/*
 * Copyright (c) 2007, 2013, 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 JVMS, section 4.8.3.
 
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.
/**
 * See JVMS, section 4.8.3.
 *
 *  <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 Code_attribute extends Attribute {
    public static 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_length = cr.readUnsignedShort();
        exception_table = new Exception_data[exception_table_length];
        for (int i = 0; i < exception_table_length; 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 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_length;
    public final Exception_data[] exception_table;
    public final Attributes attributes;

    public static 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;
    }
}