OrderKey.java

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

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

import java.util.Objects;

/**
 * Represents the order key of a statement.
 */
public class OrderKey {

    private final Expression expr;

    // Order is ascending.
    private final boolean isAsc;

    private final boolean nullFirst;

    /**
     * Constructor of OrderKey.
     *
     * @param nullFirst True if "NULLS FIRST", false if "NULLS LAST", null if not specified.
     */
    public OrderKey(Expression expr, boolean isAsc, boolean nullFirst) {
        this.expr = expr;
        this.isAsc = isAsc;
        this.nullFirst = nullFirst;
    }

    /**
     * Whether other `OrderKey` is satisfied the current `OrderKey`.
     *
     * @param other another OrderKey.
     */
    public boolean matches(OrderKey other) {
        return expr.equals(other.expr) && isAsc == other.isAsc && nullFirst == other.nullFirst;
    }

    public Expression getExpr() {
        return expr;
    }

    public boolean isAsc() {
        return isAsc;
    }

    public boolean isNullFirst() {
        return nullFirst;
    }

    public OrderKey withExpression(Expression expr) {
        return new OrderKey(expr, isAsc, nullFirst);
    }

    public String toSql() {
        return expr.toSql() + (isAsc ? " asc" : " desc") + (nullFirst ? " null first" : "");
    }

    @Override
    public String toString() {
        return expr.toString() + (isAsc ? " asc" : " desc") + (nullFirst ? " null first" : "");
    }

    @Override
    public int hashCode() {
        return Objects.hash(expr, isAsc, nullFirst);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        OrderKey that = (OrderKey) o;
        return isAsc == that.isAsc() && nullFirst == that.isNullFirst() && expr.equals(that.getExpr());
    }
}