import type { HasWidenedKey, ObjectType, ObjectWithFallbackProperty } from './internal-types.js';
type ObjectWithRequiredDefinedProperty<ObjectValue extends object, Key extends keyof ObjectValue> = ObjectValue & {
    [Property in keyof Pick<ObjectValue, Key>]-?: Exclude<ObjectValue[Property], undefined>;
};
type ObjectWithNarrowedDefinedProperty<ObjectValue extends object, Key extends PropertyKey> = ObjectValue extends unknown ? Key extends keyof ObjectValue ? ObjectWithRequiredDefinedProperty<ObjectValue, Key> : ObjectWithFallbackProperty<ObjectValue, Key> : never;
type ObjectWithDefinedProperty<Value, Key extends PropertyKey> = ObjectType<Value> extends infer ObjectValue ? [ObjectValue] extends [object] ? HasWidenedKey<Key> extends true ? ObjectValue : ObjectWithNarrowedDefinedProperty<ObjectValue & object, Key> : never : never;
type IsPropertyDefinedPredicate<Key extends PropertyKey> = <Value>(value: Value) => value is ObjectWithDefinedProperty<Value, Key>;
/**
Check whether a specific own property of a value is defined, meaning it is not `undefined`.

This is useful as a type guard in `.filter()`, where TypeScript does not automatically narrow property types. Only own (not inherited) data properties are considered.

@example
```
import {isPropertyDefined} from 'ts-extras';

type Item = {
    name: string;
    value: number | undefined;
};

const items: Item[] = [{name: 'a', value: 1}, {name: 'b', value: undefined}];

items.filter(isPropertyDefined('value'));
//=> [{name: 'a', value: 1}]
// Return type is `(Item & {value: number})[]`
```

@category Type guard
*/
export declare function isPropertyDefined<Key extends PropertyKey>(key: Key): IsPropertyDefinedPredicate<Key>;
export {};