or  tags.

		$prev_token_last_char = ""; # This is a cheat, used to get some context
									# for one-character tokens that consist of 
									# just a quote char. What we do is remember
									# the last character of the previous text
									# token, to use as context to curl single-
									# character quote tokens correctly.

		foreach ($tokens as $cur_token) {
			if ($cur_token[0] == "tag") {
				# Don't mess with quotes inside tags.
				$result .= $cur_token[1];
				if (preg_match('@<(/?)(?:'.$this->tags_to_skip.')[\s>]@', $cur_token[1], $matches)) {
					$in_pre = isset($matches[1]) && $matches[1] == '/' ? 0 : 1;
				}
			} else {
				$t = $cur_token[1];
				$last_char = substr($t, -1); # Remember last char of this token before processing.
				if (! $in_pre) {
					$t = $this->educate($t, $prev_token_last_char);
				}
				$prev_token_last_char = $last_char;
				$result .= $t;
			}
		}

		return $result;
	}


	function decodeEntitiesInConfiguration() {
	#
	#   Utility function that converts entities in configuration variables to
	#   UTF-8 characters.
	#
		$output_config_vars = array(
			'smart_doublequote_open',
			'smart_doublequote_close',
			'smart_singlequote_open',
			'smart_singlequote_close',
			'backtick_doublequote_open',
			'backtick_doublequote_close',
			'backtick_singlequote_open',
			'backtick_singlequote_close',
			'em_dash',
			'en_dash',
			'ellipsis',
		);
		foreach ($output_config_vars as $var) {
			$this->$var = html_entity_decode($this->$var);
		}
	}


	protected function educate($t, $prev_token_last_char) {
		$t = $this->processEscapes($t);

		if ($this->convert_quot) {
			$t = preg_replace('/"/', '"', $t);
		}

		if ($this->do_dashes) {
			if ($this->do_dashes == 1) $t = $this->educateDashes($t);
			if ($this->do_dashes == 2) $t = $this->educateDashesOldSchool($t);
			if ($this->do_dashes == 3) $t = $this->educateDashesOldSchoolInverted($t);
		}

		if ($this->do_ellipses) $t = $this->educateEllipses($t);

		# Note: backticks need to be processed before quotes.
		if ($this->do_backticks) {
			$t = $this->educateBackticks($t);
			if ($this->do_backticks == 2) $t = $this->educateSingleBackticks($t);
		}

		if ($this->do_quotes) {
			if ($t == "'") {
				# Special case: single-character ' token
				if (preg_match('/\S/', $prev_token_last_char)) {
					$t = $this->smart_singlequote_close;
				}
				else {
					$t = $this->smart_singlequote_open;
				}
			}
			else if ($t == '"') {
				# Special case: single-character " token
				if (preg_match('/\S/', $prev_token_last_char)) {
					$t = $this->smart_doublequote_close;
				}
				else {
					$t = $this->smart_doublequote_open;
				}
			}
			else {
				# Normal case:
				$t = $this->educateQuotes($t);
			}
		}

		if ($this->do_stupefy) $t = $this->stupefyEntities($t);
		
		return $t;
	}


	protected function educateQuotes($_) {
	#
	#   Parameter:  String.
	#
	#   Returns:    The string, with "educated" curly quote HTML entities.
	#
	#   Example input:  "Isn't this fun?"
	#   Example output: “Isn’t this fun?”
	#
		$dq_open  = $this->smart_doublequote_open;
		$dq_close = $this->smart_doublequote_close;
		$sq_open  = $this->smart_singlequote_open;
		$sq_close = $this->smart_singlequote_close;
	
		# Make our own "punctuation" character class, because the POSIX-style
		# [:PUNCT:] is only available in Perl 5.6 or later:
		$punct_class = "[!\"#\\$\\%'()*+,-.\\/:;<=>?\\@\\[\\\\\]\\^_`{|}~]";

		# Special case if the very first character is a quote
		# followed by punctuation at a non-word-break. Close the quotes by brute force:
		$_ = preg_replace(
			array("/^'(?=$punct_class\\B)/", "/^\"(?=$punct_class\\B)/"),
			array($sq_close,                 $dq_close), $_);

		# Special case for double sets of quotes, e.g.:
		#   
He said, "'Quoted' words in a larger quote."
		$_ = preg_replace(
			array("/\"'(?=\w)/",     "/'\"(?=\w)/"),
			array($dq_open.$sq_open, $sq_open.$dq_open), $_);

		# Special case for decade abbreviations (the '80s):
		$_ = preg_replace("/'(?=\\d{2}s)/", $sq_close, $_);

		$close_class = '[^\ \t\r\n\[\{\(\-]';
		$dec_dashes = '&\#8211;|&\#8212;';

		# Get most opening single quotes:
		$_ = preg_replace("{
			(
				\\s          |   # a whitespace char, or
				       |   # a non-breaking space entity, or
				--          |   # dashes, or
				&[mn]dash;  |   # named dash entities
				$dec_dashes |   # or decimal entities
				&\\#x201[34];    # or hex
			)
			'                   # the quote
			(?=\\w)              # followed by a word character
			}x", '\1'.$sq_open, $_);
		# Single closing quotes:
		$_ = preg_replace("{
			($close_class)?
			'
			(?(1)|          # If $1 captured, then do nothing;
			  (?=\\s | s\\b)  # otherwise, positive lookahead for a whitespace
			)               # char or an 's' at a word ending position. This
							# is a special case to handle something like:
							# \"Custer's Last Stand.\"
			}xi", '\1'.$sq_close, $_);

		# Any remaining single quotes should be opening ones:
		$_ = str_replace("'", $sq_open, $_);


		# Get most opening double quotes:
		$_ = preg_replace("{
			(
				\\s          |   # a whitespace char, or
				       |   # a non-breaking space entity, or
				--          |   # dashes, or
				&[mn]dash;  |   # named dash entities
				$dec_dashes |   # or decimal entities
				&\\#x201[34];    # or hex
			)
			\"                   # the quote
			(?=\\w)              # followed by a word character
			}x", '\1'.$dq_open, $_);

		# Double closing quotes:
		$_ = preg_replace("{
			($close_class)?
			\"
			(?(1)|(?=\\s))   # If $1 captured, then do nothing;
							   # if not, then make sure the next char is whitespace.
			}x", '\1'.$dq_close, $_);

		# Any remaining quotes should be opening ones.
		$_ = str_replace('"', $dq_open, $_);

		return $_;
	}


	protected function educateBackticks($_) {
	#
	#   Parameter:  String.
	#   Returns:    The string, with ``backticks'' -style double quotes
	#               translated into HTML curly quote entities.
	#
	#   Example input:  ``Isn't this fun?''
	#   Example output: “Isn't this fun?”
	#

		$_ = str_replace(array("``", "''",),
						 array($this->backtick_doublequote_open,
							   $this->backtick_doublequote_close), $_);
		return $_;
	}


	protected function educateSingleBackticks($_) {
	#
	#   Parameter:  String.
	#   Returns:    The string, with `backticks' -style single quotes
	#               translated into HTML curly quote entities.
	#
	#   Example input:  `Isn't this fun?'
	#   Example output: ‘Isn’t this fun?’
	#

		$_ = str_replace(array("`",       "'",),
						 array($this->backtick_singlequote_open,
							   $this->backtick_singlequote_close), $_);
		return $_;
	}


	protected function educateDashes($_) {
	#
	#   Parameter:  String.
	#
	#   Returns:    The string, with each instance of "--" translated to
	#               an em-dash HTML entity.
	#

		$_ = str_replace('--', $this->em_dash, $_);
		return $_;
	}


	protected function educateDashesOldSchool($_) {
	#
	#   Parameter:  String.
	#
	#   Returns:    The string, with each instance of "--" translated to
	#               an en-dash HTML entity, and each "---" translated to
	#               an em-dash HTML entity.
	#

		#                      em              en
		$_ = str_replace(array("---",          "--",),
						 array($this->em_dash, $this->en_dash), $_);
		return $_;
	}


	protected function educateDashesOldSchoolInverted($_) {
	#
	#   Parameter:  String.
	#
	#   Returns:    The string, with each instance of "--" translated to
	#               an em-dash HTML entity, and each "---" translated to
	#               an en-dash HTML entity. Two reasons why: First, unlike the
	#               en- and em-dash syntax supported by
	#               EducateDashesOldSchool(), it's compatible with existing
	#               entries written before SmartyPants 1.1, back when "--" was
	#               only used for em-dashes.  Second, em-dashes are more
	#               common than en-dashes, and so it sort of makes sense that
	#               the shortcut should be shorter to type. (Thanks to Aaron
	#               Swartz for the idea.)
	#

		#                      en              em
		$_ = str_replace(array("---",          "--",),
						 array($this->en_dash, $this->em_dash), $_);
		return $_;
	}


	protected function educateEllipses($_) {
	#
	#   Parameter:  String.
	#   Returns:    The string, with each instance of "..." translated to
	#               an ellipsis HTML entity. Also converts the case where
	#               there are spaces between the dots.
	#
	#   Example input:  Huh...?
	#   Example output: Huh…?
	#

		$_ = str_replace(array("...",     ". . .",), $this->ellipsis, $_);
		return $_;
	}


	protected function stupefyEntities($_) {
	#
	#   Parameter:  String.
	#   Returns:    The string, with each SmartyPants HTML entity translated to
	#               its ASCII counterpart.
	#
	#   Example input:  “Hello — world.”
	#   Example output: "Hello -- world."
	#

							#  en-dash    em-dash
		$_ = str_replace(array('–', '—'),
						 array('-',       '--'), $_);

		# single quote         open       close
		$_ = str_replace(array('‘', '’'), "'", $_);

		# double quote         open       close
		$_ = str_replace(array('“', '”'), '"', $_);

		$_ = str_replace('…', '...', $_); # ellipsis

		return $_;
	}


	protected function processEscapes($_) {
	#
	#   Parameter:  String.
	#   Returns:    The string, with after processing the following backslash
	#               escape sequences. This is useful if you want to force a "dumb"
	#               quote or other character to appear.
	#
	#               Escape  Value
	#               ------  -----
	#               \\      \
	#               \"      "
	#               \'      '
	#               \.      .
	#               \-      -
	#               \`      `
	#
		$_ = str_replace(
			array('\\\\',  '\"',    "\'",    '\.',    '\-',    '\`'),
			array('\', '"', ''', '.', '-', '`'), $_);

		return $_;
	}


	protected function tokenizeHTML($str) {
	#
	#   Parameter:  String containing HTML markup.
	#   Returns:    An array of the tokens comprising the input
	#               string. Each token is either a tag (possibly with nested,
	#               tags contained therein, such as , or a
	#               run of text between tags. Each element of the array is a
	#               two-element array; the first is either 'tag' or 'text';
	#               the second is the actual value.
	#
	#
	#   Regular expression derived from the _tokenize() subroutine in 
	#   Brad Choate's MTRegex plugin.
	#   
	#
		$index = 0;
		$tokens = array();

		$match = '(?s:)|'.	# comment
				 '(?s:<\?.*?\?>)|'.				# processing instruction
												# regular tags
				 '(?:<[/!$]?[-a-zA-Z0-9:]+\b(?>[^"\'>]+|"[^"]*"|\'[^\']*\')*>)'; 

		$parts = preg_split("{($match)}", $str, -1, PREG_SPLIT_DELIM_CAPTURE);

		foreach ($parts as $part) {
			if (++$index % 2 && $part != '') 
				$tokens[] = array('text', $part);
			else
				$tokens[] = array('tag', $part);
		}
		return $tokens;
	}

}