Nvl.java

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

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.CustomSignature;
import org.apache.doris.nereids.trees.expressions.functions.SearchSignature;
import org.apache.doris.nereids.trees.expressions.shape.BinaryExpression;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.DataType;
import org.apache.doris.nereids.util.TypeCoercionUtils;

import com.google.common.base.Preconditions;

import java.util.List;
import java.util.Optional;

/**
 * ScalarFunction 'nvl'. This class is generated by GenerateFunction.
 */
public class Nvl extends ScalarFunction
        implements BinaryExpression, CustomSignature {

    /**
     * constructor with 2 arguments.
     */
    public Nvl(Expression arg0, Expression arg1) {
        super("ifnull", arg0, arg1);
    }

    /** constructor for withChildren and reuse signature */
    private Nvl(ScalarFunctionParams functionParams) {
        super(functionParams);
    }

    /**
     * custom compute nullable.
     */
    @Override
    public boolean nullable() {
        return child(0).nullable() && child(1).nullable();
    }

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

    @Override
    public FunctionSignature customSignature() {
        Optional<DataType> commonType;
        try {
            commonType = TypeCoercionUtils.findWiderTypeForTwo(getArgumentType(0), getArgumentType(1), false);
        } catch (Exception e) {
            SearchSignature.throwCanNotFoundFunctionException(this.getName(), getArguments());
            return null;
        }
        if (commonType.isPresent()) {
            return FunctionSignature.ret(commonType.get()).varArgs(commonType.get());
        } else {
            SearchSignature.throwCanNotFoundFunctionException(this.getName(), getArguments());
            return null;
        }
    }

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