org.apache.blur.utils.ResetableDocumentStoredFieldVisitor.java Source code

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Here is the source code for org.apache.blur.utils.ResetableDocumentStoredFieldVisitor.java

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package org.apache.blur.utils;

/*
 * 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.
 */

import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.document.StoredField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.FieldInfo;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.StoredFieldVisitor;

/**
 * A {@link StoredFieldVisitor} that creates a {@link Document} containing all
 * stored fields, or only specific requested fields provided to
 * {@link #DocumentStoredFieldVisitor(Set)}.
 * <p>
 * This is used by {@link IndexReader#document(int)} to load a document.
 * 
 * @lucene.experimental
 */

public class ResetableDocumentStoredFieldVisitor extends StoredFieldVisitor {

    private static final int _emptyDocumentSize;
    private static final int _integerFieldSize;
    private static final int _longFieldSize;
    private static final int _doubleFieldSize;
    private static final int _floatFieldSize;
    private static final int _emptyString;
    private static final int _emptyByteArrayFieldSize;

    static {
        _emptyDocumentSize = (int) RamUsageEstimator.sizeOf(new Document());
        _integerFieldSize = (int) RamUsageEstimator.sizeOf(new StoredField("", 0));
        _longFieldSize = (int) RamUsageEstimator.sizeOf(new StoredField("", 0l));
        _doubleFieldSize = (int) RamUsageEstimator.sizeOf(new StoredField("", 0.0));
        _floatFieldSize = (int) RamUsageEstimator.sizeOf(new StoredField("", 0.0f));
        _emptyByteArrayFieldSize = (int) RamUsageEstimator.sizeOf(new StoredField("", new byte[] {}));
        _emptyString = (int) RamUsageEstimator.sizeOf("");
    }

    private Document doc = new Document();
    private final Set<String> fieldsToAdd;
    private int size = _emptyDocumentSize;

    /** Load only fields named in the provided <code>Set&lt;String&gt;</code>. */
    public ResetableDocumentStoredFieldVisitor(Set<String> fieldsToAdd) {
        this.fieldsToAdd = fieldsToAdd;
    }

    /** Load only fields named in the provided <code>Set&lt;String&gt;</code>. */
    public ResetableDocumentStoredFieldVisitor(String... fields) {
        fieldsToAdd = new HashSet<String>(fields.length);
        for (String field : fields) {
            fieldsToAdd.add(field);
        }
    }

    /** Load all stored fields. */
    public ResetableDocumentStoredFieldVisitor() {
        this.fieldsToAdd = null;
    }

    @Override
    public void binaryField(FieldInfo fieldInfo, byte[] value) throws IOException {
        doc.add(new StoredField(fieldInfo.name, value));
        addSize(fieldInfo, _emptyByteArrayFieldSize);
        size += value.length;
    }

    @Override
    public void stringField(FieldInfo fieldInfo, String value) throws IOException {
        final FieldType ft = new FieldType(TextField.TYPE_STORED);
        ft.setStoreTermVectors(fieldInfo.hasVectors());
        ft.setIndexed(fieldInfo.isIndexed());
        ft.setOmitNorms(fieldInfo.omitsNorms());
        ft.setIndexOptions(fieldInfo.getIndexOptions());
        doc.add(new Field(fieldInfo.name, value, ft));
        size += _emptyString * 2;
        size += fieldInfo.name.length() * 2;
        size += value.length() * 2;
    }

    @Override
    public void intField(FieldInfo fieldInfo, int value) {
        doc.add(new StoredField(fieldInfo.name, value));
        addSize(fieldInfo, _integerFieldSize);
    }

    @Override
    public void longField(FieldInfo fieldInfo, long value) {
        doc.add(new StoredField(fieldInfo.name, value));
        addSize(fieldInfo, _longFieldSize);
    }

    @Override
    public void floatField(FieldInfo fieldInfo, float value) {
        doc.add(new StoredField(fieldInfo.name, value));
        addSize(fieldInfo, _floatFieldSize);
    }

    @Override
    public void doubleField(FieldInfo fieldInfo, double value) {
        doc.add(new StoredField(fieldInfo.name, value));
        addSize(fieldInfo, _doubleFieldSize);
    }

    private void addSize(FieldInfo fieldInfo, int fieldSize) {
        size += fieldSize;
        size += _emptyString;
        size += fieldInfo.name.length() * 2;
    }

    @Override
    public Status needsField(FieldInfo fieldInfo) throws IOException {
        return fieldsToAdd == null || fieldsToAdd.contains(fieldInfo.name) ? Status.YES : Status.NO;
    }

    /**
     * Retrieve the visited document.
     * 
     * @return Document populated with stored fields. Note that only the stored
     *         information in the field instances is valid, data such as boosts,
     *         indexing options, term vector options, etc is not set.
     */
    public Document getDocument() {
        return doc;
    }

    public int getSize() {
        return size;
    }

    public void reset() {
        doc = new Document();
        size = _emptyDocumentSize;
    }
}