8308753: Class-File API transition to Preview

Reviewed-by: ihse, mchung, vromero

src/java.base/share/classes/java/lang/classfile/MethodBuilder.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2022, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package java.lang.classfile;
+
+import java.util.Optional;
+import java.util.function.Consumer;
+
+import java.lang.classfile.constantpool.Utf8Entry;
+import jdk.internal.classfile.impl.ChainedMethodBuilder;
+import jdk.internal.classfile.impl.TerminalMethodBuilder;
+import java.lang.reflect.AccessFlag;
+import jdk.internal.javac.PreviewFeature;
+
+/**
+ * A builder for methods.  Builders are not created directly; they are passed
+ * to handlers by methods such as {@link ClassBuilder#withMethod(Utf8Entry, Utf8Entry, int, Consumer)}
+ * or to method transforms.  The elements of a method can be specified
+ * abstractly (by passing a {@link MethodElement} to {@link #with(ClassFileElement)}
+ * or concretely by calling the various {@code withXxx} methods.
+ *
+ * @see MethodTransform
+ *
+ * @since 22
+ */
+@PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
+public sealed interface MethodBuilder
+        extends ClassFileBuilder<MethodElement, MethodBuilder>
+        permits ChainedMethodBuilder, TerminalMethodBuilder {
+
+    /**
+     * {@return the {@link MethodModel} representing the method being transformed,
+     * if this method builder represents the transformation of some {@link MethodModel}}
+     */
+    Optional<MethodModel> original();
+
+    /**
+     * Sets the method access flags.
+     * @param flags the access flags, as a bit mask
+     * @return this builder
+     */
+    default MethodBuilder withFlags(int flags) {
+        return with(AccessFlags.ofMethod(flags));
+    }
+
+    /**
+     * Sets the method access flags.
+     * @param flags the access flags, as a bit mask
+     * @return this builder
+     */
+    default MethodBuilder withFlags(AccessFlag... flags) {
+        return with(AccessFlags.ofMethod(flags));
+    }
+
+    /**
+     * Build the method body for this method.
+     * @param code a handler receiving a {@link CodeBuilder}
+     * @return this builder
+     */
+    MethodBuilder withCode(Consumer<? super CodeBuilder> code);
+
+    /**
+     * Build the method body for this method by transforming the body of another
+     * method.
+     *
+     * @implNote
+     * <p>This method behaves as if:
+     * {@snippet lang=java :
+     *     withCode(b -> b.transformCode(code, transform));
+     * }
+     *
+     * @param code the method body to be transformed
+     * @param transform the transform to apply to the method body
+     * @return this builder
+     */
+    MethodBuilder transformCode(CodeModel code, CodeTransform transform);
+}