@electric-sql/d2ts/dist/operators/concat.js

D2TS is a TypeScript implementation of Differential Dataflow.

import { DifferenceStreamWriter } from '../graph.js';
import { StreamBuilder } from '../d2.js';
import { BinaryOperator } from '../graph.js';
import { MessageType } from '../types.js';
/**
 * Operator that concatenates two input streams
 */
export class ConcatOperator extends BinaryOperator {
    run() {
        for (const message of this.inputAMessages()) {
            if (message.type === MessageType.DATA) {
                const { version, collection } = message.data;
                this.output.sendData(version, collection);
            }
            else if (message.type === MessageType.FRONTIER) {
                const frontier = message.data;
                if (!this.inputAFrontier().lessEqual(frontier)) {
                    throw new Error('Invalid frontier update');
                }
                this.setInputAFrontier(frontier);
            }
        }
        for (const message of this.inputBMessages()) {
            if (message.type === MessageType.DATA) {
                const { version, collection } = message.data;
                this.output.sendData(version, collection);
            }
            else if (message.type === MessageType.FRONTIER) {
                const frontier = message.data;
                if (!this.inputBFrontier().lessEqual(frontier)) {
                    throw new Error('Invalid frontier update');
                }
                this.setInputBFrontier(frontier);
            }
        }
        const inputFrontier = this.inputAFrontier().meet(this.inputBFrontier());
        if (!this.outputFrontier.lessEqual(inputFrontier)) {
            throw new Error('Invalid frontier state');
        }
        if (this.outputFrontier.lessThan(inputFrontier)) {
            this.outputFrontier = inputFrontier;
            this.output.sendFrontier(this.outputFrontier);
        }
    }
}
/**
 * Concatenates two input streams
 * @param other - The other stream to concatenate
 */
export function concat(other) {
    return (stream) => {
        if (stream.graph !== other.graph) {
            throw new Error('Cannot concat streams from different graphs');
        }
        const output = new StreamBuilder(stream.graph, new DifferenceStreamWriter());
        const operator = new ConcatOperator(stream.graph.getNextOperatorId(), stream.connectReader(), other.connectReader(), output.writer, stream.graph.frontier());
        stream.graph.addOperator(operator);
        stream.graph.addStream(output.connectReader());
        return output;
    };
}
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