content: /*
   * 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 org.apache.beam.examples.multilanguage.schematransforms;
  
  import static org.apache.beam.examples.multilanguage.schematransforms.ExtractWordsProvider.Configuration;
  
  import com.google.auto.service.AutoService;
  import com.google.auto.value.AutoValue;
  import java.util.Arrays;
  import java.util.List;
  import org.apache.beam.sdk.schemas.AutoValueSchema;
  import org.apache.beam.sdk.schemas.Schema;
  import org.apache.beam.sdk.schemas.annotations.DefaultSchema;
  import org.apache.beam.sdk.schemas.annotations.SchemaFieldDescription;
  import org.apache.beam.sdk.schemas.transforms.SchemaTransform;
  import org.apache.beam.sdk.schemas.transforms.SchemaTransformProvider;
  import org.apache.beam.sdk.schemas.transforms.TypedSchemaTransformProvider;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.util.Preconditions;
  import org.apache.beam.sdk.values.PCollectionRowTuple;
  import org.apache.beam.sdk.values.Row;
  
  /** Splits a line into separate words and returns each word. */
  @AutoService(SchemaTransformProvider.class)
  public class ExtractWordsProvider extends TypedSchemaTransformProvider<Configuration> {
  
    @Override
    public String identifier() {
      return "beam:schematransform:org.apache.beam:extract_words:v1";
    }
  
    @Override
    protected SchemaTransform from(Configuration configuration) {
      return new ExtractWordsTransform(configuration);
    }
  
    static class ExtractWordsTransform extends SchemaTransform {
      private static final Schema OUTPUT_SCHEMA = Schema.builder().addStringField("word").build();
      private final List<String> drop;
  
      ExtractWordsTransform(Configuration configuration) {
        this.drop = configuration.getDrop();
      }
  
      @Override
      public PCollectionRowTuple expand(PCollectionRowTuple input) {
        return PCollectionRowTuple.of(
            "output",
            input
                .getSinglePCollection()
                .apply(
                    ParDo.of(
                        new DoFn<Row, Row>() {
                          @ProcessElement
                          public void process(@Element Row element, OutputReceiver<Row> receiver) {
                            // Split the line into words.
                            String line = Preconditions.checkStateNotNull(element.getString("line"));
                            String[] words = line.split("[^\\p{L}]+", -1);
                            Arrays.stream(words)
                                .filter(w -> !drop.contains(w))
                                .forEach(
                                    word ->
                                        receiver.output(
                                            Row.withSchema(OUTPUT_SCHEMA)
                                                .withFieldValue("word", word)
                                                .build()));
                          }
                        }))
                .setRowSchema(OUTPUT_SCHEMA));
      }
    }
  
    @DefaultSchema(AutoValueSchema.class)
    @AutoValue
    public abstract static class Configuration {
      public static Builder builder() {
        return new AutoValue_ExtractWordsProvider_Configuration.Builder();
      }
  
      @SchemaFieldDescription("List of words to drop.")
      public abstract List<String> getDrop();
  
      @AutoValue.Builder
      public abstract static class Builder {
        public abstract Builder setDrop(List<String> foo);
  
        public abstract Configuration build();
      }
    }
  }
  