Package com.google.javascript.jscomp

Class 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.

    • 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.

      • 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.

      • 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.

      • inModuleScope

        public boolean inModuleScope()
        Determines whether the traversal is currently in the global scope. Note that this returns false in a global block scope.

      • inGlobalOrModuleScope

        public boolean inGlobalOrModuleScope()

      • 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.

      • 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)