Package com.google.javascript.jscomp

Class RewriteNullishCoalesceOperator

java.lang.Object

com.google.javascript.jscomp.RewriteNullishCoalesceOperator

All Implemented Interfaces:

CompilerPass, HotSwapCompilerPass, NodeTraversal.Callback

public final class RewriteNullishCoalesceOperator
extends java.lang.Object
implements NodeTraversal.Callback, HotSwapCompilerPass

Replaces the ES2020 `??` operator with conditional (?:).

Constructor Summary

Constructors

Constructor	Description
RewriteNullishCoalesceOperator(AbstractCompiler compiler)

Method Summary

Modifier and Type	Method	Description
void	hotSwapScript(Node scriptRoot, Node originalRoot)	Process the JS with root node root.
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 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 Detail

RewriteNullishCoalesceOperator

public RewriteNullishCoalesceOperator(AbstractCompiler compiler)

Method Detail

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

hotSwapScript

public void hotSwapScript(Node scriptRoot,
                          Node originalRoot)

Description copied from interface: HotSwapCompilerPass

Process the JS with root node root. This is supposed to be significantly faster compared to corresponding full-compiler passes.

Specified by:

hotSwapScript in interface HotSwapCompilerPass

Parameters:

scriptRoot - Root node corresponding to the file that is modified, should be of type Token.SCRIPT.

originalRoot - Root node corresponding to the original version of the file that is modified. Should be of type token.SCRIPT.

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 its children should be traversed. If the children should be traversed, they will be visited by NodeTraversal.Callback.shouldTraverse(NodeTraversal, Node, Node) in preorder and by NodeTraversal.Callback.visit(NodeTraversal, Node, Node) 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:

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. 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.