@electric-sql/d2ts/dist/sqlite/operators/count.js

D2TS is a TypeScript implementation of Differential Dataflow.

import { StreamBuilder } from '../../d2.js';
import { DifferenceStreamWriter } from '../../graph.js';
import { ReduceOperatorSQLite } from './reduce.js';
import { SQLiteContext } from '../context.js';
export class CountOperatorSQLite extends ReduceOperatorSQLite {
    constructor(id, inputA, output, initialFrontier, db) {
        const countInner = (vals) => {
            let count = 0;
            for (const [_, diff] of vals) {
                count += diff;
            }
            return [[count, 1]];
        };
        super(id, inputA, output, countInner, initialFrontier, db);
    }
}
/**
 * Counts the number of elements by key
 * Persists state to SQLite
 *
 * @param db - Optional SQLite database (can be injected via context)
 */
export function count(db) {
    return (stream) => {
        // Get database from context if not provided explicitly
        const database = db || SQLiteContext.getDb();
        if (!database) {
            throw new Error('SQLite database is required for count operator. ' +
                'Provide it as a parameter or use withSQLite() to inject it.');
        }
        const output = new StreamBuilder(stream.graph, new DifferenceStreamWriter());
        const operator = new CountOperatorSQLite(stream.graph.getNextOperatorId(), stream.connectReader(), output.writer, stream.graph.frontier(), database);
        stream.graph.addOperator(operator);
        stream.graph.addStream(output.connectReader());
        return output;
    };
}
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