ExplodeJsonArrayString.java

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

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
import org.apache.doris.nereids.trees.expressions.shape.UnaryExpression;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.JsonType;
import org.apache.doris.nereids.types.VarcharType;

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

import java.util.List;

/**
 * explode_json_array_string("['1', '2', '3']"), generate 3 lines include '1', '2' and '3'.
 */
public class ExplodeJsonArrayString extends TableGeneratingFunction implements UnaryExpression, PropagateNullable {

    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.ret(VarcharType.SYSTEM_DEFAULT).args(JsonType.INSTANCE),
            FunctionSignature.ret(VarcharType.SYSTEM_DEFAULT).args(VarcharType.SYSTEM_DEFAULT)
    );

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

    /**
     * withChildren.
     */
    @Override
    public ExplodeJsonArrayString withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() == 1);
        return new ExplodeJsonArrayString(children.get(0));
    }

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

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