JavaUdafBuilder.java

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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.doris.nereids.trees.expressions.functions.udf;

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.common.Pair;
import org.apache.doris.common.util.ReflectionUtils;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.BoundFunction;
import org.apache.doris.nereids.types.DataType;

import com.google.common.base.Suppliers;

import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;

/**
 * function builder for java udaf
 */
public class JavaUdafBuilder extends UdfBuilder {
    private final JavaUdaf udaf;
    private final int arity;
    private final boolean isVarArgs;

    public JavaUdafBuilder(JavaUdaf udaf) {
        this.udaf = udaf;
        this.isVarArgs = udaf.hasVarArguments();
        this.arity = udaf.arity();
    }

    @Override
    public List<DataType> getArgTypes() {
        return Suppliers.memoize(() -> udaf.getSignatures().get(0).argumentsTypes.stream()
                .map(DataType.class::cast)
                .collect(Collectors.toList())).get();
    }

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

    @Override
    public Class<? extends BoundFunction> functionClass() {
        return JavaUdaf.class;
    }

    @Override
    public boolean canApply(List<?> arguments) {
        if ((isVarArgs && arity > arguments.size() + 1) || (!isVarArgs && arguments.size() != arity)) {
            return false;
        }
        for (Object argument : arguments) {
            if (!(argument instanceof Expression)) {
                Optional<Class> primitiveType = ReflectionUtils.getPrimitiveType(argument.getClass());
                if (!primitiveType.isPresent() || !Expression.class.isAssignableFrom(primitiveType.get())) {
                    return false;
                }
            }
        }
        return true;
    }

    @Override
    public Pair<JavaUdaf, JavaUdaf> build(String name, List<?> arguments) {
        return Pair.ofSame((JavaUdaf) udaf.withChildren(
                arguments.stream()
                        .map(Expression.class::cast)
                        .collect(Collectors.toList()))
        );
    }

    @Override
    public String parameterDisplayString() {
        StringBuilder string = new StringBuilder("(");
        for (int i = 0; i < udaf.getArgumentsTypes().size(); ++i) {
            if (i > 0) {
                string.append(", ");
            }
            string.append(udaf.getArgumentsTypes().get(i));
            if (isVarArgs && i + 1 == udaf.getArgumentsTypes().size()) {
                string.append("...");
            }
        }
        return string.append(")").toString();
    }
}