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/**
 * Copyright 2011 The PlayN 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 playn.core.json;

import java.math.BigInteger;

/**
 * Simple JSON parser.
 * 
 *  * Object json = {@link JsonParser}.any().from("{\"a\":[true,false], \"b\":1}");
 * Number json = ({@link Number}){@link JsonParser}.any().from("123.456e7");
 * JsonObject json = {@link JsonParser}.object().from("{\"a\":[true,false], \"b\":1}");
 * JsonArray json = {@link JsonParser}.array().from("[1, {\"a\":[true,false], \"b\":1}]");
 * 
 */
final class JsonParser {
  private int linePos = 1, rowPos, charOffset, utf8adjust;
  private int tokenLinePos, tokenCharPos, tokenCharOffset;
  private Object value;
  private Token token;
  private StringBuilder reusableBuffer = new StringBuilder();

  private boolean eof;
  private int index;
  private String string;
  private int bufferLength;

  private static final char[] TRUE = { 'r', 'u', 'e' };
  private static final char[] FALSE = { 'a', 'l', 's', 'e' };
  private static final char[] NULL = { 'u', 'l', 'l' };

  /**
   * The tokens available in JSON.
   */
  private enum Token {
    EOF(false), NULL(true), TRUE(true), FALSE(true), STRING(true), NUMBER(true), COMMA(false), COLON(false), //
    OBJECT_START(true), OBJECT_END(false), ARRAY_START(true), ARRAY_END(false);
    public boolean isValue;

    Token(boolean isValue) {
      this.isValue = isValue;
    }
  }

  /**
   * Returns a type-safe parser context for a {@link JsonObject}, {@link JsonArray} or "any" type from which you can
   * parse a {@link String}.
   */
  public static final class JsonParserContext {
    private final Class clazz;

    JsonParserContext(Class clazz) {
      this.clazz = clazz;
    }

    /**
     * Parses the current JSON type from a {@link String}.
     */
    public T from(String s) throws JsonParserException {
      return new JsonParser(s).parse(clazz);
    }
  }

  JsonParser(String s) throws JsonParserException {
    this.string = s;
    this.bufferLength = s.length();
    eof = s.isEmpty();
  }

  /**
   * Parses a {@link JsonObject} from a source.
   * 
   *    * JsonObject json = {@link JsonParser}.object().from("{\"a\":[true,false], \"b\":1}");
   * 
   */
  public static JsonParserContext object() {
    return new JsonParserContext(JsonObject.class);
  }

  /**
   * Parses a {@link JsonArray} from a source.
   * 
   *    * JsonArray json = {@link JsonParser}.array().from("[1, {\"a\":[true,false], \"b\":1}]");
   * 
   */
  public static JsonParserContext array() {
    return new JsonParserContext(JsonArray.class);
  }

  /**
   * Parses any object from a source. For any valid JSON, returns either a null (for the JSON string 'null'), a
   * {@link String}, a {@link Number}, a {@link Boolean}, a {@link JsonObject} or a {@link JsonArray}.
   * 
   *    * Object json = {@link JsonParser}.any().from("{\"a\":[true,false], \"b\":1}");
   * Number json = ({@link Number}){@link JsonParser}.any().from("123.456e7");
   * 
   */
  public static JsonParserContext