Thomas Camlong
61 lines
2.5 KiB
TypeScript
61 lines
2.5 KiB
TypeScript
// The below two types are used for a number with arbitrary length. By default the type `${number}` allows spaces which is not allowed in cron expressions.
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type Digit = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9;
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type NumberWithoutSpaces = `${Digit}${number | ""}` & `${number | ""}${Digit}`;
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// The below type is used to constrain the cron expression to only allow valid characters. This will find any invalid characters in the cron expression.
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type CronChars = `${"*" | "/" | "-" | "," | NumberWithoutSpaces}`;
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/**
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* Will return false if the TMaybeCron string contains any invalid characters.
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* Otherwise it will return true.
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*/
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type ConstrainedCronString<TMaybeCron extends string> = TMaybeCron extends ""
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? true
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: TMaybeCron extends `${CronChars}${infer Rest}`
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? ConstrainedCronString<Rest>
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: false;
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/**
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* Will return true if the TMaybeCron string is a valid cron expression.
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* Otherwise it will return false.
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*
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* It allows cron expressions with 5 or 6 parts. (Seconds are optional)
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* See https://nodecron.com/docs/
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*/
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export type ValidateCron<TMaybeCron extends string> =
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TMaybeCron extends `${infer inferedSecond} ${infer inferedMinute} ${infer inferedHour} ${infer inferedMonthDay} ${infer inferedMonth} ${infer inferedWeekDay}`
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? ConstrainedCronString<inferedSecond> extends true
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? ConstrainedCronString<inferedMinute> extends true
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? ConstrainedCronString<inferedHour> extends true
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? ConstrainedCronString<inferedMonthDay> extends true
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? ConstrainedCronString<inferedMonth> extends true
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? ConstrainedCronString<inferedWeekDay> extends true
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? true
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: false
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: false
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: false
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: false
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: false
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: false
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: TMaybeCron extends `${infer inferedMinute} ${infer inferedHour} ${infer inferedMonthDay} ${infer inferedMonth} ${infer inferedWeekDay}`
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? ConstrainedCronString<inferedMinute> extends true
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? ConstrainedCronString<inferedHour> extends true
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? ConstrainedCronString<inferedMonthDay> extends true
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? ConstrainedCronString<inferedMonth> extends true
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? ConstrainedCronString<inferedWeekDay> extends true
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? true
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: false
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: false
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: false
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: false
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: false
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: false;
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/**
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* Will return the cron expression if it is valid.
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* Otherwise it will return void (as type).
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*/
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export const checkCron = <const T extends string>(cron: T) => {
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return cron as ValidateCron<T> extends true ? T : void;
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};
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