org.springframework.cloud.dataflow.core.dsl

Class TaskVisitor

java.lang.Object

org.springframework.cloud.dataflow.core.dsl.TaskVisitor

Direct Known Subclasses:

GraphGeneratorVisitor, TaskValidatorVisitor

public abstract class TaskVisitor
extends Object

Basic visitor pattern for a parsed task. Provide a concrete implementation to participate in the visit and pass it to a parsed TaskNode. A simple task only has one sequence, for example: appA && appB && appC. In this situation preVisit(int) and postVisit(int) will only be called with 0. A more complex situation would be:

 
 appA && appB 0->:foo *->appC
 foo: appD && appE
 
 

This includes two sequences - as in two separate definitions. The primary definition references other definitions where it would be too messy to inline them. In this case preVisit(int) would be called for both 0 and 1.

Author:

Andy Clement

Constructor Summary

Constructors

Constructor and Description
TaskVisitor()

Method Summary

Modifier and Type	Method and Description
void	endVisit() The last call made to a visitor.
void	postVisit(FlowNode flow)
void	postVisit(SplitNode split)
void	postVisit(TaskAppNode taskApp)
void	postVisit(TransitionNode transition)
void	postVisitSequence(LabelledTaskNode firstNode, int sequenceNumber)
boolean	preVisit(FlowNode flow)
boolean	preVisit(SplitNode split)
boolean	preVisit(TaskAppNode taskApp) This preVisit/visit/postVisit sequence for taskApp is not invoked for inlined references to apps in transitions, for example: appA 0->:foo 1->appB.
boolean	preVisit(TransitionNode transition) After visit(TaskAppNode) and before postVisit(TaskAppNode) the transitions (if there are any) are visited for that task app.
boolean	preVisitSequence(LabelledTaskNode firstNode, int sequenceNumber)
void	startVisit(String taskName, String taskDsl) The first call made to a visitor.
void	visit(FlowNode flow)
void	visit(SplitNode split)
void	visit(TaskAppNode taskApp)
void	visit(TransitionNode transition)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TaskVisitor

public TaskVisitor()

Method Detail

startVisit

public void startVisit(String taskName,
                       String taskDsl)

The first call made to a visitor.

Parameters:

taskName - the name of the task definition

taskDsl - the textual definition of the AST being visited

endVisit

public void endVisit()

The last call made to a visitor.

preVisitSequence

public boolean preVisitSequence(LabelledTaskNode firstNode,
                                int sequenceNumber)

Parameters:

firstNode - the first node in the sequence

sequenceNumber - the sequence number, where the primary sequence is 0

Returns:

false to skip visiting the specified sequence

postVisitSequence

public void postVisitSequence(LabelledTaskNode firstNode,
                              int sequenceNumber)

preVisit

public boolean preVisit(FlowNode flow)

Parameters:

flow - the flow which represents things to execute in sequence

Returns:

false to skip visiting this flow

visit

public void visit(FlowNode flow)

postVisit

public void postVisit(FlowNode flow)

preVisit

public boolean preVisit(SplitNode split)

Parameters:

split - the split which represents things to execute in parallel

Returns:

false to skip visiting this split

visit

public void visit(SplitNode split)

postVisit

public void postVisit(SplitNode split)

preVisit

public boolean preVisit(TaskAppNode taskApp)

This preVisit/visit/postVisit sequence for taskApp is not invoked for inlined references to apps in transitions, for example: appA 0->:foo 1->appB. The reference to appB would be seen in the transition visit below.

Parameters:

taskApp - the use of a task app in a task dsl

Returns:

false to skip visiting this taskApp

visit

public void visit(TaskAppNode taskApp)

postVisit

public void postVisit(TaskAppNode taskApp)

preVisit

public boolean preVisit(TransitionNode transition)

After visit(TaskAppNode) and before postVisit(TaskAppNode) the transitions (if there are any) are visited for that task app.

Parameters:

transition - the transition

Returns:

false to skip visiting this transition

visit

public void visit(TransitionNode transition)

postVisit

public void postVisit(TransitionNode transition)