com.google.api.client.json.gson.GsonParser.java Source code

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Here is the source code for com.google.api.client.json.gson.GsonParser.java

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/*
 * Copyright (c) 2011 Google Inc.
 *
 * 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.google.api.client.json.gson;

import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.JsonParser;
import com.google.api.client.json.JsonToken;
import com.google.api.client.util.Preconditions;
import com.google.gson.stream.JsonReader;

import java.io.EOFException;
import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;

/**
 * Low-level JSON serializer implementation based on GSON.
 *
 * <p>
 * Implementation is not thread-safe.
 * </p>
 *
 * @author Yaniv Inbar
 */
class GsonParser extends JsonParser {
    private final JsonReader reader;
    private final GsonFactory factory;

    private List<String> currentNameStack = new ArrayList<String>();
    private JsonToken currentToken;
    private String currentText;

    GsonParser(GsonFactory factory, JsonReader reader) {
        this.factory = factory;
        this.reader = reader;
        // lenient to allow top-level values of any type
        reader.setLenient(true);
    }

    @Override
    public void close() throws IOException {
        reader.close();
    }

    @Override
    public String getCurrentName() {
        return currentNameStack.isEmpty() ? null : currentNameStack.get(currentNameStack.size() - 1);
    }

    @Override
    public JsonToken getCurrentToken() {
        return currentToken;
    }

    @Override
    public JsonFactory getFactory() {
        return factory;
    }

    @Override
    public byte getByteValue() {
        checkNumber();
        return Byte.valueOf(currentText);
    }

    @Override
    public short getShortValue() {
        checkNumber();
        return Short.valueOf(currentText);
    }

    @Override
    public int getIntValue() {
        checkNumber();
        return Integer.valueOf(currentText);
    }

    @Override
    public float getFloatValue() {
        checkNumber();
        return Float.valueOf(currentText);
    }

    @Override
    public BigInteger getBigIntegerValue() {
        checkNumber();
        return new BigInteger(currentText);
    }

    @Override
    public BigDecimal getDecimalValue() {
        checkNumber();
        return new BigDecimal(currentText);
    }

    @Override
    public double getDoubleValue() {
        checkNumber();
        return Double.valueOf(currentText);
    }

    @Override
    public long getLongValue() {
        checkNumber();
        return Long.valueOf(currentText);
    }

    private void checkNumber() {
        Preconditions.checkArgument(
                currentToken == JsonToken.VALUE_NUMBER_INT || currentToken == JsonToken.VALUE_NUMBER_FLOAT);
    }

    @Override
    public String getText() {
        return currentText;
    }

    @Override
    public JsonToken nextToken() throws IOException {
        if (currentToken != null) {
            switch (currentToken) {
            case START_ARRAY:
                reader.beginArray();
                currentNameStack.add(null);
                break;
            case START_OBJECT:
                reader.beginObject();
                currentNameStack.add(null);
                break;
            default:
                break;
            }
        }
        // work around bug in GSON parser that it throws an EOFException for an empty document
        // see http://code.google.com/p/google-gson/issues/detail?id=330
        com.google.gson.stream.JsonToken peek;
        try {
            peek = reader.peek();
        } catch (EOFException e) {
            peek = com.google.gson.stream.JsonToken.END_DOCUMENT;
        }
        switch (peek) {
        case BEGIN_ARRAY:
            currentText = "[";
            currentToken = JsonToken.START_ARRAY;
            break;
        case END_ARRAY:
            currentText = "]";
            currentToken = JsonToken.END_ARRAY;
            currentNameStack.remove(currentNameStack.size() - 1);
            reader.endArray();
            break;
        case BEGIN_OBJECT:
            currentText = "{";
            currentToken = JsonToken.START_OBJECT;
            break;
        case END_OBJECT:
            currentText = "}";
            currentToken = JsonToken.END_OBJECT;
            currentNameStack.remove(currentNameStack.size() - 1);
            reader.endObject();
            break;
        case BOOLEAN:
            if (reader.nextBoolean()) {
                currentText = "true";
                currentToken = JsonToken.VALUE_TRUE;
            } else {
                currentText = "false";
                currentToken = JsonToken.VALUE_FALSE;
            }
            break;
        case NULL:
            currentText = "null";
            currentToken = JsonToken.VALUE_NULL;
            reader.nextNull();
            break;
        case STRING:
            currentText = reader.nextString();
            currentToken = JsonToken.VALUE_STRING;
            break;
        case NUMBER:
            currentText = reader.nextString();
            currentToken = currentText.indexOf('.') == -1 ? JsonToken.VALUE_NUMBER_INT
                    : JsonToken.VALUE_NUMBER_FLOAT;
            break;
        case NAME:
            currentText = reader.nextName();
            currentToken = JsonToken.FIELD_NAME;
            currentNameStack.set(currentNameStack.size() - 1, currentText);
            break;
        default:
            currentText = null;
            currentToken = null;
        }
        return currentToken;
    }

    @Override
    public JsonParser skipChildren() throws IOException {
        if (currentToken != null) {
            switch (currentToken) {
            case START_ARRAY:
                reader.skipValue();
                currentText = "]";
                currentToken = JsonToken.END_ARRAY;
                break;
            case START_OBJECT:
                reader.skipValue();
                currentText = "}";
                currentToken = JsonToken.END_OBJECT;
                break;
            default:
                break;
            }
        }
        return this;
    }
}