Package com.google.javascript.jscomp

Class Es6NormalizeClasses

java.lang.Object

com.google.javascript.jscomp.Es6NormalizeClasses

All Implemented Interfaces:

CompilerPass, NodeTraversal.Callback, NodeTraversal.ScopedCallback

public final class Es6NormalizeClasses
extends Object
implements NodeTraversal.ScopedCallback, CompilerPass

Normalizes ES6 classes to a simpler form for easier optimization.

This pass handles four main transformations which are performed when needed:

1. Extracts class extends expressions into variables.
2. Extracts classes into variables.
3. Rewrites static class field initializers and static blocks into a static initialization method that is called after class definition.
4. If transpilation of FeatureSet.Feature.PUBLIC_CLASS_FIELDS is needed, rewrites public class instance fields into assignments in the constructor and removes static field declarations.

These transformations must be done before passes like Es6RewriteClass and Es6ConvertSuper, which only handle classes in simpler forms.

Method Summary

Modifier and Type	Method	Description
void	enterScope(NodeTraversal t)	Called immediately after entering a new scope.
void	exitScope(NodeTraversal t)	Called immediately before exiting a scope.
void	process(Node externs, Node root)	Process the JS with root node root.
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

Method Details

process

public void process(Node externs,
 Node root)

Description copied from interface: CompilerPass

Process the JS with root node root. Can modify the contents of each Node tree

Specified by:

process in interface CompilerPass

Parameters:

externs - Top of external JS tree

root - Top of JS tree

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

enterScope

public 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 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

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.