PDG/PDG_PartitionByParity.C

/*
 * Copyright (c) 2025
 *      Side Effects Software Inc.  All rights reserved.
 *
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 *----------------------------------------------------------------------------
 * The Parition by Parity PDG node, which groups work items based on whether
 * or not a particular attribute value is even or odd.
 */

#include "PDG_PartitionByParity.h"

#include <PDG/PDG_AttributeRef.h>
#include <PDG/PDG_AttributeTypes.h>
#include <PDG/PDG_PartitionHolder.h>
#include <PDG/PDG_TypeRegistry.h>
#include <PDG/PDG_WorkItem.h>

#include <UT/UT_DSOVersion.h>

void registerPDGTypes(PDG_TypeRegistry* registry)
{
    PDG_NodeInterface partitioner("partitionbyparity");

    partitioner.addParameter(
        PDGT_Value::eString, "attributename", "Attribute Name");
    registry->registerPartitioner<HDK_Sample::PDG_PartitionByParity>(
        "partitionbyparity", "Partition by Parity", "Partitioners", partitioner);
}

using namespace HDK_Sample;

PDG_CallbackResult
PDG_PartitionByParity::onPartition(
                            PDG_PartitionHolder* holder,
                            const PDG_WorkItemArray& work_items,
                            const PDG_WorkItem* target)
{
    UT_StringHolder attrib_name = evaluateS("attributename");

    UT_WorkBuffer errors;
    for (auto&& work_item : work_items)
    {
        auto&& attrib = work_item->attributes().refRO(attrib_name);
        if (!attrib)
        {
            myNode->addWarningFmt(
                "'{}' has no attribute with the name '{}'",
                work_item->name(), attrib_name);
            continue;
        }

        fpreal value = 0;
        if (attrib.asNumber(value, 0) != PDG_AttributeCast::eSuccess)
        {
            myNode->addWarningFmt(
                "'{}' does not have a numeric value for attribute '{}'",
                work_item->name(), attrib_name);
            continue;
        }

        exint index = ((exint)value % 2 == 0) ? 0 : 1;
        if (!holder->addItemToPartition(work_item, index, false, errors))
        {
            myNode->addError(errors.buffer());
            return PDG_CallbackResult::eFailure;
        }
    }
    
    return PDG_CallbackResult::eSuccess;
}