subroutine.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.ArrayList;
import java.util.List;

import org.drools.asm.Label;
import org.drools.asm.tree.JumpInsnNode;

/**
 * A method subroutine (corresponds to a JSR instruction).
 * 
 * @author Eric Bruneton
 */
class Subroutine {

    Label     start;

    boolean[] access;

    List      callers;

    private Subroutine() {
    }

    public Subroutine(final Label start,
                      final int maxLocals,
                      final JumpInsnNode caller) {
        this.start = start;
        this.access = new boolean[maxLocals];
        this.callers = new ArrayList();
        this.callers.add( caller );
    }

    public Subroutine copy() {
        final Subroutine result = new Subroutine();
        result.start = this.start;
        result.access = new boolean[this.access.length];
        System.arraycopy( this.access,
                          0,
                          result.access,
                          0,
                          this.access.length );
        result.callers = new ArrayList( this.callers );
        return result;
    }

    public boolean merge(final Subroutine subroutine,
                         final boolean checkOverlap) throws AnalyzerException {
        if ( checkOverlap && subroutine.start != this.start ) {
            throw new AnalyzerException( "Overlapping sub routines" );
        }
        boolean changes = false;
        for ( int i = 0; i < this.access.length; ++i ) {
            if ( subroutine.access[i] && !this.access[i] ) {
                this.access[i] = true;
                changes = true;
            }
        }
        for ( int i = 0; i < subroutine.callers.size(); ++i ) {
            final Object caller = subroutine.callers.get( i );
            if ( !this.callers.contains( caller ) ) {
                this.callers.add( caller );
                changes = true;
            }
        }
        return changes;
    }
}