TopNLazyExpressionEligibility.java

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package org.apache.doris.nereids.util;

import org.apache.doris.nereids.trees.expressions.Alias;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.NamedExpression;
import org.apache.doris.nereids.trees.expressions.Slot;
import org.apache.doris.nereids.trees.expressions.functions.NoneMovableFunction;
import org.apache.doris.nereids.trees.expressions.functions.scalar.L2DistanceApproximate;
import org.apache.doris.nereids.trees.expressions.functions.scalar.Score;
import org.apache.doris.nereids.trees.expressions.literal.Literal;

/** Shared expression-movement contract for logical and physical TopN lazy-materialization stages. */
public final class TopNLazyExpressionEligibility {
    private TopNLazyExpressionEligibility() {
    }

    /** Whether a named expression may be synthesized after TopN without changing query semantics. */
    public static boolean canPullAboveTopN(NamedExpression expression) {
        if (!(expression instanceof Alias)) {
            return false;
        }
        Expression child = ((Alias) expression).child();
        return !(child instanceof Slot)
                && !(child instanceof Literal)
                && !expression.anyMatch(candidate -> candidate instanceof NoneMovableFunction)
                && !expression.containsVolatileExpression()
                && !expression.anyMatch(candidate -> candidate instanceof Score)
                && !expression.anyMatch(candidate -> candidate instanceof L2DistanceApproximate);
    }
}