JsonMergePatch.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.AlwaysNullable;
import org.apache.doris.nereids.trees.expressions.functions.CustomSignature;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.DataType;
import org.apache.doris.nereids.types.VarcharType;
import org.apache.doris.nereids.util.ExpressionUtils;

import com.google.common.base.Preconditions;

import java.util.ArrayList;
import java.util.List;

/**
 * ScalarFunction json_merge_patch
 */
public class JsonMergePatch extends ScalarFunction implements CustomSignature, AlwaysNullable {

    /**
     * constructor with 2 or more arguments.
     */
    public JsonMergePatch(Expression arg0, Expression arg1, Expression... varArgs) {
        super("json_merge_patch", ExpressionUtils.mergeArguments(arg0, arg1, varArgs));
    }

    @Override
    public FunctionSignature customSignature() {
        List<DataType> arguments = new ArrayList<>();
        for (int i = 0; i < arity(); i++) {
            arguments.add(VarcharType.SYSTEM_DEFAULT);
        }
        return FunctionSignature.of(VarcharType.SYSTEM_DEFAULT, arguments);
    }

    /**
     * withChildren.
     */
    @Override
    public JsonMergePatch withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() >= 2);
        return new JsonMergePatch(children.get(0), children.get(1),
            children.subList(2, children.size()).toArray(new Expression[0]));
    }

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