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JSefa (Java Simple exchange format api) is a simple library for stream-based serialization of java objects to XML, CSV, FLR or any other format and back again using an iterator-style interface independent of the serialization format. The mapping between java object types and types of the serialization format (e. g. xml complex element types) can be defined either by annotating the java classes or programmatically using a simple API. The current implementation supports XML, CSV and FLR - for XML it is based on JSR 173.

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/*
 * Copyright 2007 the original author or authors.
 *
 * 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 net.sf.jsefa.common.converter;

/**
 * Converter for Boolean objects.

 * The format consists of two Strings. The first token is the literal for true and the second the literal for
 * false.

 * 
 * It is thread-safe.
 * 
 * @author Norman Lahme-Huetig
 */
public class BooleanConverter implements SimpleTypeConverter {
    /**
     * Format String with "true" for true and "false" for false.
     */
    protected static final String[] FORMAT_TRUE_FALSE = {"true", "false"};

    /**
     * Format String with "yes" for true and "no" for false.
     */
    protected static final String[] FORMAT_YES_NO = {"yes", "no"};

    /**
     * Format String with "1" for true and "0" for false.
     */
    protected static final String[] FORMAT_BINARY = {"1", "0"};

    private final String trueLiteral;

    private final String falseLiteral;

    /**
     * Creates a new BooleanConverter.

     * If no format is given, the default format (see {@link #getDefaultFormat()}) is used.
     * 
     * @param configuration the configuration.
     * @return a boolean converter
     * @throws ConversionException if the given format is not valid.
     */
    public static BooleanConverter create(SimpleTypeConverterConfiguration configuration) {
        return new BooleanConverter(configuration);
    }

    /**
     * Constructs a new BooleanConverter.

     * If no format is given, the default format (see {@link #getDefaultFormat()}) is used.
     * 
     * @param configuration the configuration.
     * @throws ConversionException if the given format is not valid.
     */
    protected BooleanConverter(SimpleTypeConverterConfiguration configuration) {
        String[] format = getFormat(configuration);
        this.trueLiteral = format[0];
        this.falseLiteral = format[1];
    }

    /**
     * {@inheritDoc}
     */
    public final Boolean fromString(String value) {
        if (value == null || value.length() == 0) {
            return null;
        }
        if (this.trueLiteral.equals(value)) {
            return Boolean.TRUE;
        } else if (this.falseLiteral.equals(value)) {
            return Boolean.FALSE;
        } else {
            throw new ConversionException("Unknown boolean value: " + value);
        }
    }

    /**
     * {@inheritDoc}
     */
    public final String toString(Object value) {
        if (value == null) {
            return null;
        }
        if (((Boolean) value).booleanValue()) {
            return this.trueLiteral;
        } else {
            return this.falseLiteral;
        }
    }

    /**
     * Returns the default format which is used when no format is given.
     * 
     * @return the default format.
     */
    protected String[] getDefaultFormat() {
        return BooleanConverter.FORMAT_TRUE_FALSE;
    }

    private String[] getFormat(SimpleTypeConverterConfiguration configuration) {
        if (configuration.getFormat() == null) {
            return getDefaultFormat();
        }
        if (configuration.getFormat().length != 2) {
            throw new ConversionException("The format for a BooleanConverter must be an array with 2 entries");
        }
        if (configuration.getFormat()[0].equals(configuration.getFormat()[1])) {
            throw new ConversionException("Invalid format for a BooleanConverter: " + configuration.getFormat()[0]
                    + ", " + configuration.getFormat()[1]);
        }
        return configuration.getFormat();
    }

}