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import { DataSource } from '@angular/cdk/collections';
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import { MatPaginator } from '@angular/material/paginator';
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import { MatSort } from '@angular/material/sort';
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import { map } from 'rxjs/operators';
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import { Observable, of as observableOf, merge } from 'rxjs';
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import { TextRegion } from '../../../../model/parts/TextRegion';
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/**
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* Data source for the SearchPaginator view. This class should
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* encapsulate all logic for fetching and manipulating the displayed data
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* (including sorting, pagination, and filtering).
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*/
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export class SearchPaginatorDataSource extends DataSource<TextRegion> {
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data: TextRegion[];
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paginator: MatPaginator;
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sort: MatSort;
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constructor() {
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super();
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}
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/**
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* Connect this data source to the table. The table will only update when
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* the returned stream emits new items.
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* @returns A stream of the items to be rendered.
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*/
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connect(): Observable<TextRegion[]> {
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// Combine everything that affects the rendered data into one update
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// stream for the data-table to consume.
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const dataMutations = [
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observableOf(this.data),
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this.paginator.page,
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this.sort.sortChange
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];
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return merge(...dataMutations).pipe(map(() => {
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return this.getPagedData(this.getSortedData([...this.data]));
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}));
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}
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/**
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* Called when the table is being destroyed. Use this function, to clean up
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* any open connections or free any held resources that were set up during connect.
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*/
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disconnect() {}
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/**
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* Paginate the data (client-side). If you're using server-side pagination,
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* this would be replaced by requesting the appropriate data from the server.
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*/
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private getPagedData(data: TextRegion[]) {
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const startIndex = this.paginator.pageIndex * this.paginator.pageSize;
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return data.splice(startIndex, this.paginator.pageSize);
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}
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/**
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* Sort the data (client-side). If you're using server-side sorting,
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* this would be replaced by requesting the appropriate data from the server.
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*/
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private getSortedData(data: TextRegion[]) {
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if (!this.sort.active || this.sort.direction === '') {
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return data;
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}
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return data.sort((a, b) => {
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return 0;
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});
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}
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}
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/** Simple sort comparator for example ID/Name columns (for client-side sorting). */
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function compare(a: string | number, b: string | number, isAsc: boolean) {
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return (a < b ? -1 : 1) * (isAsc ? 1 : -1);
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}
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