dataflowinterpreter.java

jboss规则引擎

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 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.drools.asm.tree.analysis;

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

import org.drools.asm.Opcodes;
import org.drools.asm.Type;
import org.drools.asm.tree.AbstractInsnNode;
import org.drools.asm.tree.FieldInsnNode;
import org.drools.asm.tree.LdcInsnNode;
import org.drools.asm.tree.MethodInsnNode;

/**
 * An {@link Interpreter} for {@link DataflowValue} values.
 * 
 * @author Eric Bruneton
 */
public class DataflowInterpreter
    implements
    Opcodes,
    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 :
                final 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() == Opcodes.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) {
        final DataflowValue dv = (DataflowValue) v;
        final DataflowValue dw = (DataflowValue) w;
        if ( dv.insns instanceof SmallSet && dw.insns instanceof SmallSet ) {
            final Set s = ((SmallSet) dv.insns).union( (SmallSet) dw.insns );
            if ( s == dv.insns && dv.size == dw.size ) {
                return v;
            } else {
                return new DataflowValue( Math.min( dv.size,
                                                    dw.size ),
                                          s );
            }
        }
        if ( dv.size != dw.size || !dv.insns.containsAll( dw.insns ) ) {
            final Set s = new HashSet();
            s.addAll( dv.insns );
            s.addAll( dw.insns );
            return new DataflowValue( Math.min( dv.size,
                                                dw.size ),
                                      s );
        }
        return v;
    }
}