23 lines
465 B
TypeScript
23 lines
465 B
TypeScript
interface Query<T> {
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// ...
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groupBy<K>(keySelector: (item: T) => K): Query<Grouping<K, T>>;
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// ...
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}
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interface QueryEnumerator<T> {
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// ...
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groupBy<K>(keySelector: (item: T) => K): QueryEnumerator<Grouping<K, T>>;
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// ...
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}
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interface Grouping<K, T> extends Query<T> {
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key(): K;
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}
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var q1: Query<number>;
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var q2: QueryEnumerator<number>;
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var q3: Query<number>;
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q1 = q2; // should error
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q1 = q3; // should not error
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