ts-pattern/dist/is-matching.d.cts

The exhaustive Pattern Matching library for TypeScript.

import { Pattern, UnknownProperties } from './types/Pattern.cjs';
import * as P from './patterns.cjs';
import { WithDefault } from './types/helpers.cjs';
/**
 * This constraint allows using additional properties
 * in object patterns. See "should allow targetting unknown properties"
 * unit test in `is-matching.test.ts`.
 */
type PatternConstraint<T> = T extends readonly any[] ? P.Pattern<T> : T extends object ? P.Pattern<T> & UnknownProperties : P.Pattern<T>;
/**
 * `isMatching` takes pattern and returns a **type guard** function, cheching if a value matches this pattern.
 *
 * [Read  documentation for `isMatching` on GitHub](https://github.com/gvergnaud/ts-pattern#ismatching)
 *
 * @example
 *  const hasName = isMatching({ name: P.string })
 *
 *  declare let input: unknown
 *
 *  if (hasName(input)) {
 *    // `input` inferred as { name: string }
 *    return input.name
 *  }
 */
export declare function isMatching<const p extends Pattern<unknown>>(pattern: p): (value: unknown) => value is P.infer<p>;
/**
 * `isMatching` takes pattern and a value and checks if the value matches this pattern.
 *
 * [Read  documentation for `isMatching` on GitHub](https://github.com/gvergnaud/ts-pattern#ismatching)
 *
 * @example
 *  declare let input: unknown
 *
 *  if (isMatching({ name: P.string }, input)) {
 *    // `input` inferred as { name: string }
 *    return input.name
 *  }
 */
export declare function isMatching<const T, const P extends PatternConstraint<T>>(pattern: P, value: T): value is T & WithDefault<P.narrow<T, P>, P.infer<P>>;
export {};