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try {
return new Function('return 1')() === 1
} catch (err) {
return false
}
})()
/**
* 计算多个数组的笛卡尔积。
*
* @param arr 数组内容
* @example
* ```typescript
* cartesianProduct([
* ['a', 'b'],
* [1, 2],
* ])
* // => [['a', 1], ['a', 2], ['b', 1], ['b', 2]]
* ```
*/
export function cartesianProduct<T>(arr: [T[]]): [T][]
export function cartesianProduct<T, U>(arr: [T[], U[]]): [T, U][]
export function cartesianProduct<T, U, V>(arr: [T[], U[], V[]]): [T, U, V][]
export function cartesianProduct<T, U, V, W>(
arr: [T[], U[], V[], W[]],
): [T, U, V, W][]
export function cartesianProduct<T, U, V, W, X>(
arr: [T[], U[], V[], W[], X[]],
): [T, U, V, W, X][]
export function cartesianProduct<T, U, V, W, X, Y>(
arr: [T[], U[], V[], W[], X[], Y[]],
): [T, U, V, W, X, Y][]
export function cartesianProduct<T, U, V, W, X, Y, Z>(
arr: [T[], U[], V[], W[], X[], Y[], Z[]],
): [T, U, V, W, X, Y, Z][]
export function cartesianProduct(arr: any[][]): any[][]
export function cartesianProduct(arr: any[][]): any[][] {
if (!Array.isArray(arr)) {
throw new Error('cartesianProduct expects an array')
}
if (!arr.length) {
return []
}
if (!Array.isArray(arr[0])) {
throw new Error('set at index 0 must be an array')
}
return (
supportNewFunction && arr.length < 100
? // 在支持动态构造函数环境下，并且数组长度小于 100 时使用快速模式
cartesianProductProviders.fast
: // 否则使用通用模式，如：小程序、数组长度大于等于 100
cartesianProductProviders.universal
).run(arr)
}
const cartesianProductProviders: Record<
'universal' | 'fast',
{
run(arr: any[][]): any[][]
[K: string]: any
}
> = {
// https://github.com/angus-c/just/blob/master/packages/array-cartesian-product/index.js
universal: {
run(arr) {
// initialize our product array
let product = arr[0].map(function (v) {
return [v]
})
for (let i = 1; i < arr.length; i++) {
if (!Array.isArray(arr[i])) {
throw new Error(`set at index ${i} must be an array`)
}
product = cartesianProductProviders.universal.baseProduct(
product,
arr[i],
)
}
return product
},
baseProduct(prevProduct: any[], arr2: any[]) {
// pre allocate all our memory
const newProduct = new Array(prevProduct.length * arr2.length)
for (let i = 0; i < prevProduct.length; i++) {
for (let j = 0; j < arr2.length; j++) {
// always provide array to array.concat for consistent behavior
newProduct[i * arr2.length + j] = prevProduct[i].concat([arr2[j]])
}
}
return newProduct
},
},
// https://github.com/ehmicky/fast-cartesian/blob/main/src/main.js
fast: {
cache: Object.create(null),
run(arr) {
const loopFunc = cartesianProductProviders.fast.getLoopFunc(arr.length)
const result: any[][] = []
loopFunc(arr, result)
return result
},
getLoopFunc(length: number) {
const cachedLoopFunc = cartesianProductProviders.fast.cache[length]
if (cachedLoopFunc !== undefined) {
return cachedLoopFunc
}
const loopFunc = cartesianProductProviders.fast.mGetLoopFunc(length)
cartesianProductProviders.fast.cache[length] = loopFunc
return loopFunc
},
mGetLoopFunc(length: number) {
const prefixArr: string[] = []
const startArr: string[] = []
const middleArr: string[] = []
const endArr: string[] = []
for (let i = 0; i < length; i++) {
prefixArr.push(
`if (!Array.isArray(arrays[${i}])) { throw new Error('set at index ${i} must be an array') }`,
)
startArr.push(
`for (var i${i} = 0; i${i} < arrays[${i}].length; i${i}++) {`,
)
middleArr.push(`arrays[${i}][i${i}]`)
endArr.push(`}`)
}
const prefix = prefixArr.join('\n')
const start = startArr.join('\n')
const middle = middleArr.join(',')
const end = endArr.join('\n')
return new Function(
'arrays',
'result',
`${prefix}\n${start}\nresult.push([${middle}])\n${end}`,
)
},
},
}
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