MultiDistinctCount.java

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package org.apache.doris.nereids.trees.expressions.functions.agg;

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.nereids.analyzer.Unbound;
import org.apache.doris.nereids.trees.expressions.Cast;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.literal.BigIntLiteral;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.BigIntType;
import org.apache.doris.nereids.types.coercion.AnyDataType;
import org.apache.doris.nereids.types.coercion.DateLikeType;
import org.apache.doris.nereids.util.ExpressionUtils;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;

import java.util.List;

/** MultiDistinctCount */
public class MultiDistinctCount extends NotNullableAggregateFunction
        implements ExplicitlyCastableSignature, MultiDistinction {
    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.ret(BigIntType.INSTANCE).varArgs(AnyDataType.INSTANCE_WITHOUT_INDEX)
    );
    private final boolean mustUseMultiDistinctAgg;

    // MultiDistinctCount is created in AggregateStrategies phase
    // can't change getSignatures to use type coercion rule to add a cast expr
    // because AggregateStrategies phase is after type coercion
    public MultiDistinctCount(Expression arg0, Expression... varArgs) {
        this(false, arg0, varArgs);
    }

    public MultiDistinctCount(boolean distinct, Expression arg0, Expression... varArgs) {
        this(false, false, ExpressionUtils.mergeArguments(arg0, varArgs));
    }

    private MultiDistinctCount(boolean mustUseMultiDistinctAgg, boolean distinct, List<Expression> children) {
        super("multi_distinct_count", false, children
                .stream()
                .map(arg -> !(arg instanceof Unbound) && arg.getDataType() instanceof DateLikeType
                        ? new Cast(arg, BigIntType.INSTANCE) : arg)
                .collect(ImmutableList.toImmutableList()));
        this.mustUseMultiDistinctAgg = mustUseMultiDistinctAgg;
    }

    @Override
    public MultiDistinctCount withDistinctAndChildren(boolean distinct, List<Expression> children) {
        Preconditions.checkArgument(children.size() > 0);
        return new MultiDistinctCount(mustUseMultiDistinctAgg, distinct, children);
    }

    @Override
    public <R, C> R accept(ExpressionVisitor<R, C> visitor, C context) {
        return visitor.visitMultiDistinctCount(this, context);
    }

    @Override
    public List<FunctionSignature> getSignatures() {
        return SIGNATURES;
    }

    @Override
    public boolean mustUseMultiDistinctAgg() {
        return mustUseMultiDistinctAgg;
    }

    @Override
    public Expression withMustUseMultiDistinctAgg(boolean mustUseMultiDistinctAgg) {
        return new MultiDistinctCount(mustUseMultiDistinctAgg, false, children);
    }

    @Override
    public Expression resultForEmptyInput() {
        return new BigIntLiteral(0);
    }
}