TreeUtils { @CheckForNull public static Tree firstAncestor(Tree tree, Predicate<Tree> predicate) { Tree currentParent = tree.parent(); while (currentParent != null) { if (predicate.test(currentParent)) { return currentParent; } currentParent = currentParent.parent(); } return null; } private  TreeUtils(); @CheckForNull static Tree firstAncestor(Tree tree, Predicate<Tree> predicate); @CheckForNull static Tree firstAncestorOfKind(Tree tree, Kind... kinds); static List<Token> tokens(Tree tree); static List<Token> nonWhitespaceTokens(Tree tree); static boolean hasDescendant(Tree tree, Predicate<Tree> predicate); static Stream<Expression> flattenTuples(Expression expression); static Optional<Symbol> getSymbolFromTree(@Nullable Tree tree); @CheckForNull static ClassSymbol getClassSymbolFromDef(@Nullable ClassDef classDef); @CheckForNull static FunctionSymbol getFunctionSymbolFromDef(@Nullable FunctionDef functionDef); static List<Parameter> nonTupleParameters(FunctionDef functionDef); static List<Parameter> positionalParameters(FunctionDef functionDef); static List<FunctionDef> topLevelFunctionDefs(ClassDef classDef); @CheckForNull static RegularArgument argumentByKeyword(String keyword, List<Argument> arguments); @CheckForNull static RegularArgument nthArgumentOrKeyword(int argPosition, String keyword, List<Argument> arguments); static boolean isBooleanLiteral(Tree tree); static String nameFromExpression(Expression expression); @CheckForNull static LocationInFile locationInFile(Tree tree, @Nullable String fileId);  }
@Test public void first_ancestor() { String code = "" + "def outer():\n" + " def inner():\n" + " pass"; FileInput root = parse(code); FunctionDef outerFunction = (FunctionDef) root.statements().statements().get(0); FunctionDef innerFunction = (FunctionDef) outerFunction.body().statements().get(0); Statement passStatement = innerFunction.body().statements().get(0); assertThat(TreeUtils.firstAncestor(passStatement, TreeUtilsTest::isOuterFunction)).isEqualTo(outerFunction); }