com.oracle.truffle.api.nodes

Class Node

java.lang.Object

com.oracle.truffle.api.nodes.Node

All Implemented Interfaces:

NodeInterface, Cloneable

Direct Known Subclasses:

BlockNode, DirectCallNode, ExecutableNode, ExecutionEventNode, IndirectCallNode, Library, LoopNode, ProbeNode

public abstract class Node
extends Object
implements NodeInterface, Cloneable

Abstract base class for all Truffle nodes.

Since:

0.8 or earlier

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Node.Child Marks fields that represent child nodes of this node.
static interface	Node.Children Marks array fields that are children of this node.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Node()

Method Summary

Modifier and Type	Method and Description
void	accept(NodeVisitor nodeVisitor) Invokes the NodeVisitor.visit(Node) method for this node and recursively also for all child nodes.
void	adoptChildren()
<T> T	atomic(Callable<T> closure)
void	atomic(Runnable closure)
Node	copy() Creates a shallow copy of this node.
Node	deepCopy() Creates a deep copy of this node.
Iterable<Node>	getChildren() Iterator over the children of this node.
NodeCost	getCost() Returns a rough estimate for the cost of this Node.
Map<String,Object>	getDebugProperties() Returns properties of this node interesting for debugging and can be overwritten by subclasses to add their own custom properties.
String	getDescription() Returns a user-readable description of the purpose of the Node, or "" if no description is available.
SourceSection	getEncapsulatingSourceSection() Retrieves the segment of guest language source code that is represented by this Node, if present; otherwise retrieves the segment represented by the nearest AST ancestor that has this information.
protected Lock	getLock() Returns a lock object that can be used to synchronize modifications to the AST.
Node	getParent() The current parent node of this node.
RootNode	getRootNode() Get the root node of the tree a node belongs to.
SourceSection	getSourceSection() Retrieves the segment of guest language source code that is represented by this Node.
protected <T extends Node> T	insert(T newChild) Inserts an new node into an AST that was already adopted by a parent.
protected <T extends Node> T[]	insert(T[] newChildren) Inserts new node children into an AST that was already adopted by a parent.
boolean	isAdoptable() Returns true if this node can be adopted by a parent.
boolean	isSafelyReplaceableBy(Node newNode) Checks if this node can be replaced by another node: tree structure & type.
protected <C,T extends TruffleLanguage<C>> TruffleLanguage.ContextReference<C>	lookupContextReference(Class<T> languageClass) Returns a reference that returns the current execution context associated with the given language.
protected <T extends TruffleLanguage> TruffleLanguage.LanguageReference<T>	lookupLanguageReference(Class<T> languageClass) Returns a reference that returns the current language instance.
protected void	notifyInserted(Node node) Notifies the framework about the insertion of one or more nodes during execution.
protected void	onReplace(Node newNode, CharSequence reason) Intended to be implemented by subclasses of Node to receive a notification when the node is rewritten.
<T extends Node> T	replace(T newNode) Replaces this node with another node.
<T extends Node> T	replace(T newNode, CharSequence reason) Replaces this node with another node.
protected void	reportPolymorphicSpecialize() Notifies the runtime that this node specialized to a polymorphic state.
String	toString() Converts this node to a textual representation useful for debugging.

Methods inherited from class java.lang.Object

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

Constructor Detail

Node

protected Node()

Since:

0.8 or earlier

Method Detail

getCost

public NodeCost getCost()

Returns a rough estimate for the cost of this Node. This estimate can be used by runtime systems or guest languages to implement heuristics based on Truffle ASTs. This method is intended to be overridden by subclasses. The default implementation returns the value of NodeInfo.cost() of the NodeInfo annotation declared at the subclass. If no NodeInfo annotation is declared the method returns NodeCost.MONOMORPHIC as a default value.

Since:

0.8 or earlier

getSourceSection

public SourceSection getSourceSection()

Retrieves the segment of guest language source code that is represented by this Node. The default implementation of this method returns null. If your node represents a segment of the source code, override this method and return a eagerly or lazily computed source section value. This method is not designed to be invoked on compiled code paths. May be called on any thread and without a language context being active.

Simple example implementation using a simple implementation using a field:

abstract class SimpleNode extends Node {

    private SourceSection sourceSection;

    void setSourceSection(SourceSection sourceSection) {
        this.sourceSection = sourceSection;
    }

    @Override
    public SourceSection getSourceSection() {
        return sourceSection;
    }
}

Recommended implementation computing the source section lazily from primitive fields:

abstract class RecommendedNode extends Node {

    private static final int NO_SOURCE = -1;

    private int sourceCharIndex = NO_SOURCE;
    private int sourceLength;

    public abstract Object execute(VirtualFrame frame);

    // invoked by the parser to set the source
    void setSourceSection(int charIndex, int length) {
        assert sourceCharIndex == NO_SOURCE : "source should only be set once";
        this.sourceCharIndex = charIndex;
        this.sourceLength = length;
    }

    @Override
    public final SourceSection getSourceSection() {
        if (sourceCharIndex == NO_SOURCE) {
            // AST node without source
            return null;
        }
        RootNode rootNode = getRootNode();
        if (rootNode == null) {
            // not yet adopted yet
            return null;
        }
        Source source = rootNode.getSourceSection().getSource();
        return source.createSection(sourceCharIndex, sourceLength);
    }

}

Returns:

the source code represented by this Node

Since:

0.8 or earlier

getEncapsulatingSourceSection

public SourceSection getEncapsulatingSourceSection()

Retrieves the segment of guest language source code that is represented by this Node, if present; otherwise retrieves the segment represented by the nearest AST ancestor that has this information. Can be called on any thread and without a language context.

Returns:

an approximation of the source code represented by this Node

Since:

0.8 or earlier

isAdoptable

public boolean isAdoptable()

Returns true if this node can be adopted by a parent. This method is intended to be overriden by subclasses. If nodes need to be statically shared that they must not be adoptable, because otherwise the parent reference might cause a memory leak. If a node is not adoptable then then it is guaranteed that the parent pointer remains null at all times, even if the node is tried to be adopted by a parent.

Implementations of Node.isAdoptable() are required to fold to a constant result when compiled with a constant receiver.

Since:

19.0

insert

protected final <T extends Node> T[] insert(T[] newChildren)

Inserts new node children into an AST that was already adopted by a parent. The new children need to be assigned to its children field after insert was called.

Parameters:

newChildren - the array of new children whose parent should be updated

Returns:

the array of new children

Since:

0.8 or earlier

insert

protected final <T extends Node> T insert(T newChild)

Inserts an new node into an AST that was already adopted by a parent. The new child needs to be assigned to its child field after insert was called.

Parameters:

newChild - the new child whose parent should be updated

Returns:

the new child

Since:

0.8 or earlier

notifyInserted

protected final void notifyInserted(Node node)

Notifies the framework about the insertion of one or more nodes during execution. Otherwise, the framework assumes that instrumentable nodes remain unchanged after their root node is first executed. Insertions don't need to be notified if it is known that none of the inserted nodes are instrumentable.

The provided Node and its children must be adopted in the AST before invoking this method. The caller must ensure that this method is invoked only once for a given node and its children.

Example usage:

class MyRootNode extends RootNode {

    protected MyRootNode(MyLanguage language) {
        super(language);
    }

    @Child InstrumentableLanguageNode child;

    @Override
    public Object execute(VirtualFrame frame) {
        if (child == null) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            child = insert(new InstrumentableLanguageNode());
            notifyInserted(child);
        }
        return child.execute(frame);
    }

}

Parameters:

node - the node tree that got inserted.

Since:

0.27

adoptChildren

public final void adoptChildren()

Since:

0.8 or earlier

getDebugProperties

public Map<String,Object> getDebugProperties()

Returns properties of this node interesting for debugging and can be overwritten by subclasses to add their own custom properties.

Returns:

the properties as a key/value hash map

Since:

0.8 or earlier

getParent

public final Node getParent()

The current parent node of this node.

Returns:

the parent node

Since:

0.8 or earlier

replace

public final <T extends Node> T replace(T newNode,
                                        CharSequence reason)

Replaces this node with another node. If there is a source section (see Node.getSourceSection()) associated with this node, it is transferred to the new node.

Parameters:

newNode - the new node that is the replacement

reason - a description of the reason for the replacement

Returns:

the new node

Since:

0.8 or earlier

replace

public final <T extends Node> T replace(T newNode)

Replaces this node with another node. If there is a source section (see Node.getSourceSection()) associated with this node, it is transferred to the new node.

Parameters:

newNode - the new node that is the replacement

Returns:

the new node

Since:

0.8 or earlier

isSafelyReplaceableBy

public final boolean isSafelyReplaceableBy(Node newNode)

Checks if this node can be replaced by another node: tree structure & type.

Since:

0.8 or earlier

onReplace

protected void onReplace(Node newNode,
                         CharSequence reason)

Intended to be implemented by subclasses of Node to receive a notification when the node is rewritten. This method is invoked before the actual replace has happened.

Parameters:

newNode - the replacement node

reason - the reason the replace supplied

Since:

0.8 or earlier

accept

public final void accept(NodeVisitor nodeVisitor)

Invokes the NodeVisitor.visit(Node) method for this node and recursively also for all child nodes.

Parameters:

nodeVisitor - the visitor

Since:

0.8 or earlier

getChildren

public final Iterable<Node> getChildren()

Iterator over the children of this node.

Returns:

the iterator

Since:

0.8 or earlier

copy

public Node copy()

Creates a shallow copy of this node.

Returns:

the new copy

Since:

0.8 or earlier

deepCopy

public Node deepCopy()

Creates a deep copy of this node.

Returns:

the new deep copy

Since:

0.8 or earlier

getRootNode

public final RootNode getRootNode()

Get the root node of the tree a node belongs to.

Returns:

the RootNode or null if there is none.

Since:

0.8 or earlier

reportPolymorphicSpecialize

protected final void reportPolymorphicSpecialize()

Notifies the runtime that this node specialized to a polymorphic state. This includes specializations that increase "level" of polymorphism (e.g. Adding another element to an existing inline cache). The runtime can use this information to, if allowed, create a deep copy of the RootNode hosting this node and gather context sensitive profiling feedback.

Since:

0.33

toString

public String toString()

Converts this node to a textual representation useful for debugging.

Overrides:

toString in class Object

Since:

0.8 or earlier

atomic

public final void atomic(Runnable closure)

Since:

0.8 or earlier

atomic

public final <T> T atomic(Callable<T> closure)

Since:

0.8 or earlier

getLock

protected final Lock getLock()

Returns a lock object that can be used to synchronize modifications to the AST. Don't lock if you call into foreign code with potential recursions to avoid deadlocks. Use responsibly.

Since:

0.19

getDescription

public String getDescription()

Returns a user-readable description of the purpose of the Node, or "" if no description is available. Can be called on any thread and without a language context.

Since:

0.8 or earlier

lookupLanguageReference

protected final <T extends TruffleLanguage> TruffleLanguage.LanguageReference<T> lookupLanguageReference(Class<T> languageClass)

Returns a reference that returns the current language instance. The returned language reference is intended to be cached in the currently adopted AST. If this node is adoptable then the method must be invoked after the AST was adopted otherwise an IllegalStateException is thrown. The reference lookup decides which lookup method is the best given the parent ExecutableNode or RootNode and the provided languageClass. It is recommended to use @CachedLanguage instead whenever possible. The given language class must not be null. If the given language class is not known to the current engine then an IllegalArgumentException is thrown.

Usage example:

 class ExampleNode extends Node {

     @CompilationFinal private LanguageReference reference;

     void execute() {
         if (reference == null) {
             CompilerDirectives.transferToInterpreterAndInvalidate();
             this.reference = lookupLanguageReference(MyLanguage.class);
         }
         MyLanguage language = this.reference.get();
         // use language
     }
 }

 

The current language might vary between executions if resources or code was shared between multiple contexts and the node was inserted into an AST that was not associated with this language. It is not recommended to cache the language in the AST directly.

This method is designed for partial evaluation and will reliably return a constant when called with a class literal and the number of accessed languages does not exceed the limit of 5 per root executable node. If possible the reference should be cached in the AST in order to avoid the repeated lookup of the parent executable or root node.

Since:

19.0

See Also:

@CachedContext to use the context reference in specializations or exported messages.

lookupContextReference

protected final <C,T extends TruffleLanguage<C>> TruffleLanguage.ContextReference<C> lookupContextReference(Class<T> languageClass)

Returns a reference that returns the current execution context associated with the given language. The returned context reference is intended to be cached in the currently adopted AST. If this node is adoptable then the method must be invoked after the AST was adopted otherwise an IllegalStateException is thrown. The reference lookup decides which lookup method is the best given the parent ExecutableNode or RootNode and the provided languageClass. It is recommended to use @CachedContext instead whenever possible. The given language class must not be null. If the given language class is not known to the current engine then an IllegalArgumentException is thrown.

Usage example:

 class ExampleNode extends Node {

     @CompilationFinal private ContextReference reference;

     void execute() {
         if (reference == null) {
             CompilerDirectives.transferToInterpreterAndInvalidate();
             this.reference = lookupContextReference(MyLanguage.class);
         }
         MyContext context = this.reference.get();
         // use context
     }
 }

 

The current context might vary between executions if resources or code is shared between multiple contexts. It is not recommended to cache the context in the AST directly.

This method is designed for partial evaluation and will reliably return a constant when called with a class literal and the number of accessed languages does not exceed the limit of 5 per root executable node. If possible the reference should be cached in the AST in order to avoid the repeated lookup of the parent executable or root node.

Since:

19.0

See Also:

@CachedContext to use the context reference in specializations or exported messages.