Package com.google.javascript.jscomp

Class ControlFlowAnalysis

java.lang.Object

com.google.javascript.jscomp.ControlFlowAnalysis

All Implemented Interfaces:

NodeTraversal.Callback

public final class ControlFlowAnalysis
extends Object
implements NodeTraversal.Callback

This class computes a ControlFlowGraph for a given AST

Example usage:

 ControlFlowGraph<Node> cfg = ControlFlowAnalysis.builder()
                                  .setCompiler(compiler)
                                  .setCfgRoot(functionRoot)
                                  .setShouldIncludeEdgeAnnotations(true)
                                  .computeCfg())
 

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	ControlFlowAnalysis.Builder	Configures a ControlFlowAnalysis instance then computes the ControlFlowGraph

Method Summary

Modifier and Type	Method	Description
static ControlFlowAnalysis.Builder	builder()
static boolean	isBreakTarget(Node target, String label)	Checks if target is actually the break target of labeled continue.
static boolean	mayThrowException(Node n)	Determines if the subtree might throw an exception.
boolean	shouldTraverse(NodeTraversal nodeTraversal, 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

Method Details

builder

public static ControlFlowAnalysis.Builder builder()

shouldTraverse

public boolean shouldTraverse(NodeTraversal nodeTraversal,
 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:

nodeTraversal - 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.

isBreakTarget

public static boolean isBreakTarget(Node target,
 String label)

Checks if target is actually the break target of labeled continue. The label can be null if it is an unlabeled break.

mayThrowException

public static boolean mayThrowException(Node n)

Determines if the subtree might throw an exception.