DoublePipeline.java 文件源码

@Override
public final DoubleStream flatMap(DoubleFunction<? extends DoubleStream> mapper) {
    Objects.requireNonNull(mapper);
    return new StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE,
                                    StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
        @Override
        Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
            return new Sink.ChainedDouble<Double>(sink) {
                @Override
                public void begin(long size) {
                    downstream.begin(-1);
                }

                @Override
                public void accept(double t) {
                    try (DoubleStream result = mapper.apply(t)) {
                        // We can do better that this too; optimize for depth=0 case and just grab spliterator and forEach it
                        if (result != null)
                            result.sequential().forEach(i -> downstream.accept(i));
                    }
                }
            };
        }
    };
}