/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.bcel.verifier.structurals;


import java.util.ArrayList;

import org.apache.bcel.generic.InstructionHandle;

An InstructionContext offers convenient access
to information like control flow successors and
such.
/**
 * An InstructionContext offers convenient access
 * to information like control flow successors and
 * such.
 *
 */
public interface InstructionContext{

    
The getTag and setTag methods may be used for
temporary flagging, such as graph colouring.
Nothing in the InstructionContext object depends
on the value of the tag. JustIce does not use it.
See Also:
setTag(int tag)/**
     * The getTag and setTag methods may be used for
     * temporary flagging, such as graph colouring.
     * Nothing in the InstructionContext object depends
     * on the value of the tag. JustIce does not use it.
     *
     * @see #setTag(int tag)
     */
    int getTag();

    
The getTag and setTag methods may be used for
temporary flagging, such as graph colouring.
Nothing in the InstructionContext object depends
on the value of the tag. JustIce does not use it.
See Also:
getTag()/**
     * The getTag and setTag methods may be used for
     * temporary flagging, such as graph colouring.
     * Nothing in the InstructionContext object depends
     * on the value of the tag. JustIce does not use it.
     *
     * @see #getTag()
     */
    void setTag(int tag);

    
This method symbolically executes the Instruction
held in the InstructionContext.
It "merges in" the incoming execution frame situation
(see The Java Virtual Machine Specification, 2nd
edition, page 146).
By so doing, the outgoing execution frame situation
is calculated.
This method is JustIce-specific and is usually of
no sense for users of the ControlFlowGraph class.
They should use getInstruction().accept(Visitor),
possibly in conjunction with the ExecutionVisitor.
See Also:
ControlFlowGraph
ExecutionVisitor
getOutFrame(ArrayList<InstructionContext>)
Returns:
true -  if and only if the "outgoing" frame situation
changed from the one before execute()ing./**
     * This method symbolically executes the Instruction
     * held in the InstructionContext.
     * It "merges in" the incoming execution frame situation
     * (see The Java Virtual Machine Specification, 2nd
     * edition, page 146).
     * By so doing, the outgoing execution frame situation
     * is calculated.
     *
     * This method is JustIce-specific and is usually of
     * no sense for users of the ControlFlowGraph class.
     * They should use getInstruction().accept(Visitor),
     * possibly in conjunction with the ExecutionVisitor.
     *
     *
     * @see ControlFlowGraph
     * @see ExecutionVisitor
     * @see #getOutFrame(ArrayList)
     * @return true -  if and only if the "outgoing" frame situation
     * changed from the one before execute()ing.
     */
    boolean execute(Frame inFrame, ArrayList<InstructionContext> executionPredecessors,
            InstConstraintVisitor icv, ExecutionVisitor ev);

    Frame getInFrame();

    
This method returns the outgoing execution frame situation;
therefore it has to be calculated by execute(Frame, ArrayList)
first.
See Also:
execute(Frame, ArrayList, InstConstraintVisitor, ExecutionVisitor)/**
     * This method returns the outgoing execution frame situation;
     * therefore <B>it has to be calculated by execute(Frame, ArrayList)
     * first.</B>
     *
     * @see #execute(Frame, ArrayList, InstConstraintVisitor, ExecutionVisitor)
     */
    Frame getOutFrame(ArrayList<InstructionContext> executionPredecessors);

    
Returns the InstructionHandle this InstructionContext is wrapped around.
Returns:
The InstructionHandle this InstructionContext is wrapped around./**
     * Returns the InstructionHandle this InstructionContext is wrapped around.
     *
     * @return The InstructionHandle this InstructionContext is wrapped around.
     */
    InstructionHandle getInstruction();

    
Returns the usual control flow successors.
See Also:
getExceptionHandlers()/**
     * Returns the usual control flow successors.
     * @see #getExceptionHandlers()
     */
    InstructionContext[] getSuccessors();

    
Returns the exception handlers that protect this instruction.
They are special control flow successors.
/**
     * Returns the exception handlers that protect this instruction.
     * They are special control flow successors.
     */
    ExceptionHandler[] getExceptionHandlers();
}