Method traverse

packages/graph/src/Steps.ts:777–821

(
    source: GraphSource<any>,
    input: Iterable<TraversalPath<any, any, any>>,
    context?: QueryContext,
  )

  }

  public *traverse(
    source: GraphSource<any>,
    input: Iterable<TraversalPath<any, any, any>>,
    context?: QueryContext,
  ): IterableIterator<TraversalPath<any, any, any>> {
    const { vertexLabels, condition, stepLabels } = this.config;

    // Fetch matching vertices once for performance
    const allVertices = [
      ...(vertexLabels && vertexLabels.length > 0
        ? source.getVertices(...vertexLabels)
        : source.getVertices()),
    ];

    // Filter vertices by condition if provided
    const matchingVertices = condition
      ? allVertices.filter((vertex) => {
          // Create a temporary path to evaluate the condition
          const tempPath = new TraversalPath(undefined, vertex, stepLabels ?? []);
          return evaluateCondition(tempPath, condition, context);
        })
      : allVertices;

    // Collect all input paths (we need to iterate multiple times)
    const inputPaths = [...input];
    if (inputPaths.length === 0) {
      // If no input paths, treat like FetchVerticesStep
      for (const vertex of matchingVertices) {
        this.traversed++;
        this.emitted++;
        yield new TraversalPath(undefined, vertex, stepLabels ?? []);
      }
      return;
    }

    // For each input path, combine with each matching vertex (cross-product)
    for (const inputPath of inputPaths) {
      for (const vertex of matchingVertices) {
        this.traversed++;
        this.emitted++;
        // Chain the new vertex onto the input path
        yield inputPath.with(vertex, stepLabels ?? []);
      }
    }
  }

  public override clone(partial?: Partial<CartesianFetchStepConfig>) {
    const { config } = this;