<?php
/*
Forgivingly lexes SGML style documents, aka HTML, XML, XHMTML, you name it.
TODO:
* Reread the XML spec and make sure I got everything right
* Add support for CDATA sections
* Have comments output with the leading and trailing --s
* Optimize and benchmark
* Check MF_Text behavior: shouldn't the info in there be raw (entities parsed?)
*/
class HTML_Lexer
{
function nextQuote($string, $offset = 0) {
$quotes = array('"', "'");
return $this->next($string, $quotes, $offset);
}
function nextWhiteSpace($string, $offset = 0) {
$spaces = array(chr(0x20), chr(0x9), chr(0xD), chr(0xA));
return $this->next($string, $spaces, $offset);
}
function next($haystack, $needles, $offset = 0) {
if (is_string($needles)) {
$string_needles = $needles;
$needles = array();
$size = strlen($string_needles);
for ($i = 0; $i < $size; $i++) {
$needles[] = $string_needles{$i};
}
}
$positions = array();
foreach ($needles as $needle) {
$position = strpos($haystack, $needle, $offset);
if ($position !== false) {
$positions[] = $position;
}
}
return empty($positions) ? false : min($positions);
}
function tokenizeHTML($string) {
// some quick checking (if empty, return empty)
$string = (string) $string;
if ($string == '') return array();
$cursor = 0; // our location in the text
$inside_tag = false; // whether or not we're parsing the inside of a tag
$array = array(); // result array
// infinite loop protection
// has to be pretty big, since html docs can be big
// we're allow two hundred thousand tags... more than enough?
$loops = 0;
while(true) {
// infinite loop protection
if (++$loops > 200000) return array();
$position_next_lt = strpos($string, '<', $cursor);
$position_next_gt = strpos($string, '>', $cursor);
// triggers on "<b>asdf</b>" but not "asdf <b></b>"
if ($position_next_lt === $cursor) {
$inside_tag = true;
$cursor++;
}
if (!$inside_tag && $position_next_lt !== false) {
// We are not inside tag and there still is another tag to parse
$array[] = new MF_Text(html_entity_decode(substr($string, $cursor, $position_next_lt - $cursor)));
$cursor = $position_next_lt + 1;
$inside_tag = true;
continue;
} elseif (!$inside_tag) {
// We are not inside tag but there are no more tags
// If we're already at the end, break
if ($cursor === strlen($string)) break;
// Create Text of rest of string
$array[] = new MF_Text(html_entity_decode(substr($string, $cursor)));
break;
} elseif ($inside_tag && $position_next_gt !== false) {
// We are in tag and it is well formed
// Grab the internals of the tag
$segment = substr($string, $cursor, $position_next_gt - $cursor);
// Check if it's a comment
if (substr($segment,0,3) == '!--' && substr($segment,strlen($segment)-2,2) == '--') {
$array[] = new MF_Comment(substr($segment,3,strlen($segment)-5));
$inside_tag = false;
$cursor = $position_next_gt + 1;
continue;
}
// Check if it's an end tag
$is_end_tag = (strpos($segment,'/') === 0);
if ($is_end_tag) {
$type = substr($segment, 1);
$array[] = new MF_EndTag($type);
$inside_tag = false;
$cursor = $position_next_gt + 1;
continue;
}
// Check if it is explicitly self closing, if so, remove
// trailing slash. Remember, we could have a tag like <br>, so
// any later token processing scripts must convert improperly
// classified EmptyTags from StartTags.
$is_self_closing = (strpos($segment,'/') === strlen($segment) - 1);
if ($is_self_closing) {
$segment = substr($segment, 0, strlen($segment) - 1);
}
// Check if there are any attributes
$position_first_space = $this->nextWhiteSpace($segment);
if ($position_first_space === false) {
if ($is_self_closing) {
$array[] = new MF_EmptyTag($segment);
} else {
$array[] = new MF_StartTag($segment, array());
}
$inside_tag = false;
$cursor = $position_next_gt + 1;
continue;
}
// Grab out all the data
$type = substr($segment, 0, $position_first_space);
$attribute_string = trim(substr($segment, $position_first_space));
$attributes = $this->tokenizeAttributeString($attribute_string);
if ($is_self_closing) {
$array[] = new MF_EmptyTag($type, $attributes);
} else {
$array[] = new MF_StartTag($type, $attributes);
}
$cursor = $position_next_gt + 1;
$inside_tag = false;
continue;
} else {
$array[] = new MF_Text('<' . html_entity_decode(substr($string, $cursor)));
break;
}
break;
}
return $array;
}
function tokenizeAttributeString($string) {
$string = (string) $string;
if ($string == '') return array();
$array = array();
$cursor = 0;
$in_value = false;
$i = 0;
$size = strlen($string);
// if we have unquoted attributes, the parser expects a terminating
// space, so let's guarantee that there's always a terminating space.
$string .= ' ';
// infinite loop protection
$loops = 0;
while(true) {
// infinite loop protection
// if we've looped 1000 times, abort. Nothing good can come of this
if (++$loops > 1000) return array();
if ($cursor >= $size) {
break;
}
$position_next_space = $this->nextWhiteSpace($string, $cursor);
//scroll to the last whitespace before text
while ($position_next_space === $cursor) {
$cursor++;
$position_next_space = $this->nextWhiteSpace($string, $cursor);
}
$position_next_equal = strpos($string, '=', $cursor);
if ($position_next_equal !== false &&
($position_next_equal < $position_next_space ||
$position_next_space === false)) {
//attr="asdf"
// grab the key
$key = trim(substr($string, $cursor, $position_next_equal - $cursor));
// set cursor right after the equal sign
$cursor = $position_next_equal + 1;
// consume all spaces after the equal sign
$position_next_space = $this->nextWhiteSpace($string, $cursor);
while ($position_next_space === $cursor) {
$cursor++;
$position_next_space = $this->nextWhiteSpace($string, $cursor);
}
// if we've hit the end, assign the key an empty value and abort
if ($cursor >= $size) {
$array[$key] = '';
break;
}
// find the next quote
$position_next_quote = $this->nextQuote($string, $cursor);
// if the quote is not where the cursor is, we're dealing
// with an unquoted attribute
if ($position_next_quote !== $cursor) {
if ($key) {
$array[$key] = trim(substr($string, $cursor,
$position_next_space - $cursor));
}
$cursor = $position_next_space + 1;
continue;
}
// otherwise, regular attribute
$quote = $string{$position_next_quote};
$position_end_quote = strpos($string, $quote, $position_next_quote + 1);
// check if the ending quote is missing
if ($position_end_quote === false) {
// it is, assign it to the end of the string
$position_end_quote = $size;
}
$value = substr($string, $position_next_quote + 1,
$position_end_quote - $position_next_quote - 1);
if ($key) {
$array[$key] = html_entity_decode($value);
}
$cursor = $position_end_quote + 1;
} else {
//boolattr
if ($position_next_space === false) {
$position_next_space = $size;
}
$key = substr($string, $cursor, $position_next_space - $cursor);
if ($key) {
$array[$key] = $key;
}
$cursor = $position_next_space + 1;
}
}
return $array;
}
}
// uses the PEAR class XML_HTMLSax3 to parse XML
// only shares the tokenizeHTML() function
class HTML_Lexer_Sax extends HTML_Lexer
{
var $tokens = array();
function tokenizeHTML($html) {
$this->tokens = array();
$parser=& new XML_HTMLSax3();
$parser->set_object($this);
$parser->set_element_handler('openHandler','closeHandler');
$parser->set_data_handler('dataHandler');
$parser->set_escape_handler('escapeHandler');
$parser->set_option('XML_OPTION_ENTITIES_PARSED', 1);
$parser->parse($html);
return $this->tokens;
}
function openHandler(&$parser, $name, $attrs, $closed) {
if ($closed) {
$this->tokens[] = new MF_EmptyTag($name, $attrs);
} else {
$this->tokens[] = new MF_StartTag($name, $attrs);
}
return true;
}
function closeHandler(&$parser, $name) {
// HTMLSax3 seems to always send empty tags an extra close tag
// check and ignore if you see it:
// [TESTME] to make sure it doesn't overreach
if (is_a($this->tokens[count($this->tokens)-1], 'MF_EmptyTag')) {
return true;
}
$this->tokens[] = new MF_EndTag($name);
return true;
}
function dataHandler(&$parser, $data) {
$this->tokens[] = new MF_Text($data);
return true;
}
function escapeHandler(&$parser, $data) {
if (strpos($data, '-') === 0) {
$this->tokens[] = new MF_Comment($data);
}
return true;
}
}
?>