melnorme.lang.utils.gson.JsonParserX.java Source code

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Here is the source code for melnorme.lang.utils.gson.JsonParserX.java

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/*******************************************************************************
 * Copyright (c) 2016 Bruno Medeiros and other Contributors.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Bruno Medeiros - initial API and implementation
 *******************************************************************************/
package melnorme.lang.utils.gson;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.JsonParser;
import com.google.gson.internal.bind.TypeAdapters;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.MalformedJsonException;

import melnorme.utilbox.core.CommonException;

/**
 * An alternative to {@link JsonParser}, which preservers the statically-checked exception throwing API
 */
public class JsonParserX {

    public static JsonReader newReader(String json, boolean lenient) {
        return newReader(new StringReader(json), lenient);
    }

    public static JsonReader newReader(Reader reader, boolean lenient) {
        JsonReader jsonReader = new JsonReader(reader);
        jsonReader.setLenient(lenient);
        return jsonReader;
    }

    /* -----------------  ----------------- */

    public JsonElement parse(String json, boolean lenient) throws IOException, JsonSyntaxExceptionX {
        return parse(new StringReader(json), lenient);
    }

    public JsonElement parse(Reader reader, boolean lenient) throws IOException, JsonSyntaxExceptionX {
        JsonReader json = new JsonReader(reader);
        boolean originalLenient = json.isLenient();
        json.setLenient(lenient);
        try {
            return parse(json);
        } finally {
            json.setLenient(originalLenient);
        }
    }

    public JsonElement parse(JsonReader reader) throws IOException, JsonSyntaxExceptionX {
        // Based on GSON 2.2.4 code of Streams.parse(json);

        try {
            return TypeAdapters.JSON_ELEMENT.read(reader);
        } catch (MalformedJsonException e) {
            throw new JsonSyntaxExceptionX(e);
        } catch (NumberFormatException e) {
            throw new JsonSyntaxExceptionX(e);
        } catch (JsonParseException e) {
            // I don't think JsonParseException is ever thrown from code above, 
            // not with normal JsonReader at least (a subclass might though). 
            // So just in case, sanitize it:
            throw new JsonSyntaxExceptionX(e.getCause());
        }
    }

    @SuppressWarnings("serial")
    public static class JsonSyntaxExceptionX extends Exception {
        public JsonSyntaxExceptionX(Throwable cause) {
            super(cause);
        }
    }

    /* -----------------  ----------------- */

    public JsonElement parse_common(JsonReader reader) throws CommonException {
        try {
            return parse(reader);
        } catch (IOException e) {
            throw new CommonException("Error reading from input: ", e);
        } catch (JsonSyntaxExceptionX e) {
            throw new CommonException("JSON syntax error: ", e);
        }
    }

    /* -----------------  ----------------- */

    public JsonObject parseObject(JsonReader reader) throws CommonException {
        JsonElement element = parse_common(reader);
        if (element.isJsonObject()) {
            return element.getAsJsonObject();
        } else {
            throw new CommonException("Parsed JSON element is not a JSON object.");
        }
    }

    public JsonObject parseObject(Reader json, boolean lenient) throws CommonException {
        return parseObject(newReader(json, lenient));
    }

    public JsonObject parseObject(String json, boolean lenient) throws CommonException {
        return parseObject(newReader(json, lenient));
    }

}