Add initial support for Java 14 language features

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=303367644

.travis.yml

@@ -9,6 +9,7 @@ notifications:
 
 jdk:
   - openjdk11
+  - openjdk14
   - openjdk-ea
 
 matrix:

core/pom.xml

@@ -256,4 +256,32 @@
       </plugin>
     </plugins>
   </build>
+
+  <profiles>
+    <profile>
+      <id>jdk11</id>
+      <activation>
+        <jdk>(,14)</jdk>
+      </activation>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <configuration>
+              <excludes>
+                <exclude>**/Java14InputAstVisitor.java</exclude>
+              </excludes>
+            </configuration>
+          </plugin>
+          <plugin>
+            <artifactId>maven-javadoc-plugin</artifactId>
+            <configuration>
+              <excludePackageNames>com.google.googlejavaformat.java.java14</excludePackageNames>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+  </profiles>
 </project>

core/src/main/java/com/google/googlejavaformat/java/Formatter.java

@@ -14,6 +14,8 @@
 
 package com.google.googlejavaformat.java;
 
+import static com.google.common.base.StandardSystemProperty.JAVA_CLASS_VERSION;
+import static com.google.common.base.StandardSystemProperty.JAVA_SPECIFICATION_VERSION;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.collect.ImmutableList;
@@ -40,6 +42,7 @@
 import com.sun.tools.javac.util.Options;
 import java.io.IOError;
 import java.io.IOException;
+import java.lang.reflect.Method;
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -115,6 +118,7 @@ static void format(final JavaInput javaInput, JavaOutput javaOutput, JavaFormatt
     DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>();
     context.put(DiagnosticListener.class, diagnostics);
     Options.instance(context).put("allowStringFolding", "false");
+    Options.instance(context).put("--enable-preview", "true");
     JCCompilationUnit unit;
     JavacFileManager fileManager = new JavacFileManager(context, true, UTF_8);
     try {
@@ -149,7 +153,21 @@ public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOExcept
     }
     OpsBuilder builder = new OpsBuilder(javaInput, javaOutput);
     // Output the compilation unit.
-    new JavaInputAstVisitor(builder, options.indentationMultiplier()).scan(unit, null);
+    JavaInputAstVisitor visitor;
+    if (getMajor() >= 14) {
+      try {
+        visitor =
+            Class.forName("com.google.googlejavaformat.java.java14.Java14InputAstVisitor")
+                .asSubclass(JavaInputAstVisitor.class)
+                .getConstructor(OpsBuilder.class, int.class)
+                .newInstance(builder, options.indentationMultiplier());
+      } catch (ReflectiveOperationException e) {
+        throw new LinkageError(e.getMessage(), e);
+      }
+    } else {
+      visitor = new JavaInputAstVisitor(builder, options.indentationMultiplier());
+    }
+    visitor.scan(unit, null);
     builder.sync(javaInput.getText().length());
     builder.drain();
     Doc doc = new DocBuilder().withOps(builder.build()).build();
@@ -158,6 +176,23 @@ public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOExcept
     javaOutput.flush();
   }
 
+  // Runtime.Version was added in JDK 9, so use reflection to access it to preserve source
+  // compatibility with Java 8.
+  private static int getMajor() {
+    try {
+      Method versionMethod = Runtime.class.getMethod("version");
+      Object version = versionMethod.invoke(null);
+      return (int) version.getClass().getMethod("major").invoke(version);
+    } catch (Exception e) {
+      // continue below
+    }
+    int version = (int) Double.parseDouble(JAVA_CLASS_VERSION.value());
+    if (49 <= version && version <= 52) {
+      return version - (49 - 5);
+    }
+    throw new IllegalStateException("Unknown Java version: " + JAVA_SPECIFICATION_VERSION.value());
+  }
+
   static boolean errorDiagnostic(Diagnostic<?> input) {
     if (input.getKind() != Diagnostic.Kind.ERROR) {
       return false;

core/src/main/java/com/google/googlejavaformat/java/JavaInput.java

@@ -39,6 +39,7 @@
 import com.sun.tools.javac.util.Context;
 import com.sun.tools.javac.util.Log;
 import com.sun.tools.javac.util.Log.DeferredDiagnosticHandler;
+import com.sun.tools.javac.util.Options;
 import java.io.IOException;
 import java.net.URI;
 import java.util.ArrayList;
@@ -347,6 +348,7 @@ static ImmutableList<Tok> buildToks(String text, ImmutableSet<TokenKind> stopTok
       throws FormatterException {
     stopTokens = ImmutableSet.<TokenKind>builder().addAll(stopTokens).add(TokenKind.EOF).build();
     Context context = new Context();
+    Options.instance(context).put("--enable-preview", "true");
     new JavacFileManager(context, true, UTF_8);
     DiagnosticCollector<JavaFileObject> diagnosticCollector = new DiagnosticCollector<>();
     context.put(DiagnosticListener.class, diagnosticCollector);

core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java

@@ -134,6 +134,7 @@
 import com.sun.source.util.TreePathScanner;
 import com.sun.tools.javac.code.Flags;
 import com.sun.tools.javac.tree.JCTree;
+import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
 import com.sun.tools.javac.tree.TreeScanner;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
@@ -154,10 +155,10 @@
  * An AST visitor that builds a stream of {@link Op}s to format from the given {@link
  * CompilationUnitTree}.
  */
-public final class JavaInputAstVisitor extends TreePathScanner<Void, Void> {
+public class JavaInputAstVisitor extends TreePathScanner<Void, Void> {
 
   /** Direction for Annotations (usually VERTICAL). */
-  enum Direction {
+  protected enum Direction {
     VERTICAL,
     HORIZONTAL;
 
@@ -211,7 +212,7 @@ static AllowTrailingBlankLine valueOf(boolean b) {
   }
 
   /** Whether to include braces. */
-  enum BracesOrNot {
+  protected enum BracesOrNot {
     YES,
     NO;
 
@@ -259,7 +260,7 @@ boolean isYes() {
   }
 
   /** Whether these declarations are the first in the block. */
-  enum FirstDeclarationsOrNot {
+  protected enum FirstDeclarationsOrNot {
     YES,
     NO;
 
@@ -268,14 +269,14 @@ boolean isYes() {
     }
   }
 
-  private final OpsBuilder builder;
+  protected final OpsBuilder builder;
 
-  private static final Indent.Const ZERO = Indent.Const.ZERO;
-  private final int indentMultiplier;
-  private final Indent.Const minusTwo;
-  private final Indent.Const minusFour;
-  private final Indent.Const plusTwo;
-  private final Indent.Const plusFour;
+  protected static final Indent.Const ZERO = Indent.Const.ZERO;
+  protected final int indentMultiplier;
+  protected final Indent.Const minusTwo;
+  protected final Indent.Const minusFour;
+  protected final Indent.Const plusTwo;
+  protected final Indent.Const plusFour;
 
   private static final ImmutableList<Op> breakList(Optional<BreakTag> breakTag) {
     return ImmutableList.of(Doc.Break.make(Doc.FillMode.UNIFIED, " ", ZERO, breakTag));
@@ -382,7 +383,7 @@ public Void visitCompilationUnit(CompilationUnitTree node, Void unused) {
   }
 
   /** Skips over extra semi-colons at the top-level, or in a class member declaration lists. */
-  private void dropEmptyDeclarations() {
+  protected void dropEmptyDeclarations() {
     if (builder.peekToken().equals(Optional.of(";"))) {
       while (builder.peekToken().equals(Optional.of(";"))) {
         builder.forcedBreak();
@@ -1331,12 +1332,19 @@ public Void visitAnnotatedType(AnnotatedTypeTree node, Void unused) {
     return null;
   }
 
+  // TODO(cushon): Use Flags.COMPACT_RECORD_CONSTRUCTOR once if/when we drop support for Java 11
+  protected static final long COMPACT_RECORD_CONSTRUCTOR = 1L << 51;
+
   @Override
   public Void visitMethod(MethodTree node, Void unused) {
     sync(node);
     List<? extends AnnotationTree> annotations = node.getModifiers().getAnnotations();
     List<? extends AnnotationTree> returnTypeAnnotations = ImmutableList.of();
 
+    boolean isRecordConstructor =
+        (((JCMethodDecl) node).mods.flags & COMPACT_RECORD_CONSTRUCTOR)
+            == COMPACT_RECORD_CONSTRUCTOR;
+
     if (!node.getTypeParameters().isEmpty() && !annotations.isEmpty()) {
       int typeParameterStart = getStartPosition(node.getTypeParameters().get(0));
       for (int i = 0; i < annotations.size(); i++) {
@@ -1406,7 +1414,9 @@ public Void visitMethod(MethodTree node, Void unused) {
         name = builder.peekToken().get();
       }
       token(name);
-      token("(");
+      if (!isRecordConstructor) {
+        token("(");
+      }
       // end of name and type scope
       builder.close();
     }
@@ -1416,12 +1426,14 @@ public Void visitMethod(MethodTree node, Void unused) {
     builder.open(Indent.If.make(breakBeforeType, plusFour, ZERO));
     builder.open(ZERO);
     {
-      if (!node.getParameters().isEmpty() || node.getReceiverParameter() != null) {
-        // Break before args.
-        builder.breakToFill("");
-        visitFormals(Optional.ofNullable(node.getReceiverParameter()), node.getParameters());
+      if (!isRecordConstructor) {
+        if (!node.getParameters().isEmpty() || node.getReceiverParameter() != null) {
+          // Break before args.
+          builder.breakToFill("");
+          visitFormals(Optional.ofNullable(node.getReceiverParameter()), node.getParameters());
+        }
+        token(")");
       }
-      token(")");
       if (dims != null) {
         maybeAddDims(dims);
       }
@@ -1795,17 +1807,22 @@ public Void visitCase(CaseTree node, Void unused) {
   @Override
   public Void visitSwitch(SwitchTree node, Void unused) {
     sync(node);
+    visitSwitch(node.getExpression(), node.getCases());
+    return null;
+  }
+
+  protected void visitSwitch(ExpressionTree expression, List<? extends CaseTree> cases) {
     token("switch");
     builder.space();
     token("(");
-    scan(skipParen(node.getExpression()), null);
+    scan(skipParen(expression), null);
     token(")");
     builder.space();
     tokenBreakTrailingComment("{", plusTwo);
     builder.blankLineWanted(BlankLineWanted.NO);
     builder.open(plusTwo);
     boolean first = true;
-    for (CaseTree caseTree : node.getCases()) {
+    for (CaseTree caseTree : cases) {
       if (!first) {
         builder.blankLineWanted(BlankLineWanted.PRESERVE);
       }
@@ -1816,7 +1833,6 @@ public Void visitSwitch(SwitchTree node, Void unused) {
     builder.forcedBreak();
     builder.blankLineWanted(BlankLineWanted.NO);
     token("}", plusFour);
-    return null;
   }
 
   @Override
@@ -2126,7 +2142,7 @@ private void visitStatement(
     }
   }
 
-  private void visitStatements(List<? extends StatementTree> statements) {
+  protected void visitStatements(List<? extends StatementTree> statements) {
     boolean first = true;
     PeekingIterator<StatementTree> it = Iterators.peekingIterator(statements.iterator());
     dropEmptyDeclarations();
@@ -2164,15 +2180,15 @@ public Void visitModifiers(ModifiersTree node, Void unused) {
   }
 
   /** Output combined modifiers and annotations and returns the trailing break. */
-  private List<Op> visitModifiers(
+  protected List<Op> visitModifiers(
       ModifiersTree modifiersTree,
       Direction annotationsDirection,
       Optional<BreakTag> declarationAnnotationBreak) {
     return visitModifiers(
         modifiersTree.getAnnotations(), annotationsDirection, declarationAnnotationBreak);
   }
 
-  private List<Op> visitModifiers(
+  protected List<Op> visitModifiers(
       List<? extends AnnotationTree> annotationTrees,
       Direction annotationsDirection,
       Optional<BreakTag> declarationAnnotationBreak) {
@@ -2339,7 +2355,7 @@ private static void walkInfix(
     }
   }
 
-  private void visitFormals(
+  protected void visitFormals(
       Optional<VariableTree> receiver, List<? extends VariableTree> parameters) {
     if (!receiver.isPresent() && parameters.isEmpty()) {
       return;
@@ -2559,7 +2575,7 @@ private void visitToDeclare(
   }
 
   /** Does not omit the leading '<', which should be associated with the type name. */
-  private void typeParametersRest(
+  protected void typeParametersRest(
       List<? extends TypeParameterTree> typeParameters, Indent plusIndent) {
     builder.open(plusIndent);
     builder.breakOp();
@@ -3446,7 +3462,7 @@ private void declareMany(List<VariableTree> fragments, Direction annotationDirec
   }
 
   /** Add a list of declarations. */
-  void addBodyDeclarations(
+  protected void addBodyDeclarations(
       List<? extends Tree> bodyDeclarations, BracesOrNot braces, FirstDeclarationsOrNot first0) {
     if (bodyDeclarations.isEmpty()) {
       if (braces.isYes()) {
@@ -3592,7 +3608,7 @@ private Direction fieldAnnotationDirection(ModifiersTree modifiers) {
    *
    * @param token the {@link String} to wrap in a {@link Doc.Token}
    */
-  final void token(String token) {
+  protected final void token(String token) {
     builder.token(
         token,
         Doc.Token.RealOrImaginary.REAL,
@@ -3606,7 +3622,7 @@ final void token(String token) {
    * @param token the {@link String} to wrap in a {@link Doc.Token}
    * @param plusIndentCommentsBefore extra indent for comments before this token
    */
-  final void token(String token, Indent plusIndentCommentsBefore) {
+  protected final void token(String token, Indent plusIndentCommentsBefore) {
     builder.token(
         token,
         Doc.Token.RealOrImaginary.REAL,
@@ -3620,7 +3636,7 @@ final void tokenBreakTrailingComment(String token, Indent breakAndIndentTrailing
         token, Doc.Token.RealOrImaginary.REAL, ZERO, Optional.of(breakAndIndentTrailingComment));
   }
 
-  private void markForPartialFormat() {
+  protected void markForPartialFormat() {
     if (!inExpression()) {
       builder.markForPartialFormat();
     }
@@ -3632,7 +3648,7 @@ private void markForPartialFormat() {
    *
    * @param node the ASTNode holding the input position
    */
-  final void sync(Tree node) {
+  protected final void sync(Tree node) {
     builder.sync(((JCTree) node).getStartPosition());
   }
 

core/src/main/java/com/google/googlejavaformat/java/RemoveUnusedImports.java

@@ -200,6 +200,7 @@ private static JCCompilationUnit parse(Context context, String javaInput)
       throws FormatterException {
     DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>();
     context.put(DiagnosticListener.class, diagnostics);
+    Options.instance(context).put("--enable-preview", "true");
     Options.instance(context).put("allowStringFolding", "false");
     JCCompilationUnit unit;
     JavacFileManager fileManager = new JavacFileManager(context, true, UTF_8);

core/src/main/java/com/google/googlejavaformat/java/StringWrapper.java

@@ -372,6 +372,7 @@ private static JCTree.JCCompilationUnit parse(String source, boolean allowString
     DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>();
     Context context = new Context();
     context.put(DiagnosticListener.class, diagnostics);
+    Options.instance(context).put("--enable-preview", "true");
     Options.instance(context).put("allowStringFolding", Boolean.toString(allowStringFolding));
     JCTree.JCCompilationUnit unit;
     JavacFileManager fileManager = new JavacFileManager(context, true, UTF_8);