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A record-oriented layer built for FoundationDB (proto2).
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/*
 * AndOrComponent.java
 *
 * This source file is part of the FoundationDB open source project
 *
 * Copyright 2015-2018 Apple Inc. and the FoundationDB project authors
 *
 * Licensed 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 com.apple.foundationdb.record.query.expressions;

import com.apple.foundationdb.annotation.API;
import com.apple.foundationdb.record.EvaluationContext;
import com.apple.foundationdb.record.provider.foundationdb.FDBRecord;
import com.apple.foundationdb.record.provider.foundationdb.FDBRecordStoreBase;
import com.apple.foundationdb.record.query.plan.temp.ExpressionRef;
import com.apple.foundationdb.record.query.plan.temp.NestedContext;
import com.google.common.collect.ImmutableList;
import com.google.protobuf.Message;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.function.Function;

/**
 * The common base class for Boolean {@code And} and {@code Or} query components.
 */
@API(API.Status.INTERNAL)
public abstract class AndOrComponent extends SimpleComponentWithChildren implements ComponentWithChildren {

    protected abstract boolean isOr();

    public AndOrComponent(@Nonnull List> operands) {
        super(operands);
    }

    @Nullable
    private Boolean evalInternal(@Nonnull Function evalChildFunction) {
        Boolean retVal = !isOr();
        for (QueryComponent child : getChildren()) {
            final Boolean val = evalChildFunction.apply(child);
            if (val == null) {
                retVal = null;
            } else if (val) {
                if (isOr()) {
                    return true;
                }
            } else {
                if (!isOr()) {
                    return false;
                }
            }
        }
        return retVal;
    }

    @Nullable
    @Override
    public  Boolean evalMessage(@Nonnull FDBRecordStoreBase store, @Nonnull EvaluationContext context,
                                                   @Nullable FDBRecord record, @Nullable Message message) {
        return evalInternal(child -> (child.evalMessage(store, context, record, message)));
    }

    @Nonnull
    @Override
    public  CompletableFuture evalMessageAsync(@Nonnull FDBRecordStoreBase store, @Nonnull EvaluationContext context,
                                                                           @Nullable FDBRecord record, @Nullable Message message) {
        return new AsyncBoolean<>(isOr(), getChildren(), store, context, record, message).eval();
    }

    @Override
    public boolean isAsync() {
        return getChildren().stream().anyMatch(QueryComponent::isAsync);
    }

    @Nullable
    @Override
    @API(API.Status.EXPERIMENTAL)
    public ExpressionRef asNestedWith(@Nonnull NestedContext nestedContext,
                                                      @Nonnull ExpressionRef thisRef) {
        // An AndComponent has an exactly equivalent form within a NestedContext if and only if all of its children are
        // nested under the context's parent.
        if (nestedContext.isParentFieldFannedOut()) {
            // If the parent field is fanned out, then we can only place a single conjunct in the context even if all
            // of them share a common parent because each separate fan out iterates through the repeated children
            // independently. Concretely, the expressions
            //     and(field("p", FanType.FanOut).matches(field("a").equals("foo")),
            //         field("p", FanType.Fanout).matches(field("b").equals("bar")))
            // and
            //     field("p", FanType.FanOut).matches(and(field("a").equals("foo"), field("b").equals("bar")))
            // are not the same.
            return null;
        }
        ImmutableList.Builder> operandRefs = ImmutableList.builder();
        for (ExpressionRef operandRef : getChildrenRefs()) {
            final ExpressionRef nestedOperandRef = nestedContext.getNestedQueryComponent(operandRef);
            if (nestedOperandRef == null) {
                return null;
            }
            operandRefs.add(nestedOperandRef);
        }
        return thisRef.getNewRefWith(new AndComponent(operandRefs.build()));
    }

    @Nonnull
    @Override
    @API(API.Status.EXPERIMENTAL)
    public ExpressionRef asUnnestedWith(@Nonnull NestedContext nestedContext,
                                                        @Nonnull ExpressionRef thisRef) {
        return BaseField.unnestedWith(nestedContext, thisRef);
    }
}