/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000,2002,2003 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.objectweb.asm.tree.analysis;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.objectweb.asm.Constants;
import org.objectweb.asm.Type;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.FieldInsnNode;
import org.objectweb.asm.tree.LdcInsnNode;
import org.objectweb.asm.tree.MethodInsnNode;

/**
 * An {@link Interpreter} for {@link DataflowValue} values.
 * 
 * @author Eric Bruneton
 */

public class DataflowInterpreter implements Constants, Interpreter {

  public Value newValue (final Type type) {
    return new DataflowValue(type == null ? 1 : type.getSize());
  }

  public Value newOperation (final AbstractInsnNode insn) {
    int size;
    switch (insn.getOpcode()) {
      case LCONST_0:
      case LCONST_1:
      case DCONST_0:
      case DCONST_1:
        size = 2;
        break;
      case LDC:
        Object cst = ((LdcInsnNode)insn).cst;
        size = cst instanceof Long || cst instanceof Double ? 2 : 1;
        break;
      case GETSTATIC:
        size = Type.getType(((FieldInsnNode)insn).desc).getSize();
        break;
      default:
        size = 1;
    }
    return new DataflowValue(size, insn);
  }

  public Value copyOperation (final AbstractInsnNode insn, final Value value) {
    return new DataflowValue(value.getSize(), insn);
  }

  public Value unaryOperation (final AbstractInsnNode insn, final Value value) {
    int size;
    switch (insn.getOpcode()) {
      case LNEG:
      case DNEG:
      case I2L:
      case I2D:
      case L2D:
      case F2L:
      case F2D:
      case D2L:
        size = 2;
        break;
      case GETFIELD:
        size = Type.getType(((FieldInsnNode)insn).desc).getSize();
        break;
      default:
        size = 1;
    }
    return new DataflowValue(size, insn);
  }

  public Value binaryOperation (
    final AbstractInsnNode insn, 
    final Value value1, 
    final Value value2) 
  {
    int size;
    switch (insn.getOpcode()) {
      case LALOAD:
      case DALOAD:
      case LADD:
      case DADD:
      case LSUB:
      case DSUB:
      case LMUL:
      case DMUL:
      case LDIV:
      case DDIV:
      case LREM:
      case DREM:
      case LSHL:
      case LSHR:
      case LUSHR:
      case LAND:
      case LOR:
      case LXOR:
        size = 2;
        break;
      default:
        size = 1;
    }
    return new DataflowValue(size, insn);
  }

  public Value ternaryOperation (
    final AbstractInsnNode insn, 
    final Value value1, 
    final Value value2,
    final Value value3) 
  {
    return new DataflowValue(1, insn);
  }
  
  public Value naryOperation (final AbstractInsnNode insn, final List values) {
    int size;
    if (insn.getOpcode() == MULTIANEWARRAY) {
      size = 1;
    } else {
      size = Type.getReturnType(((MethodInsnNode)insn).desc).getSize();
    }
    return new DataflowValue(size, insn);
  }

  public Value merge (final Value v, final Value w) {
    DataflowValue dv = (DataflowValue)v;
    DataflowValue dw = (DataflowValue)w;
    if (dv.size != dw.size || !dv.insns.equals(dw.insns)) {
      Set s = new HashSet();
      s.addAll(dv.insns);
      s.addAll(dw.insns);
      return new DataflowValue(Math.min(dv.size, dw.size), s);
    }
    return v;
  }
}
