NodeTraversal (Closure Compiler v20170521 API)

java.lang.Object
- com.google.javascript.jscomp.NodeTraversal

```
public class NodeTraversal
extends Object
```
NodeTraversal allows an iteration through the nodes in the parse tree, and facilitates the optimizations on the parse tree.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`NodeTraversal.AbstractModuleCallback` Abstract callback that knows when goog.modules (and in the future ES6 modules) are entered and exited.
`static class`	`NodeTraversal.AbstractNodeTypePruningCallback` Abstract callback to visit a pruned set of nodes.
`static class`	`NodeTraversal.AbstractPostOrderCallback` Abstract callback to visit all nodes in postorder.
`static class`	`NodeTraversal.AbstractPreOrderCallback` Abstract callback to visit all nodes in preorder.
`static class`	`NodeTraversal.AbstractScopedCallback` Abstract scoped callback to visit all nodes in postorder.
`static class`	`NodeTraversal.AbstractShallowCallback` Abstract callback to visit all nodes but not traverse into function bodies.
`static class`	`NodeTraversal.AbstractShallowStatementCallback` Abstract callback to visit all structure and statement nodes but doesn't traverse into functions or expressions.
`static interface`	`NodeTraversal.Callback` Callback for tree-based traversals
`static interface`	`NodeTraversal.FunctionCallback` Callback for passes that iterate over a list of functions
`static interface`	`NodeTraversal.ScopedCallback` Callback that also knows about scope changes

Constructor Summary

Constructors
Constructor and Description
`NodeTraversal(AbstractCompiler compiler, NodeTraversal.Callback cb, com.google.javascript.jscomp.ScopeCreator scopeCreator)` Creates a node traversal using the specified callback interface and the scope creator.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`getCharno()` Gets the current char number, or zero if it cannot be determined.
`Scope`	`getClosestHoistScope()`
`AbstractCompiler`	`getCompiler()`
`ControlFlowGraph<Node>`	`getControlFlowGraph()` Gets the control flow graph for the current JS scope.
`Node`	`getCurrentNode()` Returns the node currently being traversed.
`Node`	`getEnclosingFunction()` Examines the functions stack for the last instance of a function node.
`CompilerInput`	`getInput()` Gets the current input source.
`int`	`getLineNumber()` Gets the current line number, or zero if it cannot be determined.
`JSModule`	`getModule()` Gets the current input module.
`Scope`	`getScope()` Gets the current scope.
`Node`	`getScopeRoot()` Returns the current scope's root.
`String`	`getSourceName()` Gets the current input source name.
`TypedScope`	`getTypedScope()`
`boolean`	`inFunctionBlockScope()` Determines whether the traversal is currently in the scope of the block of a function.
`boolean`	`inGlobalHoistScope()` Determines whether the hoist scope of the current traversal is global.
`boolean`	`inGlobalScope()` Determines whether the traversal is currently in the global scope.
`boolean`	`inModuleHoistScope()` Determines whether the hoist scope of the current traversal is global.
`boolean`	`inModuleScope()` Determines whether the traversal is currently in the global scope.
`JSError`	`makeError(Node n, CheckLevel level, DiagnosticType type, String... arguments)` Creates a JSError during NodeTraversal.
`JSError`	`makeError(Node n, DiagnosticType type, String... arguments)` Creates a JSError during NodeTraversal.
`void`	`report(Node n, DiagnosticType diagnosticType, String... arguments)` Reports a diagnostic (error or warning)
`void`	`reportCodeChange()`
`void`	`reportCodeChange(Node n)`
`void`	`traverse(Node root)` Traverses a parse tree recursively.
`static void`	`traverseChangedFunctions(AbstractCompiler compiler, NodeTraversal.FunctionCallback callback)` Traversal for passes that work only on changed functions.
`static void`	`traverseEs6(AbstractCompiler compiler, Node root, NodeTraversal.Callback cb)` Traverses using the ES6SyntacticScopeCreator
`void`	`traverseFunctionOutOfBand(Node node, Scope scope)` Traverse a function out-of-band of normal traversal.
`static void`	`traverseRootsEs6(AbstractCompiler compiler, NodeTraversal.Callback cb, Node externs, Node root)`
`static void`	`traverseRootsTyped(AbstractCompiler compiler, NodeTraversal.Callback cb, Node externs, Node root)`
`static void`	`traverseTyped(AbstractCompiler compiler, Node root, NodeTraversal.Callback cb)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - NodeTraversal
```
public NodeTraversal(AbstractCompiler compiler,
                     NodeTraversal.Callback cb,
                     com.google.javascript.jscomp.ScopeCreator scopeCreator)
```
    Creates a node traversal using the specified callback interface and the scope creator.
- Method Detail
  - traverse
```
public void traverse(Node root)
```
    Traverses a parse tree recursively.
  - traverseFunctionOutOfBand
```
public void traverseFunctionOutOfBand(Node node,
                                      Scope scope)
```
    Traverse a function out-of-band of normal traversal.
    
    Parameters:
    
    node - The function node.
    
    scope - The scope the function is contained in. Does not fire enter/exit callback events for this scope.
  - getCompiler
```
public AbstractCompiler getCompiler()
```
  - getLineNumber
```
public int getLineNumber()
```
    Gets the current line number, or zero if it cannot be determined. The line number is retrieved lazily as a running time optimization.
  - getCharno
```
public int getCharno()
```
    Gets the current char number, or zero if it cannot be determined. The line number is retrieved lazily as a running time optimization.
  - getSourceName
```
public String getSourceName()
```
    Gets the current input source name.
    
    Returns:
    
    A string that may be empty, but not null
  - getInput
```
public CompilerInput getInput()
```
    Gets the current input source.
  - getModule
```
public JSModule getModule()
```
    Gets the current input module.
  - getCurrentNode
```
public Node getCurrentNode()
```
    Returns the node currently being traversed.
  - traverseChangedFunctions
```
public static void traverseChangedFunctions(AbstractCompiler compiler,
                                            NodeTraversal.FunctionCallback callback)
```
    Traversal for passes that work only on changed functions. Suppose a loopable pass P1 uses this traversal. Then, if a function doesn't change between two runs of P1, it won't look at the function the second time. (We're assuming that P1 runs to a fixpoint, o/w we may miss optimizations.)
    Most changes are reported with calls to Compiler.reportCodeChange(), which doesn't know which scope changed. We keep track of the current scope by calling Compiler.setScope inside pushScope and popScope. The automatic tracking can be wrong in rare cases when a pass changes scope w/out causing a call to pushScope or popScope. Passes that do cross-scope modifications call Compiler.reportChangeToEnclosingScope(Node n).
  - traverseEs6
```
public static void traverseEs6(AbstractCompiler compiler,
                               Node root,
                               NodeTraversal.Callback cb)
```
    Traverses using the ES6SyntacticScopeCreator
  - traverseTyped
```
public static void traverseTyped(AbstractCompiler compiler,
                                 Node root,
                                 NodeTraversal.Callback cb)
```
  - traverseRootsEs6
```
public static void traverseRootsEs6(AbstractCompiler compiler,
                                    NodeTraversal.Callback cb,
                                    Node externs,
                                    Node root)
```
  - traverseRootsTyped
```
public static void traverseRootsTyped(AbstractCompiler compiler,
                                      NodeTraversal.Callback cb,
                                      Node externs,
                                      Node root)
```
  - getEnclosingFunction
```
public Node getEnclosingFunction()
```
    Examines the functions stack for the last instance of a function node. When possible, prefer this method over NodeUtil.getEnclosingFunction() because this in general looks at less nodes.
  - getScope
```
public Scope getScope()
```
    Gets the current scope.
  - getClosestHoistScope
```
public Scope getClosestHoistScope()
```
  - getTypedScope
```
public TypedScope getTypedScope()
```
  - getControlFlowGraph
```
public ControlFlowGraph<Node> getControlFlowGraph()
```
    Gets the control flow graph for the current JS scope.
  - getScopeRoot
```
public Node getScopeRoot()
```
    Returns the current scope's root.
  - inGlobalScope
```
public boolean inGlobalScope()
```
    Determines whether the traversal is currently in the global scope. Note that this returns false in a global block scope.
  - inFunctionBlockScope
```
public boolean inFunctionBlockScope()
```
    Determines whether the traversal is currently in the scope of the block of a function.
  - inGlobalHoistScope
```
public boolean inGlobalHoistScope()
```
    Determines whether the hoist scope of the current traversal is global.
  - inModuleScope
```
public boolean inModuleScope()
```
    Determines whether the traversal is currently in the global scope. Note that this returns false in a global block scope.
  - inModuleHoistScope
```
public boolean inModuleHoistScope()
```
    Determines whether the hoist scope of the current traversal is global.
  - report
```
public void report(Node n,
                   DiagnosticType diagnosticType,
                   String... arguments)
```
    Reports a diagnostic (error or warning)
  - reportCodeChange
```
public void reportCodeChange()
```
  - reportCodeChange
```
public void reportCodeChange(Node n)
```
  - makeError
```
public JSError makeError(Node n,
                         CheckLevel level,
                         DiagnosticType type,
                         String... arguments)
```
    Creates a JSError during NodeTraversal.
    
    Parameters:
    
    n - Determines the line and char position within the source file name
    
    type - The DiagnosticType
    
    arguments - Arguments to be incorporated into the message
  - makeError
```
public JSError makeError(Node n,
                         DiagnosticType type,
                         String... arguments)
```
    Creates a JSError during NodeTraversal.
    
    Parameters:
    
    n - Determines the line and char position within the source file name
    
    type - The DiagnosticType
    
    arguments - Arguments to be incorporated into the message

Class NodeTraversal

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

NodeTraversal

Method Detail

traverse

traverseFunctionOutOfBand

getCompiler

getLineNumber

getCharno

getSourceName

getInput

getModule

getCurrentNode

traverseChangedFunctions

traverseEs6

traverseTyped

traverseRootsEs6

traverseRootsTyped

getEnclosingFunction

getScope

getClosestHoistScope

getTypedScope

getControlFlowGraph

getScopeRoot

inGlobalScope

inFunctionBlockScope

inGlobalHoistScope

inModuleScope

inModuleHoistScope

report

reportCodeChange

reportCodeChange

makeError

makeError