BitmapFromBinary.java

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

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.AlwaysNullable;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.functions.PropagateNullLiteral;
import org.apache.doris.nereids.trees.expressions.shape.UnaryExpression;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.BitmapType;
import org.apache.doris.nereids.types.VarBinaryType;

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

import java.util.List;

/**
 * ScalarFunction 'bitmap_from_binary'.
 *
 * <p>Converts Doris serialized bitmap bytes (the format produced by {@code bitmap_to_binary},
 * by the hive-udf to_bitmap/bitmap_union UDAFs, or by Spark load) into a BITMAP. The input
 * is a VARBINARY value, typically a hive BINARY column read through a catalog with
 * {@code enable.mapping.varbinary=true}. Invalid or truncated bytes yield NULL.
 */
public class BitmapFromBinary extends ScalarFunction
        implements UnaryExpression, ExplicitlyCastableSignature, AlwaysNullable, PropagateNullLiteral {

    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.ret(BitmapType.INSTANCE).args(VarBinaryType.MAX_VARBINARY_TYPE)
    );

    /**
     * constructor with 1 argument.
     */
    public BitmapFromBinary(Expression arg) {
        super("bitmap_from_binary", arg);
    }

    /** constructor for withChildren and reuse signature */
    private BitmapFromBinary(ScalarFunctionParams functionParams) {
        super(functionParams);
    }

    /**
     * withChildren.
     */
    @Override
    public BitmapFromBinary withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() == 1);
        return new BitmapFromBinary(getFunctionParams(children));
    }

    @Override
    public List<FunctionSignature> getSignatures() {
        return SIGNATURES;
    }

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