graphql.util

Interface TraverserContext<T>

Type Parameters:

T - type of tree node

All Known Implementing Classes:

DefaultTraverserContext

@PublicApi
public interface TraverserContext<T>

Traversal context. It is used as providing context for traversing, but also for returning an accumulate value. (setAccumulate(Object) There is always a "fake" root context with null node, null parent, null position. See isRootContext()

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	TraverserContext.Phase

Method Summary

Modifier and Type	Method and Description
void	changeNode(T newNode) Change the current node to the provided node.
void	deleteNode() Deletes the current node.
java.util.List<Breadcrumb<T>>	getBreadcrumbs() The exact location of this node inside the tree as a list of Breadcrumb
java.util.Map<java.lang.String,java.util.List<TraverserContext<T>>>	getChildrenContexts() In case of leave returns the children contexts, which have already been visited.
<U> U	getCurrentAccumulate() The current accumulate value used as "input" for the current step.
NodeLocation	getLocation() The location of the current node regarding to the parent node.
<U> U	getNewAccumulate() The new accumulate value, previously set by setAccumulate(Object) or getCurrentAccumulate() if setAccumulate(Object) not invoked.
TraverserContext<T>	getParentContext() Returns parent context.
T	getParentNode() The parent node.
java.util.List<T>	getParentNodes() The list of parent nodes starting from the current parent.
TraverserContext.Phase	getPhase()
<U> U	getSharedContextData() Used to share something across all TraverserContext.
<S> S	getVar(java.lang.Class<? super S> key) Obtains a context local variable
<S> S	getVarFromParents(java.lang.Class<? super S> key) Searches for a context variable starting from the parent up the hierarchy of contexts until the first variable is found.
boolean	isChanged()
boolean	isDeleted()
boolean	isParallel() If the traversing happens in parallel (multi threaded) or not.
boolean	isRootContext() Returns true for the root context, which doesn't have a node or a position.
boolean	isVisited() Informs that the current node has been already "visited"
T	originalThisNode() Returns the original, unchanged, not deleted Node.
void	setAccumulate(java.lang.Object accumulate) Sets the new accumulate value.
<S> TraverserContext<T>	setVar(java.lang.Class<? super S> key, S value) Stores a variable in the context
T	thisNode() Returns current node being visited.
java.util.Set<T>	visitedNodes() Obtains all visited nodes and values received by the TraverserVisitor.enter(graphql.util.TraverserContext) method

Method Detail

thisNode

T thisNode()

Returns current node being visited. Special cases: It is null for the root context and it is the changed node after changeNode(Object) is called. Throws Exception if the node is deleted.

Returns:

current node traverser is visiting.

Throws:

AssertException - if the current node is deleted

originalThisNode

T originalThisNode()

Returns the original, unchanged, not deleted Node.

Returns:

the original node

changeNode

void changeNode(T newNode)

Change the current node to the provided node. Only applicable in enter. Useful when the tree should be changed while traversing. Also: changing a node makes only a difference when it has different children than the current one.

Parameters:

newNode - the new Node

deleteNode

void deleteNode()

Deletes the current node.

isDeleted

boolean isDeleted()

Returns:

true if the current node is deleted (by calling deleteNode()

isChanged

boolean isChanged()

Returns:

true if the current node is changed (by calling changeNode(Object)

getParentContext

TraverserContext<T> getParentContext()

Returns parent context. Effectively organizes Context objects in a linked list so by following getParentContext() links one could obtain the current path as well as the variables getVar(java.lang.Class) stored in every parent context.

Returns:

context associated with the node parent

getParentNodes

java.util.List<T> getParentNodes()

The list of parent nodes starting from the current parent.

Returns:

list of parent nodes

getParentNode

T getParentNode()

The parent node.

Returns:

The parent node.

getBreadcrumbs

java.util.List<Breadcrumb<T>> getBreadcrumbs()

The exact location of this node inside the tree as a list of Breadcrumb

Returns:

list of breadcrumbs. the first element is the location inside the parent.

getLocation

NodeLocation getLocation()

The location of the current node regarding to the parent node.

Returns:

the position or null if this node is a root node

isVisited

boolean isVisited()

Informs that the current node has been already "visited"

Returns:

true if a node had been already visited

visitedNodes

java.util.Set<T> visitedNodes()

Obtains all visited nodes and values received by the TraverserVisitor.enter(graphql.util.TraverserContext) method

Returns:

a map containg all nodes visited and values passed when visiting nodes for the first time

getVar

<S> S getVar(java.lang.Class<? super S> key)

Obtains a context local variable

Type Parameters:

S - type of the variable

Parameters:

key - key to lookup the variable value

Returns:

a variable value or null

getVarFromParents

<S> S getVarFromParents(java.lang.Class<? super S> key)

Searches for a context variable starting from the parent up the hierarchy of contexts until the first variable is found.

Type Parameters:

S - type of the variable

Parameters:

key - key to lookup the variable value

Returns:

a variable value or null

setVar

<S> TraverserContext<T> setVar(java.lang.Class<? super S> key,
                               S value)

Stores a variable in the context

Type Parameters:

S - type of a varable

Parameters:

key - key to create bindings for the variable

value - value of variable

Returns:

this context to allow operations chaining

setAccumulate

void setAccumulate(java.lang.Object accumulate)

Sets the new accumulate value. Can be retrieved by getNewAccumulate()

Parameters:

accumulate - to set

getNewAccumulate

<U> U getNewAccumulate()

The new accumulate value, previously set by setAccumulate(Object) or getCurrentAccumulate() if setAccumulate(Object) not invoked.

Type Parameters:

U - and me

Returns:

the new accumulate value

getCurrentAccumulate

<U> U getCurrentAccumulate()

The current accumulate value used as "input" for the current step.

Type Parameters:

U - and me

Returns:

the current accumulate value

getSharedContextData

<U> U getSharedContextData()

Used to share something across all TraverserContext.

Type Parameters:

U - and me

Returns:

contextData

isRootContext

boolean isRootContext()

Returns true for the root context, which doesn't have a node or a position.

Returns:

true for the root context, otherwise false

getChildrenContexts

java.util.Map<java.lang.String,java.util.List<TraverserContext<T>>> getChildrenContexts()

In case of leave returns the children contexts, which have already been visited.

Returns:

the children contexts. If the childs are a simple list the key is null.

getPhase

TraverserContext.Phase getPhase()

Returns:

the phase in which the node visits currently happens (Enter,Leave or BackRef)

isParallel

boolean isParallel()

If the traversing happens in parallel (multi threaded) or not.

Returns: