TernaryNode.java

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//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.doris.nereids.trees;

/**
 * interface for all tree node that have three children.
 */
public interface TernaryNode<
            NODE_TYPE extends TreeNode<NODE_TYPE>,
            FIRST_CHILD_TYPE extends TreeNode,
            SECOND_CHILD_TYPE extends TreeNode,
            THIRD_CHILD_TYPE extends TreeNode>
        extends TreeNode<NODE_TYPE> {

    default FIRST_CHILD_TYPE first() {
        return (FIRST_CHILD_TYPE) child(0);
    }

    default SECOND_CHILD_TYPE second() {
        return (SECOND_CHILD_TYPE) child(1);
    }

    default THIRD_CHILD_TYPE third() {
        return (THIRD_CHILD_TYPE) child(2);
    }

    @Override
    default int arity() {
        return 3;
    }
}