8199196: Add javadoc support for preview features

Reviewed-by: ksrini

src/jdk.javadoc/share/classes/jdk/javadoc/internal/tool/ToolOption.java

@@ -196,6 +196,13 @@ public enum ToolOption {
         }
     },
 
+    ENABLE_PREVIEW("--enable-preview", STANDARD) {
+        @Override
+        public void process(Helper helper) throws InvalidValueException {
+            Option.PREVIEW.process(helper.getOptionHelper(), primaryName);
+        }
+    },
+
     // ----- doclet options -----
 
     DOCLET("-doclet", STANDARD, true), // handled in setDocletInvoker
@@ -404,7 +411,7 @@ public enum ToolOption {
 
     void process(Helper helper, String arg) throws OptionException, Option.InvalidValueException { }
 
-    void process(Helper helper) throws OptionException { }
+    void process(Helper helper) throws OptionException, Option.InvalidValueException { }
 
     List<String> getNames() {
         return names;

src/jdk.javadoc/share/classes/jdk/javadoc/internal/tool/resources/javadoc.properties

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -179,6 +179,10 @@ main.opt.source.arg=\
 main.opt.source.desc=\
     Provide source compatibility with specified release
 
+main.opt.enable.preview.desc=\
+    Enable preview language features. To be used in conjunction with\n\
+    either -source or --release.
+
 main.opt.extdirs.arg=\
     <dirlist>
 main.opt.extdirs.desc=\

test/langtools/jdk/javadoc/tool/EnablePreviewOption.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8199196
+ * @summary Test --enable-preview option in javadoc
+ * @modules jdk.javadoc/jdk.javadoc.internal.tool
+ * @library /tools/lib
+ * @build toolbox.ToolBox toolbox.TestRunner
+ * @run main EnablePreviewOption
+ */
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Predicate;
+
+import jdk.javadoc.internal.tool.Main;
+import jdk.javadoc.internal.tool.Main.Result;
+
+import static jdk.javadoc.internal.tool.Main.Result.*;
+
+import toolbox.TestRunner;
+import toolbox.ToolBox;
+
+public class EnablePreviewOption extends TestRunner {
+    public static void main(String... args) throws Exception {
+        new EnablePreviewOption().runTests();
+    }
+
+    ToolBox tb = new ToolBox();
+
+    Path file = Paths.get("C.java");
+    String thisVersion = System.getProperty("java.specification.version");
+    String prevVersion = String.valueOf(Integer.valueOf(thisVersion) - 1);
+
+    EnablePreviewOption() throws IOException {
+        super(System.err);
+        tb.writeFile(file, "public class C { }");
+    }
+
+    @Test
+    public void testSource() {
+        runTest(List.of("--enable-preview", "-source", thisVersion),
+                OK,
+                out -> !out.contains("error")
+                && out.contains("Building tree for all the packages and classes..."));
+    }
+
+    @Test
+    public void testRelease() {
+        runTest(List.of("--enable-preview", "--release", thisVersion),
+                OK,
+                out -> !out.contains("error")
+                && out.contains("Building tree for all the packages and classes..."));
+    }
+
+    @Test
+    public void testNoVersion() {
+        runTest(List.of("--enable-preview"),
+                CMDERR,
+                out -> out.contains("error: --enable-preview must be used with either -source or --release"));
+    }
+
+    @Test
+    public void testBadSource() {
+        runTest(List.of("--enable-preview", "-source", "BAD"),
+                ERROR,
+                out -> out.contains("error: invalid source release: BAD"));
+    }
+
+    @Test
+    public void testOldSource() {
+        runTest(List.of("--enable-preview", "-source", prevVersion),
+                CMDERR,
+                out -> out.matches("(?s)error: invalid source release .* with --enable-preview.*"));
+    }
+
+    private void runTest(List<String> options, Result expectedResult, Predicate<String> validate) {
+        System.err.println("running with options: " + options);
+        List<String> args = new ArrayList<>();
+        args.addAll(options);
+        args.add("-XDrawDiagnostics");
+        args.add(file.toString());
+        StringWriter out = new StringWriter();
+        PrintWriter pw = new PrintWriter(out);
+        int actualResult = Main.execute(args.toArray(new String[0]), pw);
+        System.err.println("actual result=" + actualResult);
+        System.err.println("actual output=" + out.toString());
+        if (actualResult != expectedResult.exitCode)
+            error("Exit code not as expected");
+        if (!validate.test(out.toString())) {
+            error("Output not as expected");
+        }
+    }
+}