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/* Copyright (c) 2005-2014 Rexx Language Association. All rights reserved.    */
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/*----------------------------------------------------------------------------*/
/******************************************************************************/
/* REXX Translator                                                            */
/*                                                                            */
/* Primitive Drop Parse Class                                                 */
/*                                                                            */
/******************************************************************************/
#include "RexxCore.h"
#include "QueueClass.hpp"
#include "RexxActivation.hpp"
#include "DropInstruction.hpp"
#include "ExpressionBaseVariable.hpp"
#include "Activity.hpp"
#include "BufferClass.hpp"


/**
 * Complete construction of a drop instruction.
 *
 * @param varCount The count of variables.
 * @param variable_list
 *                 The list of variables, a queue with the variables
 *                 stored in reverse order.
 */
RexxInstructionDrop::RexxInstructionDrop(size_t varCount, QueueClass *variable_list)
{
    // copy each of the variables from the queue into the object storage.
    // the copy is done back to front because the queue has them in LIFO order.
    variableCount = varCount;
    while (varCount > 0)
    {
        variables[--varCount] = (RexxVariableBase *)variable_list->pop();
    }
}


/**
 * Perform garbage collection on a live object.
 *
 * @param liveMark The current live mark.
 */
void RexxInstructionDrop::live(size_t liveMark)
{
    // must be first one marked
    memory_mark(nextInstruction);
    for (size_t i = 0; i < variableCount; i++)
    {
        memory_mark(variables[i]);
    }
}


/**
 * Perform generalized live marking on an object.  This is
 * used when mark-and-sweep processing is needed for purposes
 * other than garbage collection.
 *
 * @param reason The reason for the marking call.
 */
void RexxInstructionDrop::liveGeneral(MarkReason reason)
{
    // must be first one marked
    memory_mark_general(nextInstruction);
    for (size_t i = 0; i < variableCount; i++)
    {
        memory_mark_general(variables[i]);
    }
}


/**
 * Flatten a source object.
 *
 * @param envelope The envelope that will hold the flattened object.
 */
void RexxInstructionDrop::flatten(Envelope *envelope)
{
    setUpFlatten(RexxInstructionDrop)

    flattenRef(nextInstruction);

    for (size_t i = 0; i < variableCount; i++)
    {
        flattenRef(variables[i]);
    }

    cleanUpFlatten
}

/**
 * Execute a drop instruction.
 *
 * @param context The current execution context.
 * @param stack   The current evaluation stack.
 */
void RexxInstructionDrop::execute(RexxActivation *context, ExpressionStack *stack)
{
    // trace if necessary
    context->traceInstruction(this);

    // loop through the list telling each variable to drop.
    for (size_t i = 0; i < variableCount; i++)
    {
        variables[i]->drop(context);
    }

    // standard debug pause.
    context->pauseInstruction();
}