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Modules for processing bibliographic data
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/*
 * Copyright 2016 Christoph Böhme
 *
 * Licensed 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.metafacture.biblio.pica;

import java.text.Normalizer;
import java.text.Normalizer.Form;

import org.metafacture.framework.StreamReceiver;

/**
 * Parser context for the PICA+ parser.The context implements
 * support for normalising the UTF8 encoding of values into NFC
 * on the fly and for skipping fields without any subfields.
 *
 * @author Christoph Böhme
 *
 */
final class PicaParserContext {

    private final StringBuilder builder = new StringBuilder();

    private boolean normalizeUTF8;
    private boolean skipEmptyFields = true;
    private boolean trimFieldNames = true;

    private StreamReceiver receiver;

    private String entityName;
    private boolean literalsEmitted;

    private String subfieldName;

    public void setNormalizeUTF8(final boolean normalizeUTF8) {
        this.normalizeUTF8 = normalizeUTF8;
    }

    public boolean getNormalizeUTF8() {
        return normalizeUTF8;
    }

    public void setSkipEmptyFields(final boolean skipEmptyFields) {
        this.skipEmptyFields = skipEmptyFields;
    }

    public boolean getSkipEmptyFields() {
        return skipEmptyFields;
    }

    public void setTrimFieldNames(final boolean trimFieldNames) {
        this.trimFieldNames = trimFieldNames;
    }

    public boolean getTrimFieldNames() {
        return trimFieldNames;
    }

    public void setReceiver(final StreamReceiver receiver) {
        this.receiver = receiver;
    }

    public void reset() {
        getTextAndReset();
        entityName = null;
        literalsEmitted = false;
        subfieldName = null;
    }

    protected void appendText(final char ch) {
        builder.append(ch);
    }

    protected void emitStartEntity() {
        // Output of the startEntity event is postponed
        // until a literal is emitted in order to able
        // to skip empty entities

        entityName = getTextAndReset();
        if (trimFieldNames) {
            entityName = entityName.trim();
        }
        literalsEmitted = false;
    }

    protected void emitEndEntity() {
        if (!literalsEmitted) {
            if (skipEmptyFields || entityName.isEmpty()) {
                return;
            }
            receiver.startEntity(entityName);
            entityName = null;
        }
        receiver.endEntity();
    }

    protected void setSubfieldName(final char name) {
        subfieldName = String.valueOf(name);
    }

    protected void emitLiteral() {
        assert subfieldName != null;
        assert entityName != null || literalsEmitted;

        if (entityName != null) {
            receiver.startEntity(entityName);
            entityName = null;
            literalsEmitted = true;
        }

        String value = getTextAndReset();
        if (normalizeUTF8) {
            value = Normalizer.normalize(value, Form.NFC);
        }
        receiver.literal(subfieldName, value);
        subfieldName = null;
    }

    private String getTextAndReset() {
        final String text = builder.toString();
        builder.setLength(0);
        return text;
    }

}