Divide.java

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// to you under the Apache License, Version 2.0 (the
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//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.doris.nereids.trees.expressions;

import org.apache.doris.analysis.ArithmeticExpr.Operator;
import org.apache.doris.common.Config;
import org.apache.doris.nereids.exceptions.UnboundException;
import org.apache.doris.nereids.trees.expressions.functions.AlwaysNullable;
import org.apache.doris.nereids.trees.expressions.functions.PropagateNullLiteral;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.DataType;
import org.apache.doris.nereids.types.DecimalV3Type;
import org.apache.doris.nereids.types.DoubleType;
import org.apache.doris.qe.ConnectContext;

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

import java.util.List;

/**
 * Divide Expression.
 */
public class Divide extends BinaryArithmetic implements AlwaysNullable, PropagateNullLiteral {

    public Divide(Expression left, Expression right) {
        super(ImmutableList.of(left, right), Operator.DIVIDE);
    }

    private Divide(List<Expression> children) {
        super(children, Operator.DIVIDE);
    }

    @Override
    public Expression withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() == 2);
        return new Divide(children);
    }

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

    @Override
    public DataType getDataType() throws UnboundException {
        if (left().getDataType().isDecimalV3Type()) {
            DecimalV3Type dt1 = (DecimalV3Type) left().getDataType();
            DecimalV3Type dt2 = (DecimalV3Type) right().getDataType();
            return DecimalV3Type.createDecimalV3Type(dt1.getPrecision(), dt1.getScale() - dt2.getScale());
        }
        return super.getDataType();
    }

    @Override
    public DecimalV3Type getDataTypeForDecimalV3(DecimalV3Type t1, DecimalV3Type t2) {
        int precision = t1.getPrecision() + t2.getScale() + Config.div_precision_increment;
        int scale = t1.getScale();
        boolean enableDecimal256 = false;
        int defaultScale = 6;
        ConnectContext connectContext = ConnectContext.get();
        if (connectContext != null) {
            enableDecimal256 = connectContext.getSessionVariable().isEnableDecimal256();
            defaultScale = connectContext.getSessionVariable().decimalOverflowScale;
        }
        if (enableDecimal256 && precision > DecimalV3Type.MAX_DECIMAL256_PRECISION) {
            int integralPartBoundary = DecimalV3Type.MAX_DECIMAL256_PRECISION - defaultScale;
            if (precision - scale < integralPartBoundary) {
                // retains more int part
                scale = DecimalV3Type.MAX_DECIMAL256_PRECISION - (precision - scale);
            } else if (precision - scale > integralPartBoundary && scale < defaultScale) {
                // scale not change, retains more scale part
            } else {
                scale = defaultScale;
            }
            precision = DecimalV3Type.MAX_DECIMAL256_PRECISION;
        } else if (!enableDecimal256 && precision > DecimalV3Type.MAX_DECIMAL128_PRECISION) {
            int integralPartBoundary = DecimalV3Type.MAX_DECIMAL128_PRECISION - defaultScale;
            if (precision - scale < integralPartBoundary) {
                // retains more int part
                scale = DecimalV3Type.MAX_DECIMAL128_PRECISION - (precision - scale);
            } else if (precision - scale > integralPartBoundary && scale < defaultScale) {
                // scale not change, retains more scale part
            } else {
                scale = defaultScale;
            }
            precision = DecimalV3Type.MAX_DECIMAL128_PRECISION;
        }
        scale = Math.min(precision, scale + t2.getScale() + Config.div_precision_increment);
        return DecimalV3Type.createDecimalV3Type(precision, scale);
    }

    @Override
    public DataType getDataTypeForOthers(DataType t1, DataType t2) {
        return DoubleType.INSTANCE;
    }

    // Divide is implemented as a scalar function which return type is always nullable.
    @Override
    public boolean nullable() throws UnboundException {
        return true;
    }
}