Pipeline.PipelineVisitor (core 2.44.0 API)

All Known Implementing Classes:

Pipeline.PipelineVisitor.Defaults

Enclosing class:

Pipeline
```
@Internal
public static interface Pipeline.PipelineVisitor
```
For internal use only; no backwards-compatibility guarantees.
A Pipeline.PipelineVisitor can be passed into Pipeline.traverseTopologically(org.apache.beam.sdk.Pipeline.PipelineVisitor) to be called for each of the transforms and values in the Pipeline.

Nested Class Summary

Nested Classes
Modifier and Type	Interface	Description
`static class`	`Pipeline.PipelineVisitor.CompositeBehavior`	Control enum for indicating whether or not a traversal should process the contents of a composite transform or not.
`static class`	`Pipeline.PipelineVisitor.Defaults`	Default no-op `Pipeline.PipelineVisitor` that enters all composite transforms.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Pipeline.PipelineVisitor.CompositeBehavior`	`enterCompositeTransform(TransformHierarchy.Node node)`	Called for each composite transform after all topological predecessors have been visited but before any of its component transforms.
`void`	`enterPipeline(Pipeline p)`	Called before visiting anything values or transforms, as many uses of a visitor require access to the `Pipeline` object itself.
`void`	`leaveCompositeTransform(TransformHierarchy.Node node)`	Called for each composite transform after all of its component transforms and their outputs have been visited.
`void`	`leavePipeline(Pipeline pipeline)`	Called when all values and transforms in a `Pipeline` have been visited.
`void`	`visitPrimitiveTransform(TransformHierarchy.Node node)`	Called for each primitive transform after all of its topological predecessors and inputs have been visited.
`void`	`visitValue(PValue value, TransformHierarchy.Node producer)`	Called for each value after the transform that produced the value has been visited.

- Method Detail
  - enterPipeline
```
void enterPipeline(Pipeline p)
```
    Called before visiting anything values or transforms, as many uses of a visitor require access to the Pipeline object itself.
  - enterCompositeTransform
```
Pipeline.PipelineVisitor.CompositeBehavior enterCompositeTransform(TransformHierarchy.Node node)
```
    Called for each composite transform after all topological predecessors have been visited but before any of its component transforms.
    The return value controls whether or not child transforms are visited.
  - leaveCompositeTransform
```
void leaveCompositeTransform(TransformHierarchy.Node node)
```
    Called for each composite transform after all of its component transforms and their outputs have been visited.
  - visitPrimitiveTransform
```
void visitPrimitiveTransform(TransformHierarchy.Node node)
```
    Called for each primitive transform after all of its topological predecessors and inputs have been visited.
  - visitValue
```
void visitValue(PValue value,
                TransformHierarchy.Node producer)
```
    Called for each value after the transform that produced the value has been visited.
  - leavePipeline
```
void leavePipeline(Pipeline pipeline)
```
    Called when all values and transforms in a Pipeline have been visited.