/*

 * Copyright (c) 2007, 2009, 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.IOException;

import java.util.Iterator;

import java.util.NoSuchElementException;

/**

 * See JVMS3, section 4.8.3.

 *

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

 *  deletion without notice.</b>

 */

public class Code_attribute extends Attribute {

    public class InvalidIndex extends AttributeException {

        private static final long serialVersionUID = -8904527774589382802L;

        InvalidIndex(int index) {

            this.index = index;

        }

        @Override

        public String getMessage() {

            // i18n

            return "invalid index " + index + " in Code attribute";

        }

        public final int index;

    }

    Code_attribute(ClassReader cr, int name_index, int length)

            throws IOException, ConstantPoolException {

        super(name_index, length);

        max_stack = cr.readUnsignedShort();

        max_locals = cr.readUnsignedShort();

        code_length = cr.readInt();

        code = new byte[code_length];

        cr.readFully(code);

        exception_table_langth = cr.readUnsignedShort();

        exception_table = new Exception_data[exception_table_langth];

        for (int i = 0; i < exception_table_langth; i++)

            exception_table[i] = new Exception_data(cr);

        attributes = new Attributes(cr);

    }

    public int getByte(int offset) throws InvalidIndex {

        if (offset < 0 || offset >= code.length)

            throw new InvalidIndex(offset);

        return code[offset];

    }

    public int getUnsignedByte(int offset) throws InvalidIndex {

        if (offset < 0 || offset >= code.length)

            throw new InvalidIndex(offset);

        return code[offset] & 0xff;

    }

    public int getShort(int offset) throws InvalidIndex {

        if (offset < 0 || offset + 1 >= code.length)

            throw new InvalidIndex(offset);

        return (code[offset] << 8) | (code[offset + 1] & 0xFF);

    }

    public int getUnsignedShort(int offset) throws InvalidIndex {

        if (offset < 0 || offset + 1 >= code.length)

            throw new InvalidIndex(offset);

        return ((code[offset] << 8) | (code[offset + 1] & 0xFF)) & 0xFFFF;

    }

    public int getInt(int offset) throws InvalidIndex {

        if (offset < 0 || offset + 3 >= code.length)

            throw new InvalidIndex(offset);

        return (getShort(offset) << 16) | (getShort(offset + 2) & 0xFFFF);

    }

    public <R, D> R accept(Visitor<R, D> visitor, D data) {

        return visitor.visitCode(this, data);

    }

    public Iterable<Instruction> getInstructions() {

        return new Iterable<Instruction>() {

            public Iterator<Instruction> iterator() {

                return new Iterator<Instruction>() {

                    public boolean hasNext() {

                        return (next != null);

                    }

                    public Instruction next() {

                        if (next == null)

                            throw new NoSuchElementException();

                        current = next;

                        pc += current.length();

                        next = (pc < code.length ? new Instruction(code, pc) : null);

                        return current;

                    }

                    public void remove() {

                        throw new UnsupportedOperationException("Not supported.");

                    }

                    Instruction current = null;

                    int pc = 0;

                    Instruction next = new Instruction(code, pc);

                };

            }

        };

    }

    public final int max_stack;

    public final int max_locals;

    public final int code_length;

    public final byte[] code;

    public final int exception_table_langth;

    public final Exception_data[] exception_table;

    public final Attributes attributes;

    public class Exception_data {

        Exception_data(ClassReader cr) throws IOException {

            start_pc = cr.readUnsignedShort();

            end_pc = cr.readUnsignedShort();

            handler_pc = cr.readUnsignedShort();

            catch_type = cr.readUnsignedShort();

        }

        public final int start_pc;

        public final int end_pc;

        public final int handler_pc;

        public final int catch_type;

    }

}