JSON.java

/*
 * Copyright © 2011 Jason J.A. Stephenson
 * 
 * This file is part of sigio.jar.
 * 
 * sigio.jar is free software: you can redistribute it and/or modify it
 * under the terms of the Lesser GNU General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * sigio.jar is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * Lesser GNU General Public License for more details.
 * 
 * You should have received a copy of the Lesser GNU General Public License
 * along with sigio.jar.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.sigio.json;

/**
 * JSON character constants and character utility routines based on
 * RFC4627.
 */
public class JSON {
  /**
   * Character that opens a JSON array sequence.
   */
  public static final int BEGIN_ARRAY = '[';
  /**
   * Character that closes a JSON array sequence.
   */
  public static final int END_ARRAY = ']';
  /**
   * Character that opens a JSON object sequence.
   */
  public static final int BEGIN_OBJECT = '{';
  /**
   * Character that closes a JSON object sequence.
   */
  public static final int END_OBJECT = '}';
  /**
   * Character that opens and closes JSON strings.
   */
  public static final int QUOTE_CHAR = '"';
  /**
   * Character that separates an object field name from the value.
   */
  public static final int NAME_SEPARATOR = ':';
  /**
   * Character that separates fields in an array or object.
   */
  public static final int VALUE_SEPARATOR = ',';
  /**
   * Array of whitespace characters in a JSON format.
   */
  public static final int[] WHITESPACE = { ' ', '\t', '\r', '\n' };
  /**
   * Character that escapes special characters.
   */
  public static final int ESCAPE_CHAR = '\\';

  /**
   * Check if a character is whitespace according to the standard.
   *
   * @param c int value of character to check.
   * @return <code>true</code> if the character is whitespace,
   * <code>false</code> if not
   */
  public static boolean isWhiteSpace(int c) {
    for (int x : JSON.WHITESPACE) {
      if (c == x)
        return true;
    }
    return false;
  }

  /**
   * Check if a string represents a number according to RFC4627.
   *
   * @param str the string to check
   * @return <code>true</code> if the string matches the JSON
   * specification for a number, <code>false</code> if not
   */
  public static boolean isNumber(String str) {
    return str.matches("-?[0-9]+(?:\\.[0-9]+)?(?:[eE][-+]?[0-9]+)?");
  }

  // Private constructor, so we don't see it in javadoc and so we
  // don't accidentally try to instantiate one.
  private JSON() { super(); }

}