NullSafeEqual.java

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

import org.apache.doris.nereids.trees.expressions.functions.AlwaysNotNullable;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;

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

import java.util.List;

/**
 * Null safe equal expression: a <=> b.
 * Unlike normal equal to expression, null <=> null is true.
 */
public class NullSafeEqual extends EqualPredicate implements AlwaysNotNullable {
    public NullSafeEqual(Expression left, Expression right) {
        this(left, right, false);
    }

    public NullSafeEqual(Expression left, Expression right, boolean inferred) {
        super(ImmutableList.of(left, right), "<=>", inferred);
    }

    private NullSafeEqual(List<Expression> children) {
        this(children, false);
    }

    private NullSafeEqual(List<Expression> children, boolean inferred) {
        super(children, "<=>", inferred);
    }

    @Override
    public String toString() {
        return "(" + left() + " <=> " + right() + ")";
    }

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

    @Override
    public NullSafeEqual withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() == 2);
        return new NullSafeEqual(children, this.isInferred());
    }

    @Override
    public Expression withInferred(boolean inferred) {
        return new NullSafeEqual(this.children, inferred);
    }

    @Override
    public NullSafeEqual commute() {
        return new NullSafeEqual(right(), left());
    }
}