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import type { CreateSelectorOptions, UnknownMemoizer } from '../types'
/**
* Runs a stability check to ensure the input selector results remain stable
* when provided with the same arguments. This function is designed to detect
* changes in the output of input selectors, which can impact the performance of memoized selectors.
*
* @param inputSelectorResultsObject - An object containing two arrays: `inputSelectorResults` and `inputSelectorResultsCopy`, representing the results of input selectors.
* @param options - Options object consisting of a `memoize` function and a `memoizeOptions` object.
* @param inputSelectorArgs - List of arguments being passed to the input selectors.
*
* @see {@link https://reselect.js.org/api/development-only-stability-checks/#inputstabilitycheck `inputStabilityCheck`}
*
* @since 5.0.0
* @internal
*/
export const runInputStabilityCheck = (
inputSelectorResultsObject: {
inputSelectorResults: unknown[]
inputSelectorResultsCopy: unknown[]
},
options: Required<
Pick<
CreateSelectorOptions<UnknownMemoizer, UnknownMemoizer>,
'memoize' | 'memoizeOptions'
>
>,
inputSelectorArgs: unknown[] | IArguments
) => {
const { memoize, memoizeOptions } = options
const { inputSelectorResults, inputSelectorResultsCopy } =
inputSelectorResultsObject
const createAnEmptyObject = memoize(() => ({}), ...memoizeOptions)
// if the memoize method thinks the parameters are equal, these *should* be the same reference
const areInputSelectorResultsEqual =
createAnEmptyObject.apply(null, inputSelectorResults) ===
createAnEmptyObject.apply(null, inputSelectorResultsCopy)
if (!areInputSelectorResultsEqual) {
let stack: string | undefined = undefined
try {
throw new Error()
} catch (e) {
// eslint-disable-next-line @typescript-eslint/no-extra-semi, no-extra-semi
;({ stack } = e as Error)
}
console.warn(
'An input selector returned a different result when passed same arguments.' +
'\nThis means your output selector will likely run more frequently than intended.' +
'\nAvoid returning a new reference inside your input selector, e.g.' +
'\n`createSelector([state => state.todos.map(todo => todo.id)], todoIds => todoIds.length)`',
{
arguments: inputSelectorArgs,
firstInputs: inputSelectorResults,
secondInputs: inputSelectorResultsCopy,
stack
}
)
}
}
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