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    • com.bazaarvoice.emodb.sor.condition.impl.OrConditionBuilderImpl Maven / Gradle / Ivy

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    package com.bazaarvoice.emodb.sor.condition.impl;

import com.bazaarvoice.emodb.common.json.OrderedJson;
import com.bazaarvoice.emodb.sor.condition.Condition;
import com.bazaarvoice.emodb.sor.condition.Conditions;
import com.bazaarvoice.emodb.sor.condition.ConstantCondition;
import com.bazaarvoice.emodb.sor.condition.EqualCondition;
import com.bazaarvoice.emodb.sor.condition.InCondition;
import com.bazaarvoice.emodb.sor.condition.IntrinsicCondition;
import com.bazaarvoice.emodb.sor.condition.OrCondition;
import com.bazaarvoice.emodb.sor.condition.OrConditionBuilder;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Lists;

import java.util.Collection;
import java.util.List;
import java.util.Map;

public class OrConditionBuilderImpl implements OrConditionBuilder {

    private List _conditions;
    private List _values;
    private ListMultimap _intrinsics;
    private boolean _alwaysTrue;

    @Override
    public OrConditionBuilder or(Condition condition) {
        // OR conditions are inherently O(n).  There are a few patterns (eg. Polloi subscriptions) that can lead to
        // long lists of OR conditions and it's worth it to try to convert those conditions to more efficient O(1)
        // lookups using sets.  The optimizations performed here include:
        // 1.  or(..., alwaysTrue(), ...) => alwaysTrue()                     (rare)
        // 2.  or(..., alwaysFalse(), ...) => or(..., ...)                    (rare)
        // 3.  or(equal(val1), equal(val2), ...) => or(in(val1, val2), ...)   (classic O(n) lookup converted to O(1))
        // 4.  or(intrinsic(name:val1), intrinsic(name:val2), ...) =>
        //            or(intrinsic(name:val1,val2), ...)                      (intrinsic O(n) lookup converted to O(1))
        // 5.  or(..., or(...), ...) => or(..., ... ,...)           (flatten OR to increase optimization opportunities)
        //
        // Polloi uses the 4th form.  That's the optimization that has the biggest impact.

        if (condition instanceof ConstantCondition) {
            if (((ConstantCondition) condition).getValue()) {
                _alwaysTrue = true;
            }
            // else ignore alwaysFalse()

        } else if (condition instanceof EqualCondition) {
            if (_values == null) {
                _values = Lists.newArrayList();
            }
            _values.add(((EqualCondition) condition).getValue());

        } else if (condition instanceof InCondition) {
            if (_values == null) {
                _values = Lists.newArrayList();
            }
            _values.addAll(((InCondition) condition).getValues());

        } else if (condition instanceof IntrinsicCondition) {
            if (_intrinsics == null) {
                _intrinsics = ArrayListMultimap.create();
            }
            IntrinsicCondition intrinsic = (IntrinsicCondition) condition;
            _intrinsics.put(intrinsic.getName(), intrinsic.getCondition());

        } else if (condition instanceof OrCondition) {
            orAny(((OrCondition) condition).getConditions());

        } else {
            if (_conditions == null) {
                _conditions = Lists.newArrayList();
            }
            _conditions.add(condition);
        }
        return this;
    }

    public OrConditionBuilder orAny(Collection conditions) {
        for (Condition condition : conditions) {
            or(condition);
        }
        return this;
    }

    @Override
    public Condition build() {
        if (_alwaysTrue) {
            return Conditions.alwaysTrue();
        }

        List conditions = Lists.newArrayList();
        if (_values != null) {
            conditions.add(Conditions.in(_values));
        }
        if (_intrinsics != null) {
            for (Map.Entry> entry :
                    OrderedJson.ENTRY_COMPARATOR.immutableSortedCopy(_intrinsics.asMap().entrySet())) {
                conditions.add(Conditions.intrinsic(entry.getKey(), Conditions.or(entry.getValue())));
            }
        }
        if (_conditions != null) {
            conditions.addAll(_conditions);
        }

        if (conditions.isEmpty()) {
            return Conditions.alwaysFalse();
        } else if (conditions.size() == 1) {
            return conditions.get(0);
        } else {
            return new OrConditionImpl(conditions);
        }
    }
}
    
    
    
    

    




    
    
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