/*

 * Copyright (c) 2017, 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.

 */

package jdk.experimental.bytecode;

/**

 * Base builder for attribute containing class file entities.

 *

 * @param <S> the type of the symbol representation

 * @param <T> the type of type descriptors representation

 * @param <E> the type of pool entries

 * @param <D> the type of this builder

 */

 public class AttributeBuilder<S, T, E, D extends AttributeBuilder<S, T, E, D>>

        extends AbstractBuilder<S, T, E, D> {

     /**

      * The number of attributes.

      */

    protected int nattrs;

    /**

     * The attributes represented as bytes.

     */

    protected GrowableByteBuffer attributes = new GrowableByteBuffer();

    /**

     * Create an attribute builder.

     *

     * @param poolHelper the helper to build the constant pool

     * @param typeHelper the helper to use to manipulate type descriptors

     */

    public AttributeBuilder(PoolHelper<S, T, E> poolHelper, TypeHelper<S, T> typeHelper) {

        super(poolHelper, typeHelper);

    }

    /**

     * Add a class file Attribute.  Defined as:

     * <pre>

     * {@code   attribute_info {

     *     u2 attribute_name_index;

     *     u4 attribute_length;

     *     u1 info[attribute_length];

     *   }}

     * </pre>

     *

     * @param name the attribute name

     * @param bytes the bytes of the attribute info

     * @return this builder, for chained calls

     */

    public D withAttribute(CharSequence name, byte[] bytes) {

        attributes.writeChar(poolHelper.putUtf8(name));

        attributes.writeInt(bytes.length);

        attributes.writeBytes(bytes);

        nattrs++;

        return thisBuilder();

    }

    /**

     * Add a class file Attribute, using a writer.  Defined as:

     * <pre>

     * {@code   attribute_info {

     *     u2 attribute_name_index;

     *     u4 attribute_length;

     *     u1 info[attribute_length];

     *   }}

     * </pre>

     *

     * @param <Z> the type of the object representing the attribute

     * @param name the attribute name

     * @param attr the representation of the attribute

     * @param attrWriter the writer which transform the attribute representation into bytes

     * @return this builder, for chained calls

     */

    public <Z> D withAttribute(CharSequence name, Z attr, AttributeWriter<S, T, E, Z> attrWriter) {

        attributes.writeChar(poolHelper.putUtf8(name));

        int offset = attributes.offset;

        attributes.writeInt(0);

        attrWriter.write(attr, poolHelper, attributes);

        int len = attributes.offset - offset - 4;

        attributes.withOffset(offset, buf -> buf.writeInt(len));

        nattrs++;

        return thisBuilder();

    }

     /**

      * Writer for transforming attribute representations to bytes

      *

      * @param <S> the type of symbol representation

      * @param <T> the type of type descriptors representation

      * @param <E> the type of pool entries

      * @param <A> the type of the object representing the attribute

      */

    public interface AttributeWriter<S, T, E, A> {

        /**

         * Write an attribute representation into a byte buffer.

         *

         * @param attr the representation of the attribute

         * @param poolHelper the constant pool helper

         * @param buf the buffer to collect the bytes

         */

        void write(A attr, PoolHelper<S, T, E> poolHelper, GrowableByteBuffer buf);

    }

}