Ndv.java

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

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.catalog.Type;
import org.apache.doris.nereids.exceptions.AnalysisException;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.functions.Function;
import org.apache.doris.nereids.trees.expressions.literal.BigIntLiteral;
import org.apache.doris.nereids.trees.expressions.shape.UnaryExpression;
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 com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * AggregateFunction 'ndv'. This class is generated by GenserateFunction.
 */
public class Ndv extends NotNullableAggregateFunction
        implements UnaryExpression, ExplicitlyCastableSignature, RollUpTrait {

    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.ret(BigIntType.INSTANCE).args(AnyDataType.INSTANCE_WITHOUT_INDEX)
    );

    /**
     * constructor with 1 argument.
     */
    public Ndv(Expression arg) {
        super("ndv", arg);
    }

    public Ndv(boolean distinct, Expression arg) {
        this(arg);
    }

    @Override
    public void checkLegalityBeforeTypeCoercion() {
        if (getArgumentType(0).isOnlyMetricType()) {
            throw new AnalysisException(Type.OnlyMetricTypeErrorMsg);
        }
    }

    /**
     * withDistinctAndChildren.
     */
    @Override
    public Ndv withDistinctAndChildren(boolean distinct, List<Expression> children) {
        Preconditions.checkArgument(children.size() == 1);
        return new Ndv(children.get(0));
    }

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

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

    @Override
    public Function constructRollUp(Expression param, Expression... varParams) {
        return new HllUnionAgg(param);
    }

    @Override
    public boolean canRollUp() {
        return false;
    }

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