MapFromArrays.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.PreferPushDownProject;
import org.apache.doris.nereids.trees.expressions.functions.ComputePrecision;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
import org.apache.doris.nereids.trees.expressions.shape.BinaryExpression;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.ArrayType;
import org.apache.doris.nereids.types.DataType;
import org.apache.doris.nereids.types.MapType;
import org.apache.doris.nereids.types.NullType;
import org.apache.doris.nereids.types.TinyIntType;
import org.apache.doris.nereids.types.coercion.AnyDataType;
import org.apache.doris.nereids.types.coercion.FollowToAnyDataType;
import org.apache.doris.nereids.util.TypeCoercionUtils;

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

import java.util.List;

/** Construct a Map from key and value arrays with identical per-row offsets. */
public class MapFromArrays extends ScalarFunction
        implements BinaryExpression, ComputePrecision, ExplicitlyCastableSignature, PropagateNullable,
        PreferPushDownProject {

    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.ret(MapType.of(new FollowToAnyDataType(0), new FollowToAnyDataType(1)))
                    .args(ArrayType.of(new AnyDataType(0)), ArrayType.of(new AnyDataType(1))));

    public MapFromArrays(Expression keys, Expression values) {
        super("map_from_arrays", keys, values);
    }

    private MapFromArrays(ScalarFunctionParams functionParams) {
        super(functionParams);
    }

    @Override
    public MapFromArrays withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() == 2);
        return new MapFromArrays(getFunctionParams(children));
    }

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

    /**
     * Keep the resolved key and value types independent. The default precision promotion merges
     * decimal and time types from all arguments, which can lose precision across the two map sides.
     */
    @Override
    public FunctionSignature computePrecision(FunctionSignature signature) {
        return signature;
    }

    @Override
    public FunctionSignature computeSignature(FunctionSignature signature) {
        FunctionSignature resolvedSignature = super.computeSignature(signature);
        DataType returnType = TypeCoercionUtils.replaceSpecifiedType(
                resolvedSignature.returnType, NullType.class, TinyIntType.INSTANCE);
        FunctionSignature normalizedSignature = resolvedSignature
                .withArgumentTypes(getArguments(), (index, argumentType, argument) ->
                        TypeCoercionUtils.replaceSpecifiedType(
                                argumentType, NullType.class, TinyIntType.INSTANCE))
                .withReturnType(returnType);
        normalizedSignature.returnType.validateDataType();
        return normalizedSignature;
    }

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