PropagateNullable.java

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

import org.apache.doris.nereids.trees.expressions.Expression;

import java.util.List;

/**
 * nullable is true if any children is nullable, most functions are PropagateNullable.
 *
 * e.g. `substring(null, 1)` is nullable, `substring('abc', 1)` is not nullable.
 */
public interface PropagateNullable extends ComputeNullable {
    @Override
    default boolean nullable() {
        return children().stream().anyMatch(Expression::nullable);
    }

    List<Expression> children();
}