gristlabs_grist-core/app/client/models/ColumnCache.ts

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/**
* Implements a cache of values computed from the data in a Grist column.
*/
import {TableData} from 'app/client/models/TableData';
import {DocAction} from 'app/common/DocActions';
import {isBulkUpdateRecord, isUpdateRecord} from 'app/common/DocActions';
import {getSetMapValue} from 'app/common/gutil';
export class ColumnCache<T> {
private _cachedColIndexes = new Map<string, T>();
constructor(private _tableData: TableData) {
// Whenever a table action is applied, consider invalidating per-column caches.
this._tableData.tableActionEmitter.addListener(this._invalidateCache, this);
this._tableData.dataLoadedEmitter.addListener(this._clearCache, this);
}
/**
* Returns the cached value for the given column, or calculates and caches the value using the
* provided calc() function.
*/
public getValue(colId: string, calc: () => T): T {
return getSetMapValue(this._cachedColIndexes, colId, calc);
}
private _invalidateCache(action: DocAction): void {
if (isUpdateRecord(action) || isBulkUpdateRecord(action)) {
// If the update only affects existing records, only invalidate affected columns.
const colValues = action[3];
for (const colId of Object.keys(colValues)) {
this._cachedColIndexes.delete(colId);
}
} else {
// For add/delete actions and all schema changes, drop the cache entirely to be on the safe side.
this._clearCache();
}
}
private _clearCache(): void {
this._cachedColIndexes.clear();
}
}