com.google.javascript.jscomp.lint

Class CheckUnusedLabels

java.lang.Object

com.google.javascript.jscomp.lint.CheckUnusedLabels

All Implemented Interfaces:

CompilerPass, HotSwapCompilerPass, NodeTraversal.Callback

public final class CheckUnusedLabels
extends Object
implements NodeTraversal.Callback, HotSwapCompilerPass

Check for unused labels blocks. This can help catching errors like:

   () => {a: 2}  // Returns undefined, not an Object
 

Inspired by ESLint (https://github.com/eslint/eslint/blob/master/lib/rules/no-unused-labels.js)

Field Summary

Fields

Modifier and Type	Field and Description
static DiagnosticType	UNUSED_LABEL

Constructor Summary

Constructors

Constructor and Description
CheckUnusedLabels(AbstractCompiler compiler)

Method Summary

Methods

Modifier and Type	Method and 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 pre order (before visiting its children) and decides whether this node's children should be traversed.
void	visit(NodeTraversal t, Node n, Node parent) Visits a node in postorder (after its children have been visited).

Methods inherited from class java.lang.Object

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

Field Detail

UNUSED_LABEL

public static final DiagnosticType UNUSED_LABEL

Constructor Detail

CheckUnusedLabels

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

Description copied from interface: NodeTraversal.Callback

Visits a node in pre order (before visiting its children) and decides whether this node's children should be traversed. If children are traversed, they will be visited by NodeTraversal.Callback.visit(NodeTraversal, Node, Node) in postorder.

Implementations can have side effects (e.g. modifying the parse tree).

Specified by:

shouldTraverse in interface NodeTraversal.Callback

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 have been visited). A node is visited only if all its parents should be traversed (NodeTraversal.Callback.shouldTraverse(NodeTraversal, Node, Node)).

Implementations can have side effects (e.g. modifying the parse tree).

Specified by:

visit in interface NodeTraversal.Callback