package soot.coffi;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 1997 Clark Verbrugge
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 2.1 of the
 * License, or (at your option) any later version.
 * 
 * This program 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 Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-2.1.html>.
 * #L%
 */

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Instruction subclasses are used to represent parsed bytecode; each bytecode operation has a corresponding subclass of
 * Instruction.
 * <p>
 * Each subclass is derived from one of
 * <ul>
 * <li>Instruction</li>
 * <li>Instruction_noargs (an Instruction with no embedded arguments)</li>
 * <li>Instruction_byte (an Instruction with a single byte data argument)</li>
 * <li>Instruction_bytevar (a byte argument specifying a local variable)</li>
 * <li>Instruction_byteindex (a byte argument specifying a constant pool index)</li>
 * <li>Instruction_int (an Instruction with a single short data argument)</li>
 * <li>Instruction_intvar (a short argument specifying a local variable)</li>
 * <li>Instruction_intindex (a short argument specifying a constant pool index)</li>
 * <li>Instruction_intbranch (a short argument specifying a code offset)</li>
 * <li>Instruction_longbranch (an int argument specifying a code offset)</li>
 * </ul>
 *
 * @author Clark Verbrugge
 * @see Instruction
 * @see Instruction_noargs
 * @see Instruction_byte
 * @see Instruction_bytevar
 * @see Instruction_byteindex
 * @see Instruction_int
 * @see Instruction_intvar
 * @see Instruction_intindex
 * @see Instruction_intbranch
 * @see Instruction_longbranch
 * @see Instruction_Unknown
 */
abstract class Instruction_branch extends Instruction {
  private static final Logger logger = LoggerFactory.getLogger(Instruction_branch.class);
  public int arg_i;
  public Instruction target; // pointer to target instruction

  public Instruction_branch(byte c) {
    super(c);
    branches = true;
  }

  public String toString(cp_info constant_pool[]) {
    return super.toString(constant_pool) + argsep + "[label_" + Integer.toString(target.label) + "]";
  }

  public void offsetToPointer(ByteCode bc) {
    target = bc.locateInst(arg_i + label);
    if (target == null) {
      logger.warn("can't locate target of instruction");
      logger.debug(" which should be at byte address " + (label + arg_i));
    } else {
      target.labelled = true;
    }
  }

  // returns the array of instructions which might be the target of a
  // branch with this instruction, assuming the next instruction is next
  public Instruction[] branchpoints(Instruction next) {
    Instruction i[] = new Instruction[2];
    i[0] = target;
    i[1] = next;
    return i;
  }

  public String toString() {
    return super.toString() + "\t" + target.label;
  }
}
