// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 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.ArrayList;
import java.util.List;
import org.objectweb.asm.tree.JumpInsnNode;
import org.objectweb.asm.tree.LabelNode;

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

  
The start of this subroutine. /** The start of this subroutine. */
  final LabelNode start;

  
The local variables that are read or written by this subroutine. The i-th element is true if
and only if the local variable at index i is read or written by this subroutine.
/**
   * The local variables that are read or written by this subroutine. The i-th element is true if
   * and only if the local variable at index i is read or written by this subroutine.
   */
  final boolean[] localsUsed;

  
The JSR instructions that jump to this subroutine. /** The JSR instructions that jump to this subroutine. */
  final List<JumpInsnNode> callers;

  
Constructs a new Subroutine. 
Params:
start – the start of this subroutine.
maxLocals – the local variables that are read or written by this subroutine.
caller – a JSR instruction that jump to this subroutine./**
   * Constructs a new {@link Subroutine}.
   *
   * @param start the start of this subroutine.
   * @param maxLocals the local variables that are read or written by this subroutine.
   * @param caller a JSR instruction that jump to this subroutine.
   */
  Subroutine(final LabelNode start, final int maxLocals, final JumpInsnNode caller) {
    this.start = start;
    this.localsUsed = new boolean[maxLocals];
    this.callers = new ArrayList<>();
    callers.add(caller);
  }

  
Constructs a copy of the given Subroutine. 
Params:
subroutine – the subroutine to copy./**
   * Constructs a copy of the given {@link Subroutine}.
   *
   * @param subroutine the subroutine to copy.
   */
  Subroutine(final Subroutine subroutine) {
    this.start = subroutine.start;
    this.localsUsed = new boolean[subroutine.localsUsed.length];
    this.callers = new ArrayList<>(subroutine.callers);
    System.arraycopy(subroutine.localsUsed, 0, this.localsUsed, 0, subroutine.localsUsed.length);
  }

  
Merges the given subroutine into this subroutine. The local variables read or written by the
given subroutine are marked as read or written by this one, and the callers of the given
subroutine are added as callers of this one (if both have the same start).
Params:
subroutine – another subroutine. This subroutine is left unchanged by this method.
Returns:
whether this subroutine has been modified by this method./**
   * Merges the given subroutine into this subroutine. The local variables read or written by the
   * given subroutine are marked as read or written by this one, and the callers of the given
   * subroutine are added as callers of this one (if both have the same start).
   *
   * @param subroutine another subroutine. This subroutine is left unchanged by this method.
   * @return whether this subroutine has been modified by this method.
   */
  public boolean merge(final Subroutine subroutine) {
    boolean changed = false;
    for (int i = 0; i < localsUsed.length; ++i) {
      if (subroutine.localsUsed[i] && !localsUsed[i]) {
        localsUsed[i] = true;
        changed = true;
      }
    }
    if (subroutine.start == start) {
      for (int i = 0; i < subroutine.callers.size(); ++i) {
        JumpInsnNode caller = subroutine.callers.get(i);
        if (!callers.contains(caller)) {
          callers.add(caller);
          changed = true;
        }
      }
    }
    return changed;
  }
}