content: /*
   * 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 openjdk.tools.classfile;
  
  import java.io.IOException;
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  
  /**
   * 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 = (pc < code.length ? new Instruction(code, pc) : null);
  
          };
      }
  
      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;
      }
  }
  