Package com.google.javascript.jscomp

Class NodeTraversal.AbstractCfgCallback

java.lang.Object

com.google.javascript.jscomp.NodeTraversal.AbstractCfgCallback

All Implemented Interfaces:

NodeTraversal.Callback, NodeTraversal.ScopedCallback

Direct Known Subclasses:

BranchCoverageInstrumentationCallback

Enclosing class:

NodeTraversal

public abstract static class NodeTraversal.AbstractCfgCallback
extends Object
implements NodeTraversal.ScopedCallback

An traversal base class that tracks and caches the ControlFlowGraph (CFG) during the traversal. The CFGs are constructed lazily.

Constructor Summary

Constructors

Constructor	Description
AbstractCfgCallback()

Method Summary

Modifier and Type	Method	Description
final void	enterScope(NodeTraversal t)	Called immediately after entering a new scope.
void	enterScopeWithCfg(NodeTraversal t)
final void	exitScope(NodeTraversal t)	Called immediately before exiting a scope.
void	exitScopeWithCfg(NodeTraversal t)
ControlFlowGraph<Node>	getControlFlowGraph(AbstractCompiler compiler)	Gets the control flow graph for the current JS scope.
boolean	shouldTraverse(NodeTraversal t, Node n, Node parent)	Visits a node in preorder (before its children) and decides whether the node and its children should be traversed.
void	visit(NodeTraversal t, Node n, Node parent)	Visits a node in postorder (after its children).

Methods inherited from class java.lang.Object

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

Constructor Details

AbstractCfgCallback

public AbstractCfgCallback()

Method Details

getControlFlowGraph

public ControlFlowGraph<Node> getControlFlowGraph(AbstractCompiler compiler)

Gets the control flow graph for the current JS scope.

enterScope

public final void enterScope(NodeTraversal t)

Description copied from interface: NodeTraversal.ScopedCallback

Called immediately after entering a new scope. The new scope can be accessed through t.getScope()

Specified by:

enterScope in interface NodeTraversal.ScopedCallback

exitScope

public final void exitScope(NodeTraversal t)

Description copied from interface: NodeTraversal.ScopedCallback

Called immediately before exiting a scope. The ending scope can be accessed through t.getScope()

Specified by:

exitScope in interface NodeTraversal.ScopedCallback

enterScopeWithCfg

public void enterScopeWithCfg(NodeTraversal t)

exitScopeWithCfg

public void exitScopeWithCfg(NodeTraversal t)

shouldTraverse

public boolean shouldTraverse(NodeTraversal t,
 Node n,
 Node parent)

Description copied from interface: NodeTraversal.Callback

Visits a node in preorder (before its children) and decides whether the node and its children should be traversed.

If this method returns true, the node will be visited by NodeTraversal.Callback.visit(NodeTraversal, Node, Node) in postorder and its children will be visited by both NodeTraversal.Callback.shouldTraverse(NodeTraversal, Node, Node) in preorder and by NodeTraversal.Callback.visit(NodeTraversal, Node, Node) in postorder.

If this method returns false, the node will not be visited by NodeTraversal.Callback.visit(NodeTraversal, Node, Node) and its children will neither be visited by NodeTraversal.Callback.shouldTraverse(NodeTraversal, Node, Node) nor NodeTraversal.Callback.visit(NodeTraversal, Node, Node).

Siblings are always visited left-to-right.

Implementations can have side-effects (e.g. modify the parse tree). Removing the current node is legal, but removing or reordering nodes above the current node may cause nodes to be visited twice or not at all.

Specified by:

shouldTraverse in interface NodeTraversal.Callback

Parameters:

t - The current traversal.

n - The current node.

parent - The parent of the current node.

Returns:

whether the children of this node should be visited

visit

public void visit(NodeTraversal t,
 Node n,
 Node parent)

Description copied from interface: NodeTraversal.Callback

Visits a node in postorder (after its children). A node is visited in postorder iff NodeTraversal.Callback.shouldTraverse(NodeTraversal, Node, Node) returned true for its parent and itself. In particular, the root node is never visited in postorder.

Siblings are always visited left-to-right.

Implementations can have side-effects (e.g. modify the parse tree). Removing the current node is legal, but removing or reordering nodes above the current node may cause nodes to be visited twice or not at all.

Specified by:

visit in interface NodeTraversal.Callback

Parameters:

t - The current traversal.

n - The current node.

parent - The parent of the current node.