original_string: protected function setConditionalCommentsPlaceholder($contents, PlaceholderContainer $placeholderContainer)
      {
          return preg_replace_callback(
              '/
                  (
                      <!                  # Match the start of a comment
                      (-{2})?             # IE can understand comments without dashes
                      \[                  # Match the start ("[" is a metachar => escape it)
                          (?:(?!\]>).)*   # Match everything except "]>"
                      \]>                 # Match end
                  )
                  (
                      (?:
                          (?!<!\[endif\]-{2}?>)
                      .)*
                  )                     # Match everything except end of conditional comment
                  (
                      <!\[endif\]
                            (?:\2|(?=>))  # Use a trick to ensure that when dashes are captured they are...
                                          # matched at the end! Else make sure that the next char is a ">"!
                      >                   # Match the endif with the captured dashes
                  )
              /xis',
              function ($match) use ($placeholderContainer) {
                  if (!empty(preg_replace('/\s*/', '', $match[3]))) {
                      return $placeholderContainer->createPlaceholder($match[1]).$match[3].$placeholderContainer->createPlaceholder($match[4]);
                  } else {
                      return '';
                  }
              }, $contents);
      }
code: protected function setConditionalCommentsPlaceholder($contents, PlaceholderContainer $placeholderContainer)
      {
          return preg_replace_callback(
              '/
                  (
                      <!                  # Match the start of a comment
                      (-{2})?             # IE can understand comments without dashes
                      \[                  # Match the start ("[" is a metachar => escape it)
                          (?:(?!\]>).)*   # Match everything except "]>"
                      \]>                 # Match end
                  )
                  (
                      (?:
                          (?!<!\[endif\]-{2}?>)
                      .)*
                  )                     # Match everything except end of conditional comment
                  (
                      <!\[endif\]
                            (?:\2|(?=>))  # Use a trick to ensure that when dashes are captured they are...
                                          # matched at the end! Else make sure that the next char is a ">"!
                      >                   # Match the endif with the captured dashes
                  )
              /xis',
              function ($match) use ($placeholderContainer) {
                  if (!empty(preg_replace('/\s*/', '', $match[3]))) {
                      return $placeholderContainer->createPlaceholder($match[1]).$match[3].$placeholderContainer->createPlaceholder($match[4]);
                  } else {
                      return '';
                  }
              }, $contents);
      }
code_tokens: protected function setConditionalCommentsPlaceholder ( $ contents , PlaceholderContainer $ placeholderContainer ) { return preg_replace_callback ( '/
                  (
                      <!                  # Match the start of a comment
                      (-{2})?             # IE can understand comments without dashes
                      \[                  # Match the start ("[" is a metachar => escape it)
                          (?:(?!\]>).)*   # Match everything except "]>"
                      \]>                 # Match end
                  )
                  (
                      (?:
                          (?!<!\[endif\]-{2}?>)
                      .)*
                  )                     # Match everything except end of conditional comment
                  (
                      <!\[endif\]
                            (?:\2|(?=>))  # Use a trick to ensure that when dashes are captured they are...
                                          # matched at the end! Else make sure that the next char is a ">"!
                      >                   # Match the endif with the captured dashes
                  )
              /xis' , function ( $ match ) use ( $ placeholderContainer ) { if ( ! empty ( preg_replace ( '/\s*/' , '' , $ match [ 3 ] ) ) ) { return $ placeholderContainer -> createPlaceholder ( $ match [ 1 ] ) . $ match [ 3 ] . $ placeholderContainer -> createPlaceholder ( $ match [ 4 ] ) ; } else { return '' ; } } , $ contents ) ; }
docstring: Replace conditional placeholders used by Internet Explorer.
  
  @param string                                           $contents
  @param \ArjanSchouten\HtmlMinifier\PlaceholderContainer $placeholderContainer
  
  @return string
docstring_tokens: Replace conditional placeholders used by Internet Explorer .