com.talvish.tales.serialization.json.translators.StringToJsonElementToChainTranslator.java Source code

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Here is the source code for com.talvish.tales.serialization.json.translators.StringToJsonElementToChainTranslator.java

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// ***************************************************************************
// *  Copyright 2012 Joseph Molnar
// *
// *  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 com.talvish.tales.serialization.json.translators;

import com.google.gson.JsonNull;
import com.google.gson.JsonParseException;
import com.google.gson.JsonParser;
import com.talvish.tales.parts.translators.TranslationException;
import com.talvish.tales.parts.translators.Translator;

/**
 * A translator that parses a string into {@code JsonElements}s before passing to 
 * another translator.
 * @author jmolnar
 *
 */
public class StringToJsonElementToChainTranslator implements Translator {
    // TODO: consider inheriting from one of the string translators
    private static final JsonParser parser = new JsonParser(); // this is thread safe, so we only need one
    private final Translator chainedTranslator;

    public StringToJsonElementToChainTranslator(Translator theChainedTranslator) {
        chainedTranslator = theChainedTranslator;
    }

    @Override
    public Object translate(Object anObject) {
        Object returnValue;
        if (anObject == null) {
            returnValue = chainedTranslator.translate(JsonNull.INSTANCE);
        } else {
            try {
                // NOTE: there is a bug in GSON that if the string is missing an ending curly brace then it doesn't report a json parsing exception
                returnValue = chainedTranslator.translate(parser.parse((String) anObject));
            } catch (JsonParseException e) {
                throw new TranslationException(e);
            } catch (ClassCastException e) {
                throw new TranslationException(e);
            }
        }
        return returnValue;
    }
}