1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
import { isArray } from './_internals/isArray.js'
// recursively traverse the given spec object to find the highest arity functionexport function __findHighestArity(spec, max = 0){  for (const key in spec){    if (spec.hasOwnProperty(key) === false || key === 'constructor') continue
    if (typeof spec[ key ] === 'object'){      max = Math.max(max, __findHighestArity(spec[ key ]))    }
    if (typeof spec[ key ] === 'function'){      max = Math.max(max, spec[ key ].length)    }  }
  return max}
function __filterUndefined(){  const defined = []  let i = 0  const l = arguments.length  while (i < l){    if (typeof arguments[ i ] === 'undefined') break    defined[ i ] = arguments[ i ]    i++  }
  return defined}
function __applySpecWithArity(  spec, arity, cache){  const remaining = arity - cache.length
  if (remaining === 1)    return x =>      __applySpecWithArity(        spec, arity, __filterUndefined(...cache, x)      )  if (remaining === 2)    return (x, y) =>      __applySpecWithArity(        spec, arity, __filterUndefined(          ...cache, x, y        )      )  if (remaining === 3)    return (      x, y, z    ) =>      __applySpecWithArity(        spec, arity, __filterUndefined(          ...cache, x, y, z        )      )  if (remaining === 4)    return (      x, y, z, a    ) =>      __applySpecWithArity(        spec,        arity,        __filterUndefined(          ...cache, x, y, z, a        )      )  if (remaining > 4)    return (...args) =>      __applySpecWithArity(        spec, arity, __filterUndefined(...cache, ...args)      )
  // handle spec as Array  if (isArray(spec)){    const ret = []    let i = 0    const l = spec.length    for (; i < l; i++){      // handle recursive spec inside array      if (typeof spec[ i ] === 'object' || isArray(spec[ i ])){        ret[ i ] = __applySpecWithArity(          spec[ i ], arity, cache        )      }      // apply spec to the key      if (typeof spec[ i ] === 'function'){        ret[ i ] = spec[ i ](...cache)      }    }
    return ret  }
  // handle spec as Object  const ret = {}  // apply callbacks to each property in the spec object  for (const key in spec){    if (spec.hasOwnProperty(key) === false || key === 'constructor') continue
    // apply the spec recursively    if (typeof spec[ key ] === 'object'){      ret[ key ] = __applySpecWithArity(        spec[ key ], arity, cache      )      continue    }
    // apply spec to the key    if (typeof spec[ key ] === 'function'){      ret[ key ] = spec[ key ](...cache)    }  }
  return ret}
export function applySpec(spec, ...args){  // get the highest arity spec function, cache the result and pass to __applySpecWithArity  const arity = __findHighestArity(spec)
  if (arity === 0){    return () => ({})  }  const toReturn = __applySpecWithArity(    spec, arity, args  )
  return toReturn}