8335642: Hide Transform implementation for Class-File API

Reviewed-by: asotona

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

@@ -27,8 +27,9 @@
 import java.lang.constant.ClassDesc;
 import java.util.function.Consumer;
 
-import java.lang.classfile.constantpool.ConstantPool;
 import java.lang.classfile.constantpool.ConstantPoolBuilder;
+
+import jdk.internal.classfile.impl.TransformImpl;
 import jdk.internal.javac.PreviewFeature;
 
 /**
@@ -71,25 +72,19 @@ default void accept(E e) {
      */
     ConstantPoolBuilder constantPool();
 
-    /**
-     * {@return whether the provided constant pool is compatible with this builder}
-     * @param source the constant pool to test compatibility with
-     */
-    default boolean canWriteDirect(ConstantPool source) {
-        return constantPool().canWriteDirect(source);
-    }
-
     /**
      * Apply a transform to a model, directing results to this builder.
      * @param model the model to transform
      * @param transform the transform to apply
+     * @return this builder
      */
-    default void transform(CompoundElement<E> model, ClassFileTransform<?, E, B> transform) {
+    default B transform(CompoundElement<E> model, ClassFileTransform<?, E, B> transform) {
         @SuppressWarnings("unchecked")
         B builder = (B) this;
-        var resolved = transform.resolve(builder);
+        var resolved = TransformImpl.resolve(transform, builder);
         resolved.startHandler().run();
         model.forEach(resolved.consumer());
         resolved.endHandler().run();
+        return builder;
     }
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, 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
@@ -24,7 +24,6 @@
  */
 package java.lang.classfile;
 
-import java.util.function.Consumer;
 import java.util.function.Supplier;
 
 import java.lang.classfile.attribute.RuntimeVisibleAnnotationsAttribute;
@@ -124,46 +123,4 @@ default void atStart(B builder) {
      * @return the chained transform
      */
     C andThen(C next);
-
-    /**
-     * The result of binding a transform to a builder.  Used primarily within
-     * the implementation to perform transformation.
-     *
-     * @param <E> the element type
-     *
-     * @since 22
-     */
-    @PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
-    interface ResolvedTransform<E extends ClassFileElement> {
-        /**
-         * {@return a {@link Consumer} to receive elements}
-         */
-        Consumer<E> consumer();
-
-        /**
-         * {@return an action to call at the end of transformation}
-         */
-        Runnable endHandler();
-
-        /**
-         * {@return an action to call at the start of transformation}
-         */
-        Runnable startHandler();
-    }
-
-    /**
-     * Bind a transform to a builder.  If the transform is chained, intermediate
-     * builders are created for each chain link.  If the transform is stateful
-     * (see, e.g., {@link ClassTransform#ofStateful(Supplier)}), the supplier is
-     * invoked to get a fresh transform object.
-     *
-     * <p>This method is a low-level method that should rarely be used by
-     * user code; most of the time, user code should prefer
-     * {@link ClassFileBuilder#transform(CompoundElement, ClassFileTransform)},
-     * which resolves the transform and executes it on the current builder.
-     *
-     * @param builder the builder to bind to
-     * @return the bound result
-     */
-    ResolvedTransform<E> resolve(B builder);
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, 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
@@ -171,15 +171,4 @@ static ClassTransform transformingFields(FieldTransform xform) {
     default ClassTransform andThen(ClassTransform t) {
         return new TransformImpl.ChainedClassTransform(this, t);
     }
-
-    /**
-     * @implSpec The default implementation returns a resolved transform bound
-     *           to the given class builder.
-     */
-    @Override
-    default ResolvedTransform<ClassElement> resolve(ClassBuilder builder) {
-        return new TransformImpl.ResolvedTransformImpl<>(e -> accept(builder, e),
-                                                         () -> atEnd(builder),
-                                                         () -> atStart(builder));
-    }
 }

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

@@ -87,6 +87,7 @@
 import static java.util.Objects.requireNonNull;
 import static jdk.internal.classfile.impl.BytecodeHelpers.handleDescToHandleInfo;
 
+import jdk.internal.classfile.impl.TransformImpl;
 import jdk.internal.javac.PreviewFeature;
 
 /**
@@ -190,7 +191,7 @@ public sealed interface CodeBuilder
      * @return this builder
      */
     default CodeBuilder transforming(CodeTransform transform, Consumer<CodeBuilder> handler) {
-        var resolved = transform.resolve(this);
+        var resolved = TransformImpl.resolve(transform, this);
         resolved.startHandler().run();
         handler.accept(new ChainedCodeBuilder(this, resolved.consumer()));
         resolved.endHandler().run();

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, 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
@@ -96,15 +96,4 @@ public void atEnd(CodeBuilder builder) {
     default CodeTransform andThen(CodeTransform t) {
         return new TransformImpl.ChainedCodeTransform(this, t);
     }
-
-    /**
-     * @implSpec The default implementation returns a resolved transform bound
-     *           to the given code builder.
-     */
-    @Override
-    default ResolvedTransform<CodeElement> resolve(CodeBuilder builder) {
-        return new TransformImpl.ResolvedTransformImpl<>(e -> accept(builder, e),
-                                                         () -> atEnd(builder),
-                                                         () -> atStart(builder));
-    }
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, 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
@@ -111,15 +111,4 @@ static FieldTransform dropping(Predicate<FieldElement> filter) {
     default FieldTransform andThen(FieldTransform t) {
         return new TransformImpl.ChainedFieldTransform(this, t);
     }
-
-    /**
-     * @implSpec The default implementation returns a resolved transform bound
-     *           to the given field builder.
-     */
-    @Override
-    default ResolvedTransform<FieldElement> resolve(FieldBuilder builder) {
-        return new TransformImpl.ResolvedTransformImpl<>(e -> accept(builder, e),
-                                                         () -> atEnd(builder),
-                                                         () -> atStart(builder));
-    }
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, 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
@@ -111,17 +111,6 @@ static MethodTransform transformingCode(CodeTransform xform) {
         return new TransformImpl.MethodCodeTransform(xform);
     }
 
-    /**
-     * @implSpec The default implementation returns a resolved transform bound
-     *           to the given method builder.
-     */
-    @Override
-    default ResolvedTransform<MethodElement> resolve(MethodBuilder builder) {
-        return new TransformImpl.ResolvedTransformImpl<>(e -> accept(builder, e),
-                                                         () -> atEnd(builder),
-                                                         () -> atStart(builder));
-    }
-
     /**
      * @implSpec
      * The default implementation returns this method transform chained with another

src/java.base/share/classes/jdk/internal/classfile/impl/AbstractDirectBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, 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
@@ -24,6 +24,7 @@
  */
 package jdk.internal.classfile.impl;
 
+import java.lang.classfile.constantpool.ConstantPool;
 import java.util.Optional;
 
 import java.lang.classfile.Attribute;
@@ -43,6 +44,10 @@ public SplitConstantPool constantPool() {
         return constantPool;
     }
 
+    public boolean canWriteDirect(ConstantPool source) {
+        return constantPool().canWriteDirect(source);
+    }
+
     public Optional<M> original() {
         return Optional.ofNullable(original);
     }