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   1  <?php
   2  
   3  /*
   4   * This file is part of the Symfony package.
   5   *
   6   * (c) Fabien Potencier <fabien@symfony.com>
   7   *
   8   * For the full copyright and license information, please view the LICENSE
   9   * file that was distributed with this source code.
  10   */
  11  
  12  namespace Symfony\Component\Yaml;
  13  
  14  /**
  15   * Escaper encapsulates escaping rules for single and double-quoted
  16   * YAML strings.
  17   *
  18   * @author Matthew Lewinski <matthew@lewinski.org>
  19   */
  20  class Escaper
  21  {
  22      // Characters that would cause a dumped string to require double quoting.
  23      const REGEX_CHARACTER_TO_ESCAPE = "[\\x00-\\x1f]|\xc2\x85|\xc2\xa0|\xe2\x80\xa8|\xe2\x80\xa9";
  24  
  25      // Mapping arrays for escaping a double quoted string. The backslash is
  26      // first to ensure proper escaping because str_replace operates iteratively
  27      // on the input arrays. This ordering of the characters avoids the use of strtr,
  28      // which performs more slowly.
  29      private static $escapees = array('\\', '\\\\', '\\"', '"',
  30                                       "\x00",  "\x01",  "\x02",  "\x03",  "\x04",  "\x05",  "\x06",  "\x07",
  31                                       "\x08",  "\x09",  "\x0a",  "\x0b",  "\x0c",  "\x0d",  "\x0e",  "\x0f",
  32                                       "\x10",  "\x11",  "\x12",  "\x13",  "\x14",  "\x15",  "\x16",  "\x17",
  33                                       "\x18",  "\x19",  "\x1a",  "\x1b",  "\x1c",  "\x1d",  "\x1e",  "\x1f",
  34                                       "\xc2\x85", "\xc2\xa0", "\xe2\x80\xa8", "\xe2\x80\xa9");
  35      private static $escaped = array('\\\\', '\\"', '\\\\', '\\"',
  36                                       '\\0',   '\\x01', '\\x02', '\\x03', '\\x04', '\\x05', '\\x06', '\\a',
  37                                       '\\b',   '\\t',   '\\n',   '\\v',   '\\f',   '\\r',   '\\x0e', '\\x0f',
  38                                       '\\x10', '\\x11', '\\x12', '\\x13', '\\x14', '\\x15', '\\x16', '\\x17',
  39                                       '\\x18', '\\x19', '\\x1a', '\\e',   '\\x1c', '\\x1d', '\\x1e', '\\x1f',
  40                                       '\\N', '\\_', '\\L', '\\P');
  41  
  42      /**
  43       * Determines if a PHP value would require double quoting in YAML.
  44       *
  45       * @param string $value A PHP value
  46       *
  47       * @return bool True if the value would require double quotes.
  48       */
  49      public static function requiresDoubleQuoting($value)
  50      {
  51          return preg_match('/'.self::REGEX_CHARACTER_TO_ESCAPE.'/u', $value);
  52      }
  53  
  54      /**
  55       * Escapes and surrounds a PHP value with double quotes.
  56       *
  57       * @param string $value A PHP value
  58       *
  59       * @return string The quoted, escaped string
  60       */
  61      public static function escapeWithDoubleQuotes($value)
  62      {
  63          return sprintf('"%s"', str_replace(self::$escapees, self::$escaped, $value));
  64      }
  65  
  66      /**
  67       * Determines if a PHP value would require single quoting in YAML.
  68       *
  69       * @param string $value A PHP value
  70       *
  71       * @return bool True if the value would require single quotes.
  72       */
  73      public static function requiresSingleQuoting($value)
  74      {
  75          // Determines if a PHP value is entirely composed of a value that would
  76          // require single quoting in YAML.
  77          if (in_array(strtolower($value), array('null', '~', 'true', 'false', 'y', 'n', 'yes', 'no', 'on', 'off'))) {
  78              return true;
  79          }
  80  
  81          // Determines if the PHP value contains any single characters that would
  82          // cause it to require single quoting in YAML.
  83          return preg_match('/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ \- ? | < > = ! % @ ` ]/x', $value);
  84      }
  85  
  86      /**
  87       * Escapes and surrounds a PHP value with single quotes.
  88       *
  89       * @param string $value A PHP value
  90       *
  91       * @return string The quoted, escaped string
  92       */
  93      public static function escapeWithSingleQuotes($value)
  94      {
  95          return sprintf("'%s'", str_replace('\'', '\'\'', $value));
  96      }
  97  }