/*

 * Copyright (c) 2007, 2008, 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 com.sun.tools.classfile;

import java.io.BufferedInputStream;

import java.io.ByteArrayInputStream;

import java.io.DataInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.util.Objects;

/**

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public class ClassReader {

    ClassReader(ClassFile classFile, InputStream in, Attribute.Factory attributeFactory) throws IOException {

        this.classFile = Objects.requireNonNull(classFile);

        this.attributeFactory = Objects.requireNonNull(attributeFactory);

        this.in = new DataInputStream(new BufferedInputStream(in));

    }

    ClassFile getClassFile() {

        return classFile;

    }

    ConstantPool getConstantPool() {

        return classFile.constant_pool;

    }

    public Attribute readAttribute() throws IOException {

        int name_index = readUnsignedShort();

        int length = readInt();

        byte[] data = new byte[length];

        readFully(data);

        DataInputStream prev = in;

        in = new DataInputStream(new ByteArrayInputStream(data));

        try {

            return attributeFactory.createAttribute(this, name_index, data);

        } finally {

            in = prev;

        }

    }

    public void readFully(byte[] b) throws IOException {

        in.readFully(b);

    }

    public int readUnsignedByte() throws IOException {

        return in.readUnsignedByte();

    }

    public int readUnsignedShort() throws IOException {

        return in.readUnsignedShort();

    }

    public int readInt() throws IOException {

        return in.readInt();

    }

    public long readLong() throws IOException {

        return in.readLong();

    }

    public float readFloat() throws IOException {

        return in.readFloat();

    }

    public double readDouble() throws IOException {

        return in.readDouble();

    }

    public String readUTF() throws IOException {

        return in.readUTF();

    }

    private DataInputStream in;

    private ClassFile classFile;

    private Attribute.Factory attributeFactory;

}