PDG_AttributeEvaluatorCache.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * COMMENTS:
 */

#ifndef __PDG_ATTRIBUTE_EVAL_CACHE_H__
#define __PDG_ATTRIBUTE_EVAL_CACHE_H__

#include "PDG_API.h"
#include "PDG_AttributeTypes.h"
#include "PDG_WorkItemTypes.h"

#include <UT/UT_Array.h>
#include <UT/UT_ArrayMap.h>
#include <UT/UT_WorkBuffer.h>

class PDG_AttributeEvaluator;
class PDG_WorkItem;

/**
 * Evaluates attributes from a list of work items using an attribute evaluator,
 * and caches the evaluation results. This is useful when e.g. sorting by 
 * attribute which may need to make multiple look-ups of the same attribute
 * value during the sorting process
 */
class PDG_API PDG_AttributeEvaluatorCache
{
public:
    /// Helper struct that contains the actual cached evaluation data
    struct CacheEntry
    {
        /// The cast result
        PDG_AttributeCast   myCast;

        /// The string value, if the attribute is castable to a string
        UT_WorkBuffer       myString;

        /// The float value, if the attribute is castable to a number
        fpreal              myFloat;

        /// Whether or not the entry has a float value
        bool                myHasFloat;
    };

public:
    /// Constructs a cache from an evaluator and a list of work items
                                PDG_AttributeEvaluatorCache(
                                    const PDG_AttributeEvaluator* evaluator,
                                    const PDG_WorkItemArray& work_items);

                                PDG_AttributeEvaluatorCache(
                                    const PDG_AttributeEvaluator* evaluator,
                                    const PDG_WorkItemConstArray& work_items);

    /// Returns the cache value for the specified work item
    inline const CacheEntry&    cacheEntry(const PDG_WorkItem* work_item) const
                                    {
                                        auto&& iter = myCacheMap.find(
                                            work_item);
                                        if (iter == myCacheMap.end())
                                            return theDefaultCacheEntry;

                                        return myCacheEntries[iter->second];
                                    }

private:
    static CacheEntry           theDefaultCacheEntry;

    UT_Array<CacheEntry>        myCacheEntries;
    UT_ArrayMap<const PDG_WorkItem*, exint>
                                myCacheMap;
};

#endif