json.php

<?php
/**
 * dropFW(tm) :  PHP Web Development Framework (http://www.suncoding.com)
 * Copyright 2010, Sun Web Dev, Inc.
 *
 * Licensed under The GPLv3 License
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright	Copyright 2010, Sun Web Dev, Inc. (http://www.suncoding.com)
 * @version	1.0.0
 * @author	Pavan Kumar Sunkara
 * @license	GPLv3
 */

/**
 * Marker constant for Json::decode(), used to flag stack state
 */
define('JSON_SLICE',   1);

/**
 * Marker constant for Json::decode(), used to flag stack state
 */
define('JSON_IN_STR',  2);

/**
 * Marker constant for Json::decode(), used to flag stack state
 */
define('JSON_IN_ARR',  3);

/**
 * Marker constant for Json::decode(), used to flag stack state
 */
define('JSON_IN_OBJ',  4);

/**
 * Marker constant for Json::decode(), used to flag stack state
 */
define('JSON_IN_CMT', 5);

/**
 * Behavior switch for Json::decode()
 */
define('JSON_LOOSE_TYPE', 16);

/**
 * Behavior switch for Json::decode()
 */
define('JSON_SUPPRESS_ERRORS', 0);

/**
 * Converts to and from JSON format.
 *
 * Brief example of use:
 *
 * <code>
 * // create a new instance of JSON
 * $json = new JSON();
 *
 * // convert a complexe value to JSON notation, and send it to the browser
 * $value = array('foo', 'bar', array(1, 2, 'baz'), array(3, array(4)));
 * $output = $json->encode($value);
 *
 * print($output);
 * // prints: ["foo","bar",[1,2,"baz"],[3,[4]]]
 *
 * // accept incoming POST data, assumed to be in JSON notation
 * $input = file_get_contents('php://input', 1000000);
 * $value = $json->decode($input);
 * </code>
 */
class Json extends Object {
/**
 * constructs a new JSON instance
 *
 * @param int $use object behavior flags; combine with boolean-OR
 *
 *	   possible values:
 *	   - JSON_LOOSE_TYPE:  loose typing.
 *		   "{...}" syntax creates associative arrays
 *		   instead of objects in decode().
 *	   - JSON_SUPPRESS_ERRORS:  error suppression.
 *		   Values which can't be encoded (e.g. resources)
 *		   appear as NULL instead of throwing errors.
 *		   By default, a deeply-nested resource will
 *		   bubble up with an error, so all return values
 *		   from encode() should be checked with isError()
 */
	function __construct($use = 0) {
		$this->use = $use;
	}

/**
 * convert a string from one UTF-16 char to one UTF-8 char
 *
 * Normally should be handled by mb_convert_encoding, but
 * provides a slower PHP-only method for installations
 * that lack the multibye string extension.
 *
 * @param    string  $utf16  UTF-16 character
 * @return   string  UTF-8 character
 * @access   private
 */
	function utf162utf8($utf16) {
		// oh please oh please oh please oh please oh please
		if(function_exists('mb_convert_encoding')) {
			return mb_convert_encoding($utf16, 'UTF-8', 'UTF-16');
		}

		$bytes = (ord($utf16{0}) << 8) | ord($utf16{1});

		switch(true) {
			case ((0x7F & $bytes) == $bytes):
				// this case should never be reached, because we are in ASCII range
				// see: http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
				return chr(0x7F & $bytes);

			case (0x07FF & $bytes) == $bytes:
				// return a 2-byte UTF-8 character
				// see: http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
				return chr(0xC0 | (($bytes >> 6) & 0x1F))
					 . chr(0x80 | ($bytes & 0x3F));

			case (0xFFFF & $bytes) == $bytes:
				// return a 3-byte UTF-8 character
				// see: http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
				return chr(0xE0 | (($bytes >> 12) & 0x0F))
					 . chr(0x80 | (($bytes >> 6) & 0x3F))
					 . chr(0x80 | ($bytes & 0x3F));
		}

		// ignoring UTF-32 for now, sorry
		return '';
	}

/**
 * convert a string from one UTF-8 char to one UTF-16 char
 *
 * Normally should be handled by mb_convert_encoding, but
 * provides a slower PHP-only method for installations
 * that lack the multibye string extension.
 *
 * @param    string  $utf8   UTF-8 character
 * @return   string  UTF-16 character
 * @access   private
 */
	function utf82utf16($utf8) {
		// oh please oh please oh please oh please oh please
		if(function_exists('mb_convert_encoding')) {
			return mb_convert_encoding($utf8, 'UTF-16', 'UTF-8');
		}

		switch(strlen($utf8)) {
			case 1:
				// this case should never be reached, because we are in ASCII range
				// see: http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
				return $utf8;

			case 2:
				// return a UTF-16 character from a 2-byte UTF-8 char
				// see: http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
				return chr(0x07 & (ord($utf8{0}) >> 2))
					 . chr((0xC0 & (ord($utf8{0}) << 6))
						 | (0x3F & ord($utf8{1})));

			case 3:
				// return a UTF-16 character from a 3-byte UTF-8 char
				// see: http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
				return chr((0xF0 & (ord($utf8{0}) << 4))
						 | (0x0F & (ord($utf8{1}) >> 2)))
					 . chr((0xC0 & (ord($utf8{1}) << 6))
						 | (0x7F & ord($utf8{2})));
		}

		// ignoring UTF-32 for now, sorry
		return '';
	}

/**
 * encodes an arbitrary variable into JSON format
 *
 * @param    mixed   $var any number, boolean, string, array, or object to be encoded.
 *		   see argument 1 to JSON() above for array-parsing behavior.
 *		   if var is a strng, note that encode() always expects it
 *		   to be in ASCII or UTF-8 format!
 *
 * @return   mixed   JSON string representation of input var or an error if a problem occurs
 * @access   public
 */
	function encode($var) {
		switch (gettype($var)) {
			case 'boolean':
				return $var ? 'true' : 'false';

			case 'NULL':
				return 'null';

			case 'integer':
				return (int) $var;

			case 'double':
			case 'float':
				return (float) $var;

			case 'string':
				// STRINGS ARE EXPECTED TO BE IN ASCII OR UTF-8 FORMAT
				$ascii = '';
				$strlen_var = strlen($var);

			   /*
				* Iterate over every character in the string,
				* escaping with a slash or encoding to UTF-8 where necessary
				*/
				for ($c = 0; $c < $strlen_var; ++$c) {

					$ord_var_c = ord($var{$c});

					switch (true) {
						case $ord_var_c == 0x08:
							$ascii .= '\b';
							break;
						case $ord_var_c == 0x09:
							$ascii .= '\t';
							break;
						case $ord_var_c == 0x0A:
							$ascii .= '\n';
							break;
						case $ord_var_c == 0x0C:
							$ascii .= '\f';
							break;
						case $ord_var_c == 0x0D:
							$ascii .= '\r';
							break;

						case $ord_var_c == 0x22:
						case $ord_var_c == 0x2F:
						case $ord_var_c == 0x5C:
							// double quote, slash, slosh
							$ascii .= '\\'.$var{$c};
							break;

						case (($ord_var_c >= 0x20) && ($ord_var_c <= 0x7F)):
							// characters U-00000000 - U-0000007F (same as ASCII)
							$ascii .= $var{$c};
							break;

						case (($ord_var_c & 0xE0) == 0xC0):
							// characters U-00000080 - U-000007FF, mask 110XXXXX
							// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
							$char = pack('C*', $ord_var_c, ord($var{$c + 1}));
							$c += 1;
							$utf16 = $this->utf82utf16($char);
							$ascii .= sprintf('\u%04s', bin2hex($utf16));
							break;

						case (($ord_var_c & 0xF0) == 0xE0):
							// characters U-00000800 - U-0000FFFF, mask 1110XXXX
							// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
							$char = pack('C*', $ord_var_c,
										 ord($var{$c + 1}),
										 ord($var{$c + 2}));
							$c += 2;
							$utf16 = $this->utf82utf16($char);
							$ascii .= sprintf('\u%04s', bin2hex($utf16));
							break;

						case (($ord_var_c & 0xF8) == 0xF0):
							// characters U-00010000 - U-001FFFFF, mask 11110XXX
							// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
							$char = pack('C*', $ord_var_c,
										 ord($var{$c + 1}),
										 ord($var{$c + 2}),
										 ord($var{$c + 3}));
							$c += 3;
							$utf16 = $this->utf82utf16($char);
							$ascii .= sprintf('\u%04s', bin2hex($utf16));
							break;

						case (($ord_var_c & 0xFC) == 0xF8):
							// characters U-00200000 - U-03FFFFFF, mask 111110XX
							// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
							$char = pack('C*', $ord_var_c,
										 ord($var{$c + 1}),
										 ord($var{$c + 2}),
										 ord($var{$c + 3}),
										 ord($var{$c + 4}));
							$c += 4;
							$utf16 = $this->utf82utf16($char);
							$ascii .= sprintf('\u%04s', bin2hex($utf16));
							break;

						case (($ord_var_c & 0xFE) == 0xFC):
							// characters U-04000000 - U-7FFFFFFF, mask 1111110X
							// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
							$char = pack('C*', $ord_var_c,
										 ord($var{$c + 1}),
										 ord($var{$c + 2}),
										 ord($var{$c + 3}),
										 ord($var{$c + 4}),
										 ord($var{$c + 5}));
							$c += 5;
							$utf16 = $this->utf82utf16($char);
							$ascii .= sprintf('\u%04s', bin2hex($utf16));
							break;
					}
				}

				return '"'.$ascii.'"';

			case 'array':
			   /*
				* As per JSON spec if any array key is not an integer
				* we must treat the the whole array as an object. We
				* also try to catch a sparsely populated associative
				* array with numeric keys here because some JS engines
				* will create an array with empty indexes up to
				* max_index which can cause memory issues and because
				* the keys, which may be relevant, will be remapped
				* otherwise.
				*
				* As per the ECMA and JSON specification an object may
				* have any string as a property. Unfortunately due to
				* a hole in the ECMA specification if the key is a
				* ECMA reserved word or starts with a digit the
				* parameter is only accessible using ECMAScript's
				* bracket notation.
				*/

				// treat as a JSON object
				if (is_array($var) && count($var) && (array_keys($var) !== range(0, sizeof($var) - 1))) {
					$properties = array_map(array($this, 'name_value'),
											array_keys($var),
											array_values($var));

					return '{' . join(',', $properties) . '}';
				}

				// treat it like a regular array
				$elements = array_map(array($this, 'encode'), $var);

				return '[' . join(',', $elements) . ']';

			case 'object':
				$vars = get_object_vars($var);

				$properties = array_map(array($this, 'name_value'),
										array_keys($vars),
										array_values($vars));

				return '{' . join(',', $properties) . '}';

			default:
				if($this->use & JSON_SUPPRESS_ERRORS)
					return 'null';
				else
					$this->error($var);
		}
	}

/**
 * array-walking function for use in generating JSON-formatted name-value pairs
 *
 * @param string  $name   name of key to use
 * @param mixed   $value  reference to an array element to be encoded
 *
 * @return   string  JSON-formatted name-value pair, like '"name":value'
 * @access   private
 */
	function name_value($name, $value) {
		$encoded_value = $this->encode($value);

		return $this->encode(strval($name)) . ':' . $encoded_value;
	}

/**
 * reduce a string by removing leading and trailing comments and whitespace
 *
 * @param    $str    string string value to strip of comments and whitespace
 *
 * @return   string  string value stripped of comments and whitespace
 * @access   private
 */
	function reduce_string($str) {
		$str = preg_replace(array(

				// eliminate single line comments in '// ...' form
				'#^\s*//(.+)$#m',

				// eliminate multi-line comments in '/* ... */' form, at start of string
				'#^\s*/\*(.+)\*/#Us',

				// eliminate multi-line comments in '/* ... */' form, at end of string
				'#/\*(.+)\*/\s*$#Us'

			), '', $str);

		// eliminate extraneous space
		return trim($str);
	}

/**
 * decodes a JSON string into appropriate variable
 *
 * @param    string  $str JSON-formatted string
 *
 * @return   mixed   number, boolean, string, array, or object
 *				   corresponding to given JSON input string.
 *				   See argument 1 to JSON() above for object-output behavior.
 *				   Note that decode() always returns strings
 *				   in ASCII or UTF-8 format!
 * @access   public
 */
	function decode($str) {
		$str = $this->reduce_string($str);

		switch (strtolower($str)) {
			case 'true':
				return true;

			case 'false':
				return false;

			case 'null':
				return null;

			default:
				$m = array();

				if (is_numeric($str)) {
					// Lookie-loo, it's a number

					// This would work on its own, but I'm trying to be
					// good about returning integers where appropriate:
					// return (float)$str;

					// Return float or int, as appropriate
					return ((float)$str == (integer)$str)
						? (integer)$str
						: (float)$str;

				} elseif (preg_match('/^("|\').*(\1)$/s', $str, $m) && $m[1] == $m[2]) {
					// STRINGS RETURNED IN UTF-8 FORMAT
					$delim = substr($str, 0, 1);
					$chrs = substr($str, 1, -1);
					$utf8 = '';
					$strlen_chrs = strlen($chrs);

					for ($c = 0; $c < $strlen_chrs; ++$c) {

						$substr_chrs_c_2 = substr($chrs, $c, 2);
						$ord_chrs_c = ord($chrs{$c});

						switch (true) {
							case $substr_chrs_c_2 == '\b':
								$utf8 .= chr(0x08);
								++$c;
								break;
							case $substr_chrs_c_2 == '\t':
								$utf8 .= chr(0x09);
								++$c;
								break;
							case $substr_chrs_c_2 == '\n':
								$utf8 .= chr(0x0A);
								++$c;
								break;
							case $substr_chrs_c_2 == '\f':
								$utf8 .= chr(0x0C);
								++$c;
								break;
							case $substr_chrs_c_2 == '\r':
								$utf8 .= chr(0x0D);
								++$c;
								break;

							case $substr_chrs_c_2 == '\\"':
							case $substr_chrs_c_2 == '\\\'':
							case $substr_chrs_c_2 == '\\\\':
							case $substr_chrs_c_2 == '\\/':
								if (($delim == '"' && $substr_chrs_c_2 != '\\\'') ||
								   ($delim == "'" && $substr_chrs_c_2 != '\\"')) {
									$utf8 .= $chrs{++$c};
								}
								break;

							case preg_match('/\\\u[0-9A-F]{4}/i', substr($chrs, $c, 6)):
								// single, escaped unicode character
								$utf16 = chr(hexdec(substr($chrs, ($c + 2), 2)))
									   . chr(hexdec(substr($chrs, ($c + 4), 2)));
								$utf8 .= $this->utf162utf8($utf16);
								$c += 5;
								break;

							case ($ord_chrs_c >= 0x20) && ($ord_chrs_c <= 0x7F):
								$utf8 .= $chrs{$c};
								break;

							case ($ord_chrs_c & 0xE0) == 0xC0:
								// characters U-00000080 - U-000007FF, mask 110XXXXX
								//see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
								$utf8 .= substr($chrs, $c, 2);
								++$c;
								break;

							case ($ord_chrs_c & 0xF0) == 0xE0:
								// characters U-00000800 - U-0000FFFF, mask 1110XXXX
								// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
								$utf8 .= substr($chrs, $c, 3);
								$c += 2;
								break;

							case ($ord_chrs_c & 0xF8) == 0xF0:
								// characters U-00010000 - U-001FFFFF, mask 11110XXX
								// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
								$utf8 .= substr($chrs, $c, 4);
								$c += 3;
								break;

							case ($ord_chrs_c & 0xFC) == 0xF8:
								// characters U-00200000 - U-03FFFFFF, mask 111110XX
								// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
								$utf8 .= substr($chrs, $c, 5);
								$c += 4;
								break;

							case ($ord_chrs_c & 0xFE) == 0xFC:
								// characters U-04000000 - U-7FFFFFFF, mask 1111110X
								// see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
								$utf8 .= substr($chrs, $c, 6);
								$c += 5;
								break;

						}

					}

					return $utf8;

				} elseif (preg_match('/^\[.*\]$/s', $str) || preg_match('/^\{.*\}$/s', $str)) {
					// array, or object notation

					if ($str{0} == '[') {
						$stk = array(JSON_IN_ARR);
						$arr = array();
					} else {
						if ($this->use & JSON_LOOSE_TYPE) {
							$stk = array(JSON_IN_OBJ);
							$obj = array();
						} else {
							$stk = array(JSON_IN_OBJ);
							$obj = new stdClass();
						}
					}

					array_push($stk, array('what'  => JSON_SLICE,
										   'where' => 0,
										   'delim' => false));

					$chrs = substr($str, 1, -1);
					$chrs = $this->reduce_string($chrs);

					if ($chrs == '') {
						if (reset($stk) == JSON_IN_ARR) {
							return $arr;

						} else {
							return $obj;

						}
					}

					//print("\nparsing {$chrs}\n");

					$strlen_chrs = strlen($chrs);

					for ($c = 0; $c <= $strlen_chrs; ++$c) {

						$top = end($stk);
						$substr_chrs_c_2 = substr($chrs, $c, 2);

						if (($c == $strlen_chrs) || (($chrs{$c} == ',') && ($top['what'] == JSON_SLICE))) {
							// found a comma that is not inside a string, array, etc.,
							// OR we've reached the end of the character list
							$slice = substr($chrs, $top['where'], ($c - $top['where']));
							array_push($stk, array('what' => JSON_SLICE, 'where' => ($c + 1), 'delim' => false));
							//print("Found split at {$c}: ".substr($chrs, $top['where'], (1 + $c - $top['where']))."\n");

							if (reset($stk) == JSON_IN_ARR) {
								// we are in an array, so just push an element onto the stack
								array_push($arr, $this->decode($slice));

							} elseif (reset($stk) == JSON_IN_OBJ) {
								// we are in an object, so figure
								// out the property name and set an
								// element in an associative array,
								// for now
								$parts = array();
								
								if (preg_match('/^\s*(["\'].*[^\\\]["\'])\s*:\s*(\S.*),?$/Uis', $slice, $parts)) {
									// "name":value pair
									$key = $this->decode($parts[1]);
									$val = $this->decode($parts[2]);

									if ($this->use & JSON_LOOSE_TYPE) {
										$obj[$key] = $val;
									} else {
										$obj->$key = $val;
									}
								} elseif (preg_match('/^\s*(\w+)\s*:\s*(\S.*),?$/Uis', $slice, $parts)) {
									// name:value pair, where name is unquoted
									$key = $parts[1];
									$val = $this->decode($parts[2]);

									if ($this->use & JSON_LOOSE_TYPE) {
										$obj[$key] = $val;
									} else {
										$obj->$key = $val;
									}
								}

							}

						} elseif ((($chrs{$c} == '"') || ($chrs{$c} == "'")) && ($top['what'] != JSON_IN_STR)) {
							// found a quote, and we are not inside a string
							array_push($stk, array('what' => JSON_IN_STR, 'where' => $c, 'delim' => $chrs{$c}));
							//print("Found start of string at {$c}\n");

						} elseif (($chrs{$c} == $top['delim']) &&
								 ($top['what'] == JSON_IN_STR) &&
								 ((strlen(substr($chrs, 0, $c)) - strlen(rtrim(substr($chrs, 0, $c), '\\'))) % 2 != 1)) {
							// found a quote, we're in a string, and it's not escaped
							// we know that it's not escaped becase there is _not_ an
							// odd number of backslashes at the end of the string so far
							array_pop($stk);
							//print("Found end of string at {$c}: ".substr($chrs, $top['where'], (1 + 1 + $c - $top['where']))."\n");

						} elseif (($chrs{$c} == '[') &&
								 in_array($top['what'], array(JSON_SLICE, JSON_IN_ARR, JSON_IN_OBJ))) {
							// found a left-bracket, and we are in an array, object, or slice
							array_push($stk, array('what' => JSON_IN_ARR, 'where' => $c, 'delim' => false));
							//print("Found start of array at {$c}\n");

						} elseif (($chrs{$c} == ']') && ($top['what'] == JSON_IN_ARR)) {
							// found a right-bracket, and we're in an array
							array_pop($stk);
							//print("Found end of array at {$c}: ".substr($chrs, $top['where'], (1 + $c - $top['where']))."\n");

						} elseif (($chrs{$c} == '{') &&
								 in_array($top['what'], array(JSON_SLICE, JSON_IN_ARR, JSON_IN_OBJ))) {
							// found a left-brace, and we are in an array, object, or slice
							array_push($stk, array('what' => JSON_IN_OBJ, 'where' => $c, 'delim' => false));
							//print("Found start of object at {$c}\n");

						} elseif (($chrs{$c} == '}') && ($top['what'] == JSON_IN_OBJ)) {
							// found a right-brace, and we're in an object
							array_pop($stk);
							//print("Found end of object at {$c}: ".substr($chrs, $top['where'], (1 + $c - $top['where']))."\n");

						} elseif (($substr_chrs_c_2 == '/*') &&
								 in_array($top['what'], array(JSON_SLICE, JSON_IN_ARR, JSON_IN_OBJ))) {
							// found a comment start, and we are in an array, object, or slice
							array_push($stk, array('what' => JSON_IN_CMT, 'where' => $c, 'delim' => false));
							$c++;
							//print("Found start of comment at {$c}\n");

						} elseif (($substr_chrs_c_2 == '*/') && ($top['what'] == JSON_IN_CMT)) {
							// found a comment end, and we're in one now
							array_pop($stk);
							$c++;

							for ($i = $top['where']; $i <= $c; ++$i)
								$chrs = substr_replace($chrs, ' ', $i, 1);

							//print("Found end of comment at {$c}: ".substr($chrs, $top['where'], (1 + $c - $top['where']))."\n");

						}

					}

					if (reset($stk) == JSON_IN_ARR) {
						return $arr;

					} elseif (reset($stk) == JSON_IN_OBJ) {
						return $obj;

					}

				}
		}
	}

	function error($data) {
		Error::json($data);
	}
}

?>