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The public API classes of the Apache MyFaces CORE JSF-2.1 project
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/*
 * 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 jakarta.faces.convert;

import jakarta.faces.component.UIComponent;
import jakarta.faces.context.FacesContext;

import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFConverter;

import java.text.DecimalFormatSymbols;
import java.util.Locale;
import org.apache.myfaces.core.api.shared.MessageUtils;
import org.apache.myfaces.core.api.shared.lang.Assert;

/**
 * see Javadoc of Faces Specification
 */
@JSFConverter
public class DoubleConverter implements Converter
{
    public static final String CONVERTER_ID = "jakarta.faces.Double";
    public static final String STRING_ID = "jakarta.faces.converter.STRING";
    public static final String DOUBLE_ID = "jakarta.faces.converter.DoubleConverter.DOUBLE";

    public DoubleConverter()
    {
    }

    @Override
    public Object getAsObject(FacesContext facesContext, UIComponent uiComponent, String value)
    {
        Assert.notNull(facesContext, "facesContext");
        Assert.notNull(uiComponent, "uiComponent");

        if (value == null)
        {
            return null;
        }
        
        value = value.trim();
        if (value.length() < 1)
        {
            return null;
        }
        
        try
        {
            value = fixLocale(facesContext, value);
            return Double.valueOf(value);
        }
        catch (NumberFormatException e)
        {
            throw new ConverterException(MessageUtils.getErrorMessage(facesContext,
                           DOUBLE_ID,
                           new Object[]{value,"4214",MessageUtils.getLabel(facesContext, uiComponent)}), e);
        }
    }

    /**
     * Since Double.valueOf is not Locale aware, and NumberFormatter
     * cannot parse E values correctly, we need to make a US Locale
     * string from our input value.
     * E.g. '34,383e3' will be translated to '34.383e3' if Locale.DE
     * is set in the {@link jakarta.faces.component.UIViewRoot#getLocale()}
     *
     * @param facesContext
     * @param value
     * @return the 'fixed' value String
     */
    private String fixLocale(FacesContext facesContext, String value)
    {
        Locale loc = facesContext.getViewRoot().getLocale();
        if (loc == null || loc == Locale.US)
        {
            // nothing to fix if we are already using the US Locale
            return value;
        }


        DecimalFormatSymbols dfs = DecimalFormatSymbols.getInstance(loc);
        char decSep = dfs.getDecimalSeparator();

        // replace decimal separators which are different to '.'
        if (decSep != '.' && value.lastIndexOf(decSep) >= 0)
        {
            StringBuilder sbVal = new StringBuilder();

            // remove all groupSeperators and change the decimalSeperator
            for (int i = 0; i < value.length(); i++)
            {
                if (value.charAt(i) == decSep)
                {
                    sbVal.append('.'); // we append the Locale.US decimal separator
                    continue;
                }

                // just append all other characters as usual
                sbVal.append(value.charAt(i));
            }

            value = sbVal.toString();
        }

        // we need the formatter with the correct Locale of the user
        return value;
    }

    @Override
    public String getAsString(FacesContext facesContext, UIComponent uiComponent, Object value)
    {
        Assert.notNull(facesContext, "facesContext");
        Assert.notNull(uiComponent, "uiComponent");

        if (value == null)
        {
            return "";
        }

        if (value instanceof String)
        {
            return (String) value;
        }

        try
        {
            return Double.toString(((Number)value).doubleValue());
        }
        catch (Exception e)
        {
            throw new ConverterException(MessageUtils.getErrorMessage(facesContext, STRING_ID,
                    new Object[]{value,MessageUtils.getLabel(facesContext, uiComponent)}),e);
        }
    }

}