com.cloudera.impala.analysis.CollectionStructType.java Source code

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Here is the source code for com.cloudera.impala.analysis.CollectionStructType.java

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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package com.cloudera.impala.analysis;

import java.util.ArrayList;

import jline.internal.Preconditions;

import com.cloudera.impala.catalog.ArrayType;
import com.cloudera.impala.catalog.MapType;
import com.cloudera.impala.catalog.ScalarType;
import com.cloudera.impala.catalog.StructField;
import com.cloudera.impala.catalog.StructType;
import com.cloudera.impala.catalog.Type;
import com.google.common.collect.Lists;

/**
 * Generated struct type describing the fields of a collection type
 * that can be referenced in paths.
 *
 * Parent Type      CollectionStructType
 * array<i>    -->  struct<item:i,pos:bigint>
 * map<k,v>    -->  struct<key:k,value:v>
 */
public class CollectionStructType extends StructType {
    // True if this struct describes the fields of a map,
    // false if it describes the fields of an array.
    private final boolean isMapStruct_;

    // Field that can be skipped by implicit paths if its type is a struct.
    private final StructField optionalField_;

    private CollectionStructType(ArrayList<StructField> fields, boolean isMapStruct) {
        super(fields);
        isMapStruct_ = isMapStruct;
        if (isMapStruct_) {
            optionalField_ = getField(Path.MAP_VALUE_FIELD_NAME);
        } else {
            optionalField_ = getField(Path.ARRAY_ITEM_FIELD_NAME);
        }
        Preconditions.checkNotNull(optionalField_);
    }

    public static CollectionStructType createArrayStructType(ArrayType arrayType) {
        Type itemType = arrayType.getItemType();
        ArrayList<StructField> fields = Lists.newArrayListWithCapacity(2);
        // The item field name comes before the pos field name so that a path to the
        // stored item corresponds to its physical path.
        fields.add(new StructField(Path.ARRAY_ITEM_FIELD_NAME, itemType));
        fields.add(new StructField(Path.ARRAY_POS_FIELD_NAME, ScalarType.BIGINT));
        return new CollectionStructType(fields, false);
    }

    public static CollectionStructType createMapStructType(MapType mapType) {
        ArrayList<StructField> mapFields = Lists.newArrayListWithCapacity(2);
        mapFields.add(new StructField(Path.MAP_KEY_FIELD_NAME, mapType.getKeyType()));
        mapFields.add(new StructField(Path.MAP_VALUE_FIELD_NAME, mapType.getValueType()));
        return new CollectionStructType(mapFields, true);
    }

    public StructField getOptionalField() {
        return optionalField_;
    }

    public boolean isMapStruct() {
        return isMapStruct_;
    }

    public boolean isArrayStruct() {
        return !isMapStruct_;
    }
}