CreateMap.java

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// to you under the Apache License, Version 2.0 (the
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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.AlwaysNotNullable;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
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.util.TypeCoercionUtils;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

import java.util.ArrayList;
import java.util.List;

/**
 * ScalarFunction 'map'.
 */
public class CreateMap extends ScalarFunction
        implements ExplicitlyCastableSignature, AlwaysNotNullable {

    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.ret(MapType.SYSTEM_DEFAULT).args()
    );

    /**
     * constructor with 0 or more arguments.
     */
    public CreateMap(Expression... varArgs) {
        super("map", varArgs);
    }

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

    @Override
    public DataType getDataType() {
        if (arity() >= 2) {
            // use Array function to get the common key and value type
            // first collect all key types in odd position, and value types in even position
            // then get the common type of key and value
            List<Expression> keyExpressions = new ArrayList<>();
            List<Expression> valueExpressions = new ArrayList<>();
            for (int i = 0; i < children.size(); i++) {
                if (i % 2 == 0) {
                    keyExpressions.add(children.get(i));
                } else {
                    valueExpressions.add(children.get(i));
                }
            }
            Array keyArr = new Array(keyExpressions);
            DataType keyType = ((ArrayType) keyArr.getDataType()).getItemType();
            Array valueArr = new Array(valueExpressions);
            DataType valueType = ((ArrayType) valueArr.getDataType()).getItemType();
            return MapType.of(keyType, valueType);
        }
        return MapType.SYSTEM_DEFAULT;
    }

    @Override
    public void checkLegalityBeforeTypeCoercion() {
        if (arity() % 2 != 0) {
            throw new AnalysisException("map can't be odd parameters, need even parameters " + this.toSql());
        }
        children.forEach(child -> {
            if (child.getDataType().isJsonType() || child.getDataType().isVariantType()) {
                throw new AnalysisException("map does not support jsonb/variant type");
            }
        });
    }

    /**
     * withChildren.
     */
    @Override
    public CreateMap withChildren(List<Expression> children) {
        return new CreateMap(getFunctionParams(children));
    }

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

    @Override
    public List<FunctionSignature> getSignatures() {
        if (arity() == 0) {
            return SIGNATURES;
        } else {
            List<Expression> keys = Lists.newArrayList();
            List<Expression> values = Lists.newArrayList();
            for (int i = 0; i < arity(); i++) {
                if (i % 2 == 0) {
                    keys.add(child(i));
                } else {
                    values.add(child(i));
                }
            }
            // TODO: use the find common type to get key and value type after we redefine type coercion in Doris.
            Array keyArray = new Array(keys.toArray(new Expression[0]));
            Array valueArray = new Array(values.toArray(new Expression[0]));
            keyArray = (Array) TypeCoercionUtils.implicitCastInputTypes(keyArray, keyArray.expectedInputTypes());
            valueArray = (Array) TypeCoercionUtils.implicitCastInputTypes(valueArray, valueArray.expectedInputTypes());
            DataType keyType = ((ArrayType) (keyArray.getDataType())).getItemType();
            DataType valueType = ((ArrayType) (valueArray.getDataType())).getItemType();
            ImmutableList.Builder<DataType> childTypes = ImmutableList.builder();
            for (int i = 0; i < arity(); i++) {
                if (i % 2 == 0) {
                    childTypes.add(keyType);
                } else {
                    childTypes.add(valueType);
                }
            }
            return ImmutableList.of(FunctionSignature.of(
                    getDataType(),
                    childTypes.build())
            );
        }
    }

    @Override
    public FunctionSignature computeSignature(FunctionSignature signature) {
        return signature;
    }
}