com.google.javascript.jscomp

Class NodeTraversal

java.lang.Object

com.google.javascript.jscomp.NodeTraversal

public class NodeTraversal
extends java.lang.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.provide, goog.module, and ES modules are entered and exited.
static class	NodeTraversal.AbstractPostOrderCallback Abstract callback to visit all nodes in postorder.
static interface	NodeTraversal.AbstractPostOrderCallbackInterface 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.ChangeScopeRootCallback Callback for passes that iterate over a list of change scope roots (FUNCTIONs and SCRIPTs)
static class	NodeTraversal.ExternsSkippingCallback Abstract callback to visit all non-extern nodes in postorder.
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

Modifier and Type	Method and Description
AbstractScope<?,?>	getAbstractScope() Gets the current scope.
int	getCharno() Gets the current char number, or zero if it cannot be determined.
AbstractScope<?,?>	getClosestContainerScope()
AbstractScope<?,?>	getClosestHoistScope()
Node	getClosestHoistScopeRoot()
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()
com.google.javascript.jscomp.ScopeCreator	getScopeCreator()
Node	getScopeRoot() Returns the current scope's root.
java.lang.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.
boolean	isHoistScope()
void	report(Node n, DiagnosticType diagnosticType, java.lang.String... arguments) Reports a diagnostic (error or warning)
void	reportCodeChange()
void	reportCodeChange(Node n)
static void	traverse(AbstractCompiler compiler, Node root, NodeTraversal.Callback cb) Traverses using the SyntacticScopeCreator
void	traverse(Node root) Traverses a parse tree recursively.
static void	traverseChangedFunctions(AbstractCompiler compiler, NodeTraversal.ChangeScopeRootCallback callback) Traversal for passes that work only on changed functions.
void	traverseFunctionOutOfBand(Node node, AbstractScope<?,?> scope) Traverse a function out-of-band of normal traversal.
static void	traversePostOrder(AbstractCompiler compiler, Node root, NodeTraversal.AbstractPostOrderCallbackInterface cb) Traverses in post order.
static void	traverseRoots(AbstractCompiler compiler, NodeTraversal.Callback cb, Node externs, Node root)
static void	traverseScopeRoots(AbstractCompiler compiler, Node root, java.util.List<Node> scopeNodes, NodeTraversal.Callback cb, boolean traverseNested) Traverses *just* the contents of provided scope nodes (and optionally scopes nested within them) but will fall back on traversing the entire AST from root if a null scope nodes list is provided.
static void	traverseScopeRoots(AbstractCompiler compiler, Node root, java.util.List<Node> scopeNodes, NodeTraversal.Callback cb, NodeTraversal.ChangeScopeRootCallback changeCallback, boolean traverseNested) Traverses *just* the contents of provided scope nodes (and optionally scopes nested within them) but will fall back on traversing the entire AST from root if a null scope nodes list is provided.

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.

traverse

public static void traverse(AbstractCompiler compiler,
                            Node root,
                            NodeTraversal.Callback cb)

Traverses using the SyntacticScopeCreator

traversePostOrder

public static void traversePostOrder(AbstractCompiler compiler,
                                     Node root,
                                     NodeTraversal.AbstractPostOrderCallbackInterface cb)

Traverses in post order.

traverseRoots

public static void traverseRoots(AbstractCompiler compiler,
                                 NodeTraversal.Callback cb,
                                 Node externs,
                                 Node root)

traverseScopeRoots

public static void traverseScopeRoots(AbstractCompiler compiler,
                                      @Nullable
                                      Node root,
                                      @Nullable
                                      java.util.List<Node> scopeNodes,
                                      NodeTraversal.Callback cb,
                                      boolean traverseNested)

Traverses *just* the contents of provided scope nodes (and optionally scopes nested within them) but will fall back on traversing the entire AST from root if a null scope nodes list is provided.

Parameters:

root - If scopeNodes is null, this method will just traverse 'root' instead. If scopeNodes is not null, this parameter is ignored.

traverseScopeRoots

public static void traverseScopeRoots(AbstractCompiler compiler,
                                      @Nullable
                                      Node root,
                                      @Nullable
                                      java.util.List<Node> scopeNodes,
                                      NodeTraversal.Callback cb,
                                      @Nullable
                                      NodeTraversal.ChangeScopeRootCallback changeCallback,
                                      boolean traverseNested)

Traverses *just* the contents of provided scope nodes (and optionally scopes nested within them) but will fall back on traversing the entire AST from root if a null scope nodes list is provided. Also allows for a callback to notify when starting on one of the provided scope nodes.

Parameters:

root - If scopeNodes is null, this method will just traverse 'root' instead. If scopeNodes is not null, this parameter is ignored.

traverseFunctionOutOfBand

public void traverseFunctionOutOfBand(Node node,
                                      AbstractScope<?,?> 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 java.lang.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.ChangeScopeRootCallback 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).

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.

getAbstractScope

public AbstractScope<?,?> getAbstractScope()

Gets the current scope.

isHoistScope

public boolean isHoistScope()

getClosestHoistScopeRoot

public Node getClosestHoistScopeRoot()

getClosestContainerScope

public AbstractScope<?,?> getClosestContainerScope()

getClosestHoistScope

public AbstractScope<?,?> getClosestHoistScope()

getScope

public Scope getScope()

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.

getScopeCreator

public com.google.javascript.jscomp.ScopeCreator getScopeCreator()

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,
                   java.lang.String... arguments)

Reports a diagnostic (error or warning)

reportCodeChange

public void reportCodeChange()

reportCodeChange

public void reportCodeChange(Node n)