      ...prev,\n      [next]: []\n    }\n  }, {});\n\n  list.forEach(item => dict[item[key]].push(item));\n\n  return dict;\n}\nfunction last<T>(array: T[]): T {\n  return array[array.length - 1];\n}\nfunction range(n: number, end = 0): number[] {\n  return end ? Array.from(Array(end - n).keys()).map(k => k + n) : Array.from(Array(n).keys());\n}\nfunction uniq<T>(array: T[]): T[] {\n  return [...new Set(array)];\n}\nfunction sampleSize<T>(array: T[], n: number, random: () => number) {\n  n = n == null ? 1 : n;\n  const length = array == null ? 0 : array.length;\n  if (!length || n < 1) {\n    return [];\n  }\n  n = n > length ? length : n;\n  let index = -1;\n  const lastIndex = length - 1;\n  const result = [...array];\n  while (++index < n) {\n    const rand = index + Math.floor(random() * (lastIndex - index + 1));\n    const value = result[rand];\n    result[rand] = result[index];\n    result[index] = value;\n  }\n  return result.slice(0, n);\n}\n\nfunction mulberry32(seed: number) {\n  return function () {\n    let t = seed += 0x6D2B79F5;\n    t = Math.imul(t ^ t >>> 15, t | 1);\n    t ^= t + Math.imul(t ^ t >>> 7, t | 61);\n    return ((t ^ t >>> 14) >>> 0) / 4294967296;\n  }\n}\n\nfunction mergeSetWith(row: Cell[], oldSet: number, newSet: number) {\n  row.forEach(box => {\n    if (box.set === oldSet) box.set = newSet;\n  });\n}\n\nfunction populateMissingSets(row: Cell[], random: () => number) {\n  const setsInUse = compact(uniq(row.map(row => row.set)));\n  const allSets = range(1, row.length + 1);\n  const availableSets = difference(allSets, setsInUse).sort(() => 0.5 - random());\n  row.filter(box => !box.set).forEach((box, i) => box.set = availableSets[i]);\n}\n\nfunction mergeRandomSetsIn(row: Cell[], random: () => number, probability = 0.5) {\n  // Randomly merge some disjoint sets\n  const allBoxesButLast = initial(row);\n  allBoxesButLast.forEach((current, x) => {\n    const next = row[x + 1];\n    const differentSets = current.set !== next.set;\n    const shouldMerge = random() <= probability;\n    if (differentSets && shouldMerge) {\n      mergeSetWith(row, next.set, current.set);\n      current.right = false;\n      next.left = false;\n    }\n  });\n}\n\nfunction addSetExits(row: Cell[], nextRow: Cell[], random: () => number) {\n  // Randomly add bottom exit for each set\n  const setsInRow = Object.values(groupBy(row, 'set'));\n  const { ceil } = Math;\n  setsInRow.forEach(set => {\n    const exits = sampleSize(set, ceil(random() * set.length), random);\n    exits.forEach(exit => {\n      if (exit) {\n        const below = nextRow[exit.x];\n        exit.bottom = false;\n        below.top = false;\n        below.set = exit.set;\n      }\n    });\n  });\n}\n\nfunction generate(width = 8, height = width, closed = true, seed = 1) {\n  const random = mulberry32(seed);\n  const maze = [];\n  const r = range(width);\n\n  // Populate maze with empty cells:\n  for (let y = 0; y < height; y += 1) {\n    const row = r.map(x => {\n      return {\n        x,\n        y,\n        top: closed || y > 0,\n        left: closed || x > 0,\n        bottom: closed || y < (height - 1),\n        right: closed || x < (width - 1)\n      };\n    });\n    maze.push(row);\n  }\n\n  // All rows except last:\n  initial(maze).forEach((row, y) => { // TODO initial temp?\n    populateMissingSets(row, random);\n    mergeRandomSetsIn(row, random);\n    addSetExits(row, maze[y + 1], random);\n  });\n\n  const lastRow = last(maze);\n  populateMissingSets(lastRow, random);\n  mergeRandomSetsIn(lastRow, random, 1);\n\n  return maze;\n}\n\nexport default generate;\n"],"names":["initial","array","slice","range","n","end","Array","from","keys","map","k","uniq","Set","populateMissingSets","row","random","setsInUse","set","filter","Boolean","availableSets","c","length","d","reduce","a","b","includes","sort","box","forEach","i","mergeRandomSetsIn","probability","current","x","next","differentSets","shouldMerge","oldSet","newSet","mergeSetWith","right","left","width","height","closed","seed","t","Math","imul","mulberry32","maze","r","y","top","bottom","push","nextRow","setsInRow","Object","values","list","key","dict","item","prev","groupBy","ceil","index","lastIndex","result","rand","floor","value","sampleSize","exit","below","addSetExits","lastRow"],"mappings":"irBAgBA,SAASA,EAAWC,GAClB,OAAOA,EAAMC,MAAM,GAAI,GAkBzB,SAASC,EAAMC,EAAWC,EAAM,GAC9B,OAAOA,EAAMC,MAAMC,KAAKD,MAAMD,EAAMD,GAAGI,QAAQC,IAAIC,GAAKA,EAAIN,GAAKE,MAAMC,KAAKD,MAAMF,GAAGI,QAEvF,SAASG,EAAQV,GACf,MAAO,IAAI,IAAIW,IAAIX,IAoCrB,SAASY,EAAoBC,EAAaC,GACxC,MAAMC,EAAoBL,EAAKG,EAAIL,IAAIK,GAAOA,EAAIG,MAjErCC,OAAOC,SAmEdC,GAjEeC,EAgELlB,EAAM,EAAGW,EAAIQ,OAAS,GAhETC,EAiEaP,EAhEnC,CAACK,EAAGE,GAAGC,OAAO,CAACC,EAAGC,IAAMD,EAAEP,OAAOG,IAAMK,EAAEC,SAASN,MAgEJO,KAAK,IAAM,GAAMb,KAjExE,IAAuBM,EAAQE,EAkE7BT,EAAII,OAAOW,IAAQA,EAAIZ,KAAKa,QAAQ,CAACD,EAAKE,IAAMF,EAAIZ,IAAMG,EAAcW,IAG1E,SAASC,EAAkBlB,EAAaC,EAAsBkB,EAAc,IAElDjC,EAAQc,GAChBgB,QAAQ,CAACI,EAASC,KAChC,MAAMC,EAAOtB,EAAIqB,EAAI,GACfE,EAAgBH,EAAQjB,MAAQmB,EAAKnB,IACrCqB,EAAcvB,KAAYkB,EAC5BI,GAAiBC,IApBzB,SAAsBxB,EAAayB,EAAgBC,GACjD1B,EAAIgB,QAAQD,IACNA,EAAIZ,MAAQsB,IAAQV,EAAIZ,IAAMuB,KAmBhCC,CAAa3B,EAAKsB,EAAKnB,IAAKiB,EAAQjB,KACpCiB,EAAQQ,OAAQ,EAChBN,EAAKO,MAAO,oBAsBlB,SAAkBC,EAAQ,EAAGC,EAASD,EAAOE,GAAS,EAAMC,EAAO,GACjE,MAAMhC,EAvDR,SAAoBgC,GAClB,kBACE,IAAIC,EAAID,GAAQ,WAGhB,OAFAC,EAAIC,KAAKC,KAAKF,EAAIA,IAAM,GAAQ,EAAJA,GAC5BA,GAAKA,EAAIC,KAAKC,KAAKF,EAAIA,IAAM,EAAO,GAAJA,KACvBA,EAAIA,IAAM,MAAQ,GAAK,YAkDnBG,CAAWJ,GACpBK,EAAO,GACPC,EAAIlD,EAAMyC,GAGhB,IAAK,IAAIU,EAAI,EAAGA,EAAIT,EAAQS,GAAK,EAAG,CAClC,MAAMxC,EAAMuC,EAAE5C,IAAI0B,IACT,CACLA,EAAAA,EACAmB,EAAAA,EACAC,IAAKT,GAAUQ,EAAI,EACnBX,KAAMG,GAAUX,EAAI,EACpBqB,OAAQV,GAAUQ,EAAKT,EAAS,EAChCH,MAAOI,GAAUX,EAAKS,EAAQ,KAGlCQ,EAAKK,KAAK3C,GAIZd,EAAQoD,GAAMtB,QAAQ,CAAChB,EAAKwC,KAC1BzC,EAAoBC,EAAKC,GACzBiB,EAAkBlB,EAAKC,GAxC3B,SAAqBD,EAAa4C,EAAiB3C,GAEjD,MAAM4C,EAAYC,OAAOC,OAhF3B,SAAoBC,EAAWC,GAE7B,IAAIC,EAAOrD,EADEmD,EAAKrD,IAAIwD,GAAQA,EAAI,MACZzC,OAAO,CAAC0C,EAAM9B,WAE7B8B,OACH9B,CAACA,GAAO,KAET,IAIH,OAFA0B,EAAKhC,QAAQmC,GAAQD,EAAKC,EAAI,KAAOR,KAAKQ,IAEnCD,EAqEyBG,CAAQrD,KAClCsD,KAAEA,GAASnB,KACjBU,EAAU7B,QAAQb,KA5DpB,SAAuBhB,EAAYG,EAAWW,GAC5CX,EAAS,MAALA,EAAY,EAAIA,EACpB,MAAMkB,EAAkB,MAATrB,EAAgB,EAAIA,EAAMqB,OACzC,IAAKA,GAAUlB,EAAI,EACjB,MAAO,GAETA,EAAIA,EAAIkB,EAASA,EAASlB,EAC1B,IAAIiE,GAAS,EACb,MAAMC,EAAYhD,EAAS,EACrBiD,EAAS,IAAItE,GACnB,OAASoE,EAAQjE,GAAG,CAClB,MAAMoE,EAAOH,EAAQpB,KAAKwB,MAAM1D,KAAYuD,EAAYD,EAAQ,IAC1DK,EAAQH,EAAOC,GACrBD,EAAOC,GAAQD,EAAOF,GACtBE,EAAOF,GAASK,EAElB,OAAOH,EAAOrE,MAAM,EAAGE,IA6CPuE,CAAW1D,EAAKmD,EAAKrD,IAAWE,EAAIK,QAASP,GACrDe,QAAQ8C,IACZ,GAAIA,EAAM,CACR,MAAMC,EAAQnB,EAAQkB,EAAKzC,GAC3ByC,EAAKpB,QAAS,EACdqB,EAAMtB,KAAM,EACZsB,EAAM5D,IAAM2D,EAAK3D,SA8BrB6D,CAAYhE,EAAKsC,EAAKE,EAAI,GAAIvC,KAGhC,MAAMgE,GA7GS9E,EA6GMmD,GA5GRnD,EAAMqB,OAAS,GAD9B,IAAiBrB,EAiHf,OAHAY,EAAoBkE,EAAShE,GAC7BiB,EAAkB+C,EAAShE,EAAQ,GAE5BqC"}