001/*
002 * Copyright (c) 2015-2020, Oracle and/or its affiliates. All rights reserved.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.tribuo.data.columnar.extractors;
018
019import com.oracle.labs.mlrg.olcut.provenance.ConfiguredObjectProvenance;
020import com.oracle.labs.mlrg.olcut.provenance.impl.ConfiguredObjectProvenanceImpl;
021
022import java.util.Optional;
023import java.util.logging.Logger;
024
025/**
026 * Extracts the field value and emits it as a String.
027 */
028public class IdentityExtractor extends SimpleFieldExtractor<String> {
029    private static final Logger logger = Logger.getLogger(IdentityExtractor.class.getName());
030
031    /**
032     * Extracts the String value from the supplied field.
033     * Writes the metadata out using the field name as the key.
034     * @param fieldName The field name to inspect.
035     */
036    public IdentityExtractor(String fieldName) {
037        super(fieldName);
038    }
039
040    /**
041     * Extracts the String value from the supplied field.
042     * Writes the metadata out using the metadataName as the key.
043     * @param fieldName The field name to inspect.
044     * @param metadataName The metadata name to emit.
045     */
046    public IdentityExtractor(String fieldName, String metadataName) {
047        super(fieldName, metadataName);
048    }
049
050    /**
051     * For olcut.
052     */
053    private IdentityExtractor() {}
054
055    @Override
056    public Class<String> getValueType() {
057        return String.class;
058    }
059
060    @Override
061    protected Optional<String> extractField(String value) {
062        if (value == null || value.isEmpty()) {
063            return Optional.empty();
064        } else {
065            return Optional.of(value);
066        }
067    }
068
069    @Override
070    public ConfiguredObjectProvenance getProvenance() {
071        return new ConfiguredObjectProvenanceImpl(this,"FieldExtractor");
072    }
073}