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import { compose } from "../compose.ts";
type CtxLike = { evtDoneOrAborted: { postCount: number; }  };
export const distinct = <T>(    keySelector?: ((value: T) => any) | undefined,    ctxFlush?: CtxLike) => compose<    T,    {        data: T,        selectedKey: any,        currentFlushCount: number;    },    {        boxedData: [T] | null;        alreadyPostedData: Set<any>;        previousFlushCount: number    },    T>(    data => [{        data,        "selectedKey": keySelector?.(data) ?? data,        "currentFlushCount": ctxFlush?.evtDoneOrAborted.postCount ?? 0    }],    [        ({ data, selectedKey, currentFlushCount }, { alreadyPostedData, previousFlushCount }) => [{            "boxedData": (                currentFlushCount !== previousFlushCount ||                !alreadyPostedData.has(selectedKey)            ) ? [data] : null,            "alreadyPostedData": new Set([                ...(                    currentFlushCount !== previousFlushCount ?                        [] : Array.from(alreadyPostedData)                ),                selectedKey            ]),            "previousFlushCount": currentFlushCount        }],        {            "boxedData": null,            "alreadyPostedData": new Set(),            "previousFlushCount": ctxFlush?.evtDoneOrAborted.postCount ?? 0        }    ],    ({ boxedData }) => boxedData);