35 lines
1.3 KiB
TypeScript
35 lines
1.3 KiB
TypeScript
import { Type } from './type';
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declare class Case<In, Out> {
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type: Type<In>;
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fn: (x: In) => Out;
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constructor(type: Type<In>, fn: (x: In) => Out);
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}
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type InOfCase<T extends Case<any, any>> = T extends Case<infer In, any> ? In : never;
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type OutOfCase<T extends Case<any, any>> = T extends Case<any, infer Out> ? Out : never;
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export declare class CaseSwitch<Cases extends Case<any, any>> {
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cases: Cases[];
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private memoAccept;
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constructor(cases: Cases[]);
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get accept(): Type<InOfCase<Cases>>;
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run(val: InOfCase<Cases>): OutOfCase<Cases>;
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/**
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* Create a new CaseSwitch that also handles the specified case.
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*/
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when<In, Out>(type: Type<In>, fn: (v: In) => Out): CaseSwitch<Cases | Case<In, Out>>;
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}
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/**
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* Create a type switch that can be used with `match()`.
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*/
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export declare function when<In, Out>(type: Type<In>, fn: (v: In) => Out): CaseSwitch<Case<In, Out>>;
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/**
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* Match a value against a type switch created with `when()`.
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*
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* @example
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* const asString = t.match(foo,
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* t.when(t.array(t.str), xs => xs.join(' and '))
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* .when(t.str, s => s)
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* .when(t.any, x => '' + x))
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*/
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export declare function match<Cases extends Case<any, any>>(val: InOfCase<Cases>, sw: CaseSwitch<Cases>): OutOfCase<Cases>;
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export {};
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