Add NodeUtil.isShallowStatementTree method

This replaces existing calls to "n == null || NodeUtil.isStatementBlock(n) || NodeUtil.isControlStructure(n)". It's more useful in the child CL which adds SWITCH_BODY to this method, so that we don't have to individually refactor all the callers.

PiperOrigin-RevId: 715001274

src/com/google/javascript/jscomp/DeclaredGlobalExternsOnWindow.java

@@ -24,11 +24,12 @@
 import java.util.Set;
 
 /**
- * A compiler pass to normalize externs by declaring global names on
- * the "window" object, if it is declared in externs.
- * The new declarations are added to the window instance, not to Window.prototype.
+ * A compiler pass to normalize externs by declaring global names on the "window" object, if it is
+ * declared in externs. The new declarations are added to the window instance, not to
+ * Window.prototype.
  */
-class DeclaredGlobalExternsOnWindow implements CompilerPass, NodeTraversal.Callback {
+class DeclaredGlobalExternsOnWindow extends NodeTraversal.AbstractShallowStatementCallback
+    implements CompilerPass {
 
   private static final String WINDOW_NAME = "window";
 
@@ -111,13 +112,6 @@ private static void addExtern(Node node, boolean defineOnWindow) {
     node.getGrandparent().addChildToBack(IR.exprResult(newNode));
   }
 
-  @Override
-  public boolean shouldTraverse(NodeTraversal nodeTraversal, Node n, Node parent) {
-    return parent == null
-        || NodeUtil.isControlStructure(parent)
-        || NodeUtil.isStatementBlock(parent);
-  }
-
   @Override
   public void visit(NodeTraversal t, Node n, Node parent) {
     if (n.isFunction()) {

src/com/google/javascript/jscomp/FindModuleDependencies.java

@@ -79,9 +79,7 @@ public boolean shouldTraverse(NodeTraversal nodeTraversal, Node n, Node parent)
         return false;
       }
       // Shallow traversal, since we don't need to inspect within functions or expressions.
-      if (parent == null
-          || NodeUtil.isControlStructure(parent)
-          || NodeUtil.isStatementBlock(parent)) {
+      if (NodeUtil.isShallowStatementTree(parent)) {
         if (n.isExprResult()) {
           Node maybeGetProp = n.getFirstFirstChild();
           if (maybeGetProp != null
@@ -144,9 +142,7 @@ public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
   @Override
   public void visit(NodeTraversal t, Node n, Node parent) {
     ModuleLoader.ResolutionMode resolutionMode = compiler.getOptions().moduleResolutionMode;
-    if (parent == null
-        || NodeUtil.isControlStructure(parent)
-        || NodeUtil.isStatementBlock(parent)) {
+    if (NodeUtil.isShallowStatementTree(parent)) {
       if (n.isExprResult()) {
         Node maybeGetProp = n.getFirstFirstChild();
         if (maybeGetProp != null

src/com/google/javascript/jscomp/NodeTraversal.java

@@ -264,9 +264,7 @@ public final boolean shouldTraverse(NodeTraversal nodeTraversal, Node n, Node pa
   public abstract static class AbstractShallowStatementCallback implements Callback {
     @Override
     public final boolean shouldTraverse(NodeTraversal nodeTraversal, Node n, Node parent) {
-      return parent == null
-          || NodeUtil.isControlStructure(parent)
-          || NodeUtil.isStatementBlock(parent);
+      return NodeUtil.isShallowStatementTree(parent);
     }
   }
 

src/com/google/javascript/jscomp/NodeUtil.java

@@ -4526,15 +4526,22 @@ public boolean apply(Node n) {
   static final Predicate<Node> MATCH_ANYTHING_BUT_NON_ARROW_FUNCTION =
       n -> !NodeUtil.isNonArrowFunction(n);
 
+  /**
+   * Whether the given node's subtree may contain statements, excepting nested functions
+   *
+   * <p>This is useful for traversing all statements in a given script or function without
+   * traversing into nested functions, so it will return true for e.g. a BLOCK or SWITCH statement.
+   */
+  public static boolean isShallowStatementTree(Node n) {
+    return n == null || NodeUtil.isControlStructure(n) || NodeUtil.isStatementBlock(n);
+  }
+
   /** A predicate for matching statements without exiting the current scope. */
   static class MatchShallowStatement implements Predicate<Node> {
     @Override
     public boolean apply(Node n) {
       Node parent = n.getParent();
-      return n.isRoot()
-          || n.isBlock()
-          || (!n.isFunction()
-              && (parent == null || isControlStructure(parent) || isStatementBlock(parent)));
+      return n.isRoot() || n.isBlock() || (!n.isFunction() && isShallowStatementTree(parent));
     }
   }
 

src/com/google/javascript/jscomp/ProcessCommonJSModules.java

@@ -601,9 +601,7 @@ public boolean shouldTraverse(NodeTraversal nodeTraversal, Node n, Node parent)
     @Override
     public void visit(NodeTraversal t, Node n, Node parent) {
       // Check for goog.provide or goog.module statements
-      if (parent == null
-          || NodeUtil.isControlStructure(parent)
-          || NodeUtil.isStatementBlock(parent)) {
+      if (NodeUtil.isShallowStatementTree(parent)) {
         if (n.isExprResult()) {
           Node maybeGetProp = n.getFirstFirstChild();
           if (maybeGetProp != null

src/com/google/javascript/jscomp/SyntacticScopeCreator.java

@@ -309,7 +309,7 @@ private void scanVars(Node n, @Nullable Scope hoistScope, @Nullable Scope blockS
 
       // Variables can only occur in statement-level nodes, so
       // we only need to traverse children in a couple special cases.
-      if (NodeUtil.isControlStructure(n) || NodeUtil.isStatementBlock(n)) {
+      if (NodeUtil.isShallowStatementTree(n)) {
         for (Node child = n.getFirstChild(); child != null;) {
           Node next = child.getNext();
           scanVars(child, hoistScope, enteringNewBlock ? null : blockScope);

src/com/google/javascript/jscomp/lint/CheckJSDocStyle.java

@@ -438,9 +438,7 @@ public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
       }
 
       // Shallow traversal, since we don't need to inspect within functions or expressions.
-      if (parent == null
-          || NodeUtil.isControlStructure(parent)
-          || NodeUtil.isStatementBlock(parent)) {
+      if (NodeUtil.isShallowStatementTree(parent)) {
         if (n.isReturn() && n.hasChildren()) {
           found = true;
           return false;