ArrayZip.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.exceptions.AnalysisException;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.ChildDerivedSignature;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.functions.ExpressionTrait;
import org.apache.doris.nereids.trees.expressions.functions.PreserveChildTypePrecision;
import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
import org.apache.doris.nereids.trees.expressions.functions.SearchSignature;
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.StructField;
import org.apache.doris.nereids.types.StructType;
import org.apache.doris.nereids.types.TinyIntType;
import org.apache.doris.nereids.util.ExpressionUtils;

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

import java.util.List;

/**
 * ScalarFunction 'array_zip'.
 */
public class ArrayZip extends ScalarFunction implements ExplicitlyCastableSignature,
        PropagateNullable, ChildDerivedSignature, PreserveChildTypePrecision {

    /**
     * constructor with more than 0 arguments.
     */
    public ArrayZip(Expression arg, Expression ...varArgs) {
        super("array_zip", ExpressionUtils.mergeArguments(arg, varArgs));
    }

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

    /**
     * withChildren.
     */
    @Override
    public ArrayZip withChildren(List<Expression> children) {
        Preconditions.checkArgument(!children.isEmpty());
        return new ArrayZip(getFunctionParams(children));
    }

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

    @Override
    public List<FunctionSignature> getSignatures() {
        if (children.isEmpty()) {
            SearchSignature.throwCanNotFoundFunctionException(getName(), getArguments());
        }
        if (!children.stream()
                .map(ExpressionTrait::getDataType)
                .filter(dt -> !dt.isNullType())
                .allMatch(ArrayType.class::isInstance)) {
            SearchSignature.throwCanNotFoundFunctionException(getName(), getArguments());
        }
        ImmutableList.Builder<StructField> structFieldBuilder = ImmutableList.builder();
        for (int i = 0; i < children.size(); i++) {
            DataType itemType = TinyIntType.INSTANCE;
            DataType childType = children.get(i).getDataType();
            if (childType instanceof ArrayType) {
                itemType = ((ArrayType) childType).getItemType();
            }
            structFieldBuilder.add(new StructField(StructField.DEFAULT_FIELD_NAME + (i + 1), itemType, true, ""));
        }

        return ImmutableList.of(FunctionSignature.ret(ArrayType.of(new StructType(structFieldBuilder.build())))
                .args(children.stream().map(ExpressionTrait::getDataType).toArray(DataType[]::new)));
    }

    @Override
    public FunctionSignature deriveSignatureFromChildren(
            FunctionSignature resolvedSignature, List<Expression> immediateOriginArguments) {
        int argumentCount = children.size();
        ImmutableList.Builder<DataType> argumentTypes = ImmutableList.builderWithExpectedSize(argumentCount);
        ImmutableList.Builder<StructField> structFields = ImmutableList.builderWithExpectedSize(argumentCount);
        for (int i = 0; i < argumentCount; i++) {
            DataType currentType = getArgument(i).getDataType();
            if (!(currentType instanceof ArrayType) && !currentType.isNullType()) {
                throw new AnalysisException(
                        "Cannot safely reuse array_zip signature with a non-array argument");
            }
            // A newly added array has no prior item binding. Existing positions must retain theirs.
            boolean existingPosition = i < immediateOriginArguments.size();
            DataType resolvedType = existingPosition ? resolvedSignature.getArgType(i) : currentType;
            DataType originType = existingPosition
                    ? immediateOriginArguments.get(i).getDataType() : currentType;
            DataType argumentType = ChildDerivedSignature.refreshNestedTypeMetadata(
                    resolvedType, currentType, originType);
            argumentTypes.add(argumentType);
            DataType itemType = argumentType instanceof ArrayType
                    ? ((ArrayType) argumentType).getItemType() : TinyIntType.INSTANCE;
            structFields.add(new StructField(StructField.DEFAULT_FIELD_NAME + (i + 1), itemType, true, ""));
        }
        return FunctionSignature.of(ArrayType.of(new StructType(structFields.build())), argumentTypes.build());
    }
}