diff vendor/masterminds/html5/src/HTML5/Parser/Tokenizer.php @ 0:4c8ae668cc8c

Initial import (non-working)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vendor/masterminds/html5/src/HTML5/Parser/Tokenizer.php	Wed Nov 29 16:09:58 2017 +0000
@@ -0,0 +1,1117 @@
+<?php
+namespace Masterminds\HTML5\Parser;
+
+use Masterminds\HTML5\Elements;
+
+/**
+ * The HTML5 tokenizer.
+ *
+ * The tokenizer's role is reading data from the scanner and gathering it into
+ * semantic units. From the tokenizer, data is emitted to an event handler,
+ * which may (for example) create a DOM tree.
+ *
+ * The HTML5 specification has a detailed explanation of tokenizing HTML5. We
+ * follow that specification to the maximum extent that we can. If you find
+ * a discrepancy that is not documented, please file a bug and/or submit a
+ * patch.
+ *
+ * This tokenizer is implemented as a recursive descent parser.
+ *
+ * Within the API documentation, you may see references to the specific section
+ * of the HTML5 spec that the code attempts to reproduce. Example: 8.2.4.1.
+ * This refers to section 8.2.4.1 of the HTML5 CR specification.
+ *
+ * @see http://www.w3.org/TR/2012/CR-html5-20121217/
+ */
+class Tokenizer
+{
+
+    protected $scanner;
+
+    protected $events;
+
+    protected $tok;
+
+    /**
+     * Buffer for text.
+     */
+    protected $text = '';
+
+    // When this goes to false, the parser stops.
+    protected $carryOn = true;
+
+    protected $textMode = 0; // TEXTMODE_NORMAL;
+    protected $untilTag = null;
+
+    const CONFORMANT_XML = 'xml';
+    const CONFORMANT_HTML = 'html';
+    protected $mode = self::CONFORMANT_HTML;
+
+    const WHITE = "\t\n\f ";
+
+    /**
+     * Create a new tokenizer.
+     *
+     * Typically, parsing a document involves creating a new tokenizer, giving
+     * it a scanner (input) and an event handler (output), and then calling
+     * the Tokenizer::parse() method.`
+     *
+     * @param \Masterminds\HTML5\Parser\Scanner $scanner
+     *            A scanner initialized with an input stream.
+     * @param \Masterminds\HTML5\Parser\EventHandler $eventHandler
+     *            An event handler, initialized and ready to receive
+     *            events.
+     * @param string $mode
+     */
+    public function __construct($scanner, $eventHandler, $mode = self::CONFORMANT_HTML)
+    {
+        $this->scanner = $scanner;
+        $this->events = $eventHandler;
+        $this->mode = $mode;
+    }
+
+    /**
+     * Begin parsing.
+     *
+     * This will begin scanning the document, tokenizing as it goes.
+     * Tokens are emitted into the event handler.
+     *
+     * Tokenizing will continue until the document is completely
+     * read. Errors are emitted into the event handler, but
+     * the parser will attempt to continue parsing until the
+     * entire input stream is read.
+     */
+    public function parse()
+    {
+        do {
+            $this->consumeData();
+            // FIXME: Add infinite loop protection.
+        } while ($this->carryOn);
+    }
+
+    /**
+     * Set the text mode for the character data reader.
+     *
+     * HTML5 defines three different modes for reading text:
+     * - Normal: Read until a tag is encountered.
+     * - RCDATA: Read until a tag is encountered, but skip a few otherwise-
+     * special characters.
+     * - Raw: Read until a special closing tag is encountered (viz. pre, script)
+     *
+     * This allows those modes to be set.
+     *
+     * Normally, setting is done by the event handler via a special return code on
+     * startTag(), but it can also be set manually using this function.
+     *
+     * @param integer $textmode
+     *            One of Elements::TEXT_*
+     * @param string $untilTag
+     *            The tag that should stop RAW or RCDATA mode. Normal mode does not
+     *            use this indicator.
+     */
+    public function setTextMode($textmode, $untilTag = null)
+    {
+        $this->textMode = $textmode & (Elements::TEXT_RAW | Elements::TEXT_RCDATA);
+        $this->untilTag = $untilTag;
+    }
+
+    /**
+     * Consume a character and make a move.
+     * HTML5 8.2.4.1
+     */
+    protected function consumeData()
+    {
+        // Character Ref
+        /*
+         * $this->characterReference() || $this->tagOpen() || $this->eof() || $this->characterData();
+         */
+        $this->characterReference();
+        $this->tagOpen();
+        $this->eof();
+        $this->characterData();
+
+        return $this->carryOn;
+    }
+
+    /**
+     * Parse anything that looks like character data.
+     *
+     * Different rules apply based on the current text mode.
+     *
+     * @see Elements::TEXT_RAW Elements::TEXT_RCDATA.
+     */
+    protected function characterData()
+    {
+        $tok = $this->scanner->current();
+        if ($tok === false) {
+            return false;
+        }
+        switch ($this->textMode) {
+            case Elements::TEXT_RAW:
+                return $this->rawText();
+            case Elements::TEXT_RCDATA:
+                return $this->rcdata();
+            default:
+                if (strspn($tok, "<&")) {
+                    return false;
+                }
+                return $this->text();
+        }
+    }
+
+    /**
+     * This buffers the current token as character data.
+     */
+    protected function text()
+    {
+        $tok = $this->scanner->current();
+
+        // This should never happen...
+        if ($tok === false) {
+            return false;
+        }
+        // Null
+        if ($tok === "\00") {
+            $this->parseError("Received null character.");
+        }
+        // fprintf(STDOUT, "Writing '%s'", $tok);
+        $this->buffer($tok);
+        $this->scanner->next();
+        return true;
+    }
+
+    /**
+     * Read text in RAW mode.
+     */
+    protected function rawText()
+    {
+        if (is_null($this->untilTag)) {
+            return $this->text();
+        }
+        $sequence = '</' . $this->untilTag . '>';
+        $txt = $this->readUntilSequence($sequence);
+        $this->events->text($txt);
+        $this->setTextMode(0);
+        return $this->endTag();
+    }
+
+    /**
+     * Read text in RCDATA mode.
+     */
+    protected function rcdata()
+    {
+        if (is_null($this->untilTag)) {
+            return $this->text();
+        }
+        $sequence = '</' . $this->untilTag;
+        $txt = '';
+        $tok = $this->scanner->current();
+
+        $caseSensitive = !Elements::isHtml5Element($this->untilTag);
+        while ($tok !== false && ! ($tok == '<' && ($this->sequenceMatches($sequence, $caseSensitive)))) {
+            if ($tok == '&') {
+                $txt .= $this->decodeCharacterReference();
+                $tok = $this->scanner->current();
+            } else {
+                $txt .= $tok;
+                $tok = $this->scanner->next();
+            }
+        }
+        $len = strlen($sequence);
+        $this->scanner->consume($len);
+        $len += strlen($this->scanner->whitespace());
+        if ($this->scanner->current() !== '>') {
+            $this->parseError("Unclosed RCDATA end tag");
+        }
+        $this->scanner->unconsume($len);
+        $this->events->text($txt);
+        $this->setTextMode(0);
+        return $this->endTag();
+    }
+
+    /**
+     * If the document is read, emit an EOF event.
+     */
+    protected function eof()
+    {
+        if ($this->scanner->current() === false) {
+            // fprintf(STDOUT, "EOF");
+            $this->flushBuffer();
+            $this->events->eof();
+            $this->carryOn = false;
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Handle character references (aka entities).
+     *
+     * This version is specific to PCDATA, as it buffers data into the
+     * text buffer. For a generic version, see decodeCharacterReference().
+     *
+     * HTML5 8.2.4.2
+     */
+    protected function characterReference()
+    {
+        $ref = $this->decodeCharacterReference();
+        if ($ref !== false) {
+            $this->buffer($ref);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Emit a tagStart event on encountering a tag.
+     *
+     * 8.2.4.8
+     */
+    protected function tagOpen()
+    {
+        if ($this->scanner->current() != '<') {
+            return false;
+        }
+
+        // Any buffered text data can go out now.
+        $this->flushBuffer();
+
+        $this->scanner->next();
+
+        return $this->markupDeclaration() || $this->endTag() || $this->processingInstruction() || $this->tagName() ||
+          /*  This always returns false. */
+          $this->parseError("Illegal tag opening") || $this->characterData();
+    }
+
+    /**
+     * Look for markup.
+     */
+    protected function markupDeclaration()
+    {
+        if ($this->scanner->current() != '!') {
+            return false;
+        }
+
+        $tok = $this->scanner->next();
+
+        // Comment:
+        if ($tok == '-' && $this->scanner->peek() == '-') {
+            $this->scanner->next(); // Consume the other '-'
+            $this->scanner->next(); // Next char.
+            return $this->comment();
+        }
+
+        elseif ($tok == 'D' || $tok == 'd') { // Doctype
+            return $this->doctype();
+        }
+
+        elseif ($tok == '[') { // CDATA section
+            return $this->cdataSection();
+        }
+
+        // FINISH
+        $this->parseError("Expected <!--, <![CDATA[, or <!DOCTYPE. Got <!%s", $tok);
+        $this->bogusComment('<!');
+        return true;
+    }
+
+    /**
+     * Consume an end tag.
+     * 8.2.4.9
+     */
+    protected function endTag()
+    {
+        if ($this->scanner->current() != '/') {
+            return false;
+        }
+        $tok = $this->scanner->next();
+
+        // a-zA-Z -> tagname
+        // > -> parse error
+        // EOF -> parse error
+        // -> parse error
+        if (! ctype_alpha($tok)) {
+            $this->parseError("Expected tag name, got '%s'", $tok);
+            if ($tok == "\0" || $tok === false) {
+                return false;
+            }
+            return $this->bogusComment('</');
+        }
+
+        $name = $this->scanner->charsUntil("\n\f \t>");
+        $name = $this->mode === self::CONFORMANT_XML ? $name: strtolower($name);
+        // Trash whitespace.
+        $this->scanner->whitespace();
+
+        if ($this->scanner->current() != '>') {
+            $this->parseError("Expected >, got '%s'", $this->scanner->current());
+            // We just trash stuff until we get to the next tag close.
+            $this->scanner->charsUntil('>');
+        }
+
+        $this->events->endTag($name);
+        $this->scanner->next();
+        return true;
+    }
+
+    /**
+     * Consume a tag name and body.
+     * 8.2.4.10
+     */
+    protected function tagName()
+    {
+        $tok = $this->scanner->current();
+        if (! ctype_alpha($tok)) {
+            return false;
+        }
+
+        // We know this is at least one char.
+        $name = $this->scanner->charsWhile(":_-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz");
+        $name = $this->mode === self::CONFORMANT_XML ? $name : strtolower($name);
+        $attributes = array();
+        $selfClose = false;
+
+        // Handle attribute parse exceptions here so that we can
+        // react by trying to build a sensible parse tree.
+        try {
+            do {
+                $this->scanner->whitespace();
+                $this->attribute($attributes);
+            } while (! $this->isTagEnd($selfClose));
+        } catch (ParseError $e) {
+            $selfClose = false;
+        }
+
+        $mode = $this->events->startTag($name, $attributes, $selfClose);
+        // Should we do this? What does this buy that selfClose doesn't?
+        if ($selfClose) {
+            $this->events->endTag($name);
+        } elseif (is_int($mode)) {
+            // fprintf(STDOUT, "Event response says move into mode %d for tag %s", $mode, $name);
+            $this->setTextMode($mode, $name);
+        }
+
+        $this->scanner->next();
+
+        return true;
+    }
+
+    /**
+     * Check if the scanner has reached the end of a tag.
+     */
+    protected function isTagEnd(&$selfClose)
+    {
+        $tok = $this->scanner->current();
+        if ($tok == '/') {
+            $this->scanner->next();
+            $this->scanner->whitespace();
+            $tok = $this->scanner->current();
+
+            if ($tok == '>') {
+                $selfClose = true;
+                return true;
+            }
+            if ($tok === false) {
+                $this->parseError("Unexpected EOF inside of tag.");
+                return true;
+            }
+            // Basically, we skip the / token and go on.
+            // See 8.2.4.43.
+            $this->parseError("Unexpected '%s' inside of a tag.", $tok);
+            return false;
+        }
+
+        if ($tok == '>') {
+            return true;
+        }
+        if ($tok === false) {
+            $this->parseError("Unexpected EOF inside of tag.");
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Parse attributes from inside of a tag.
+     */
+    protected function attribute(&$attributes)
+    {
+        $tok = $this->scanner->current();
+        if ($tok == '/' || $tok == '>' || $tok === false) {
+            return false;
+        }
+
+        if ($tok == '<') {
+            $this->parseError("Unexepcted '<' inside of attributes list.");
+            // Push the < back onto the stack.
+            $this->scanner->unconsume();
+            // Let the caller figure out how to handle this.
+            throw new ParseError("Start tag inside of attribute.");
+        }
+
+        $name = strtolower($this->scanner->charsUntil("/>=\n\f\t "));
+
+        if (strlen($name) == 0) {
+            $this->parseError("Expected an attribute name, got %s.", $this->scanner->current());
+            // Really, only '=' can be the char here. Everything else gets absorbed
+            // under one rule or another.
+            $name = $this->scanner->current();
+            $this->scanner->next();
+        }
+
+        $isValidAttribute = true;
+        // Attribute names can contain most Unicode characters for HTML5.
+        // But method "DOMElement::setAttribute" is throwing exception
+        // because of it's own internal restriction so these have to be filtered.
+        // see issue #23: https://github.com/Masterminds/html5-php/issues/23
+        // and http://www.w3.org/TR/2011/WD-html5-20110525/syntax.html#syntax-attribute-name
+        if (preg_match("/[\x1-\x2C\\/\x3B-\x40\x5B-\x5E\x60\x7B-\x7F]/u", $name)) {
+            $this->parseError("Unexpected characters in attribute name: %s", $name);
+            $isValidAttribute = false;
+        }         // There is no limitation for 1st character in HTML5.
+        // But method "DOMElement::setAttribute" is throwing exception for the
+        // characters below so they have to be filtered.
+        // see issue #23: https://github.com/Masterminds/html5-php/issues/23
+        // and http://www.w3.org/TR/2011/WD-html5-20110525/syntax.html#syntax-attribute-name
+        else
+            if (preg_match("/^[0-9.-]/u", $name)) {
+                $this->parseError("Unexpected character at the begining of attribute name: %s", $name);
+                $isValidAttribute = false;
+            }
+        // 8.1.2.3
+        $this->scanner->whitespace();
+
+        $val = $this->attributeValue();
+        if ($isValidAttribute) {
+            $attributes[$name] = $val;
+        }
+        return true;
+    }
+
+    /**
+     * Consume an attribute value.
+     * 8.2.4.37 and after.
+     */
+    protected function attributeValue()
+    {
+        if ($this->scanner->current() != '=') {
+            return null;
+        }
+        $this->scanner->next();
+        // 8.1.2.3
+        $this->scanner->whitespace();
+
+        $tok = $this->scanner->current();
+        switch ($tok) {
+            case "\n":
+            case "\f":
+            case " ":
+            case "\t":
+                // Whitespace here indicates an empty value.
+                return null;
+            case '"':
+            case "'":
+                $this->scanner->next();
+                return $this->quotedAttributeValue($tok);
+            case '>':
+                // case '/': // 8.2.4.37 seems to allow foo=/ as a valid attr.
+                $this->parseError("Expected attribute value, got tag end.");
+                return null;
+            case '=':
+            case '`':
+                $this->parseError("Expecting quotes, got %s.", $tok);
+                return $this->unquotedAttributeValue();
+            default:
+                return $this->unquotedAttributeValue();
+        }
+    }
+
+    /**
+     * Get an attribute value string.
+     *
+     * @param string $quote
+     *            IMPORTANT: This is a series of chars! Any one of which will be considered
+     *            termination of an attribute's value. E.g. "\"'" will stop at either
+     *            ' or ".
+     * @return string The attribute value.
+     */
+    protected function quotedAttributeValue($quote)
+    {
+        $stoplist = "\f" . $quote;
+        $val = '';
+
+        while (true) {
+            $tokens = $this->scanner->charsUntil($stoplist.'&');
+            if ($tokens !== false) {
+                $val .= $tokens;
+            } else {
+                break;
+            }
+
+            $tok = $this->scanner->current();
+            if ($tok == '&') {
+                $val .= $this->decodeCharacterReference(true, $tok);
+                continue;
+            }
+            break;
+        }
+        $this->scanner->next();
+        return $val;
+    }
+
+    protected function unquotedAttributeValue()
+    {
+        $stoplist = "\t\n\f >";
+        $val = '';
+        $tok = $this->scanner->current();
+        while (strspn($tok, $stoplist) == 0 && $tok !== false) {
+            if ($tok == '&') {
+                $val .= $this->decodeCharacterReference(true);
+                $tok = $this->scanner->current();
+            } else {
+                if (strspn($tok, "\"'<=`") > 0) {
+                    $this->parseError("Unexpected chars in unquoted attribute value %s", $tok);
+                }
+                $val .= $tok;
+                $tok = $this->scanner->next();
+            }
+        }
+        return $val;
+    }
+
+    /**
+     * Consume malformed markup as if it were a comment.
+     * 8.2.4.44
+     *
+     * The spec requires that the ENTIRE tag-like thing be enclosed inside of
+     * the comment. So this will generate comments like:
+     *
+     * &lt;!--&lt/+foo&gt;--&gt;
+     *
+     * @param string $leading
+     *            Prepend any leading characters. This essentially
+     *            negates the need to backtrack, but it's sort of
+     *            a hack.
+     */
+    protected function bogusComment($leading = '')
+    {
+        $comment = $leading;
+        $tokens = $this->scanner->charsUntil('>');
+        if ($tokens !== false) {
+            $comment .= $tokens;
+        }
+        $tok = $this->scanner->current();
+        if ($tok !== false) {
+            $comment .= $tok;
+        }
+
+        $this->flushBuffer();
+        $this->events->comment($comment);
+        $this->scanner->next();
+
+        return true;
+    }
+
+    /**
+     * Read a comment.
+     *
+     * Expects the first tok to be inside of the comment.
+     */
+    protected function comment()
+    {
+        $tok = $this->scanner->current();
+        $comment = '';
+
+        // <!-->. Emit an empty comment because 8.2.4.46 says to.
+        if ($tok == '>') {
+            // Parse error. Emit the comment token.
+            $this->parseError("Expected comment data, got '>'");
+            $this->events->comment('');
+            $this->scanner->next();
+            return true;
+        }
+
+        // Replace NULL with the replacement char.
+        if ($tok == "\0") {
+            $tok = UTF8Utils::FFFD;
+        }
+        while (! $this->isCommentEnd()) {
+            $comment .= $tok;
+            $tok = $this->scanner->next();
+        }
+
+        $this->events->comment($comment);
+        $this->scanner->next();
+        return true;
+    }
+
+    /**
+     * Check if the scanner has reached the end of a comment.
+     */
+    protected function isCommentEnd()
+    {
+        $tok = $this->scanner->current();
+
+        // EOF
+        if ($tok === false) {
+            // Hit the end.
+            $this->parseError("Unexpected EOF in a comment.");
+            return true;
+        }
+
+        // If it doesn't start with -, not the end.
+        if ($tok != '-') {
+            return false;
+        }
+
+        // Advance one, and test for '->'
+        if ($this->scanner->next() == '-' && $this->scanner->peek() == '>') {
+            $this->scanner->next(); // Consume the last '>'
+            return true;
+        }
+        // Unread '-';
+        $this->scanner->unconsume(1);
+        return false;
+    }
+
+    /**
+     * Parse a DOCTYPE.
+     *
+     * Parse a DOCTYPE declaration. This method has strong bearing on whether or
+     * not Quirksmode is enabled on the event handler.
+     *
+     * @todo This method is a little long. Should probably refactor.
+     */
+    protected function doctype()
+    {
+        if (strcasecmp($this->scanner->current(), 'D')) {
+            return false;
+        }
+        // Check that string is DOCTYPE.
+        $chars = $this->scanner->charsWhile("DOCTYPEdoctype");
+        if (strcasecmp($chars, 'DOCTYPE')) {
+            $this->parseError('Expected DOCTYPE, got %s', $chars);
+            return $this->bogusComment('<!' . $chars);
+        }
+
+        $this->scanner->whitespace();
+        $tok = $this->scanner->current();
+
+        // EOF: die.
+        if ($tok === false) {
+            $this->events->doctype('html5', EventHandler::DOCTYPE_NONE, '', true);
+            return $this->eof();
+        }
+
+        $doctypeName = '';
+
+        // NULL char: convert.
+        if ($tok === "\0") {
+            $this->parseError("Unexpected null character in DOCTYPE.");
+            $doctypeName .= UTF8::FFFD;
+            $tok = $this->scanner->next();
+        }
+
+        $stop = " \n\f>";
+        $doctypeName = $this->scanner->charsUntil($stop);
+        // Lowercase ASCII, replace \0 with FFFD
+        $doctypeName = strtolower(strtr($doctypeName, "\0", UTF8Utils::FFFD));
+
+        $tok = $this->scanner->current();
+
+        // If false, emit a parse error, DOCTYPE, and return.
+        if ($tok === false) {
+            $this->parseError('Unexpected EOF in DOCTYPE declaration.');
+            $this->events->doctype($doctypeName, EventHandler::DOCTYPE_NONE, null, true);
+            return true;
+        }
+
+        // Short DOCTYPE, like <!DOCTYPE html>
+        if ($tok == '>') {
+            // DOCTYPE without a name.
+            if (strlen($doctypeName) == 0) {
+                $this->parseError("Expected a DOCTYPE name. Got nothing.");
+                $this->events->doctype($doctypeName, 0, null, true);
+                $this->scanner->next();
+                return true;
+            }
+            $this->events->doctype($doctypeName);
+            $this->scanner->next();
+            return true;
+        }
+        $this->scanner->whitespace();
+
+        $pub = strtoupper($this->scanner->getAsciiAlpha());
+        $white = strlen($this->scanner->whitespace());
+
+        // Get ID, and flag it as pub or system.
+        if (($pub == 'PUBLIC' || $pub == 'SYSTEM') && $white > 0) {
+            // Get the sys ID.
+            $type = $pub == 'PUBLIC' ? EventHandler::DOCTYPE_PUBLIC : EventHandler::DOCTYPE_SYSTEM;
+            $id = $this->quotedString("\0>");
+            if ($id === false) {
+                $this->events->doctype($doctypeName, $type, $pub, false);
+                return false;
+            }
+
+            // Premature EOF.
+            if ($this->scanner->current() === false) {
+                $this->parseError("Unexpected EOF in DOCTYPE");
+                $this->events->doctype($doctypeName, $type, $id, true);
+                return true;
+            }
+
+            // Well-formed complete DOCTYPE.
+            $this->scanner->whitespace();
+            if ($this->scanner->current() == '>') {
+                $this->events->doctype($doctypeName, $type, $id, false);
+                $this->scanner->next();
+                return true;
+            }
+
+            // If we get here, we have <!DOCTYPE foo PUBLIC "bar" SOME_JUNK
+            // Throw away the junk, parse error, quirks mode, return true.
+            $this->scanner->charsUntil(">");
+            $this->parseError("Malformed DOCTYPE.");
+            $this->events->doctype($doctypeName, $type, $id, true);
+            $this->scanner->next();
+            return true;
+        }
+
+        // Else it's a bogus DOCTYPE.
+        // Consume to > and trash.
+        $this->scanner->charsUntil('>');
+
+        $this->parseError("Expected PUBLIC or SYSTEM. Got %s.", $pub);
+        $this->events->doctype($doctypeName, 0, null, true);
+        $this->scanner->next();
+        return true;
+    }
+
+    /**
+     * Utility for reading a quoted string.
+     *
+     * @param string $stopchars
+     *            Characters (in addition to a close-quote) that should stop the string.
+     *            E.g. sometimes '>' is higher precedence than '"' or "'".
+     * @return mixed String if one is found (quotations omitted)
+     */
+    protected function quotedString($stopchars)
+    {
+        $tok = $this->scanner->current();
+        if ($tok == '"' || $tok == "'") {
+            $this->scanner->next();
+            $ret = $this->scanner->charsUntil($tok . $stopchars);
+            if ($this->scanner->current() == $tok) {
+                $this->scanner->next();
+            } else {
+                // Parse error because no close quote.
+                $this->parseError("Expected %s, got %s", $tok, $this->scanner->current());
+            }
+            return $ret;
+        }
+        return false;
+    }
+
+    /**
+     * Handle a CDATA section.
+     */
+    protected function cdataSection()
+    {
+        if ($this->scanner->current() != '[') {
+            return false;
+        }
+        $cdata = '';
+        $this->scanner->next();
+
+        $chars = $this->scanner->charsWhile('CDAT');
+        if ($chars != 'CDATA' || $this->scanner->current() != '[') {
+            $this->parseError('Expected [CDATA[, got %s', $chars);
+            return $this->bogusComment('<![' . $chars);
+        }
+
+        $tok = $this->scanner->next();
+        do {
+            if ($tok === false) {
+                $this->parseError('Unexpected EOF inside CDATA.');
+                $this->bogusComment('<![CDATA[' . $cdata);
+                return true;
+            }
+            $cdata .= $tok;
+            $tok = $this->scanner->next();
+        } while (! $this->sequenceMatches(']]>'));
+
+        // Consume ]]>
+        $this->scanner->consume(3);
+
+        $this->events->cdata($cdata);
+        return true;
+    }
+
+    // ================================================================
+    // Non-HTML5
+    // ================================================================
+    /**
+     * Handle a processing instruction.
+     *
+     * XML processing instructions are supposed to be ignored in HTML5,
+     * treated as "bogus comments". However, since we're not a user
+     * agent, we allow them. We consume until ?> and then issue a
+     * EventListener::processingInstruction() event.
+     */
+    protected function processingInstruction()
+    {
+        if ($this->scanner->current() != '?') {
+            return false;
+        }
+
+        $tok = $this->scanner->next();
+        $procName = $this->scanner->getAsciiAlpha();
+        $white = strlen($this->scanner->whitespace());
+
+        // If not a PI, send to bogusComment.
+        if (strlen($procName) == 0 || $white == 0 || $this->scanner->current() == false) {
+            $this->parseError("Expected processing instruction name, got $tok");
+            $this->bogusComment('<?' . $tok . $procName);
+            return true;
+        }
+
+        $data = '';
+        // As long as it's not the case that the next two chars are ? and >.
+        while (! ($this->scanner->current() == '?' && $this->scanner->peek() == '>')) {
+            $data .= $this->scanner->current();
+
+            $tok = $this->scanner->next();
+            if ($tok === false) {
+                $this->parseError("Unexpected EOF in processing instruction.");
+                $this->events->processingInstruction($procName, $data);
+                return true;
+            }
+        }
+
+        $this->scanner->next(); // >
+        $this->scanner->next(); // Next token.
+        $this->events->processingInstruction($procName, $data);
+        return true;
+    }
+
+    // ================================================================
+    // UTILITY FUNCTIONS
+    // ================================================================
+
+    /**
+     * Read from the input stream until we get to the desired sequene
+     * or hit the end of the input stream.
+     */
+    protected function readUntilSequence($sequence)
+    {
+        $buffer = '';
+
+        // Optimization for reading larger blocks faster.
+        $first = substr($sequence, 0, 1);
+        while ($this->scanner->current() !== false) {
+            $buffer .= $this->scanner->charsUntil($first);
+
+            // Stop as soon as we hit the stopping condition.
+            if ($this->sequenceMatches($sequence, false)) {
+                return $buffer;
+            }
+            $buffer .= $this->scanner->current();
+            $this->scanner->next();
+        }
+
+        // If we get here, we hit the EOF.
+        $this->parseError("Unexpected EOF during text read.");
+        return $buffer;
+    }
+
+    /**
+     * Check if upcomming chars match the given sequence.
+     *
+     * This will read the stream for the $sequence. If it's
+     * found, this will return true. If not, return false.
+     * Since this unconsumes any chars it reads, the caller
+     * will still need to read the next sequence, even if
+     * this returns true.
+     *
+     * Example: $this->sequenceMatches('</script>') will
+     * see if the input stream is at the start of a
+     * '</script>' string.
+     */
+    protected function sequenceMatches($sequence, $caseSensitive = true)
+    {
+        $len = strlen($sequence);
+        $buffer = '';
+        for ($i = 0; $i < $len; ++ $i) {
+            $tok = $this->scanner->current();
+            $buffer .= $tok;
+
+            // EOF. Rewind and let the caller handle it.
+            if ($tok === false) {
+                $this->scanner->unconsume($i);
+                return false;
+            }
+            $this->scanner->next();
+        }
+
+        $this->scanner->unconsume($len);
+        return $caseSensitive ? $buffer == $sequence : strcasecmp($buffer, $sequence) === 0;
+    }
+
+    /**
+     * Send a TEXT event with the contents of the text buffer.
+     *
+     * This emits an EventHandler::text() event with the current contents of the
+     * temporary text buffer. (The buffer is used to group as much PCDATA
+     * as we can instead of emitting lots and lots of TEXT events.)
+     */
+    protected function flushBuffer()
+    {
+        if ($this->text === '') {
+            return;
+        }
+        $this->events->text($this->text);
+        $this->text = '';
+    }
+
+    /**
+     * Add text to the temporary buffer.
+     *
+     * @see flushBuffer()
+     */
+    protected function buffer($str)
+    {
+        $this->text .= $str;
+    }
+
+    /**
+     * Emit a parse error.
+     *
+     * A parse error always returns false because it never consumes any
+     * characters.
+     */
+    protected function parseError($msg)
+    {
+        $args = func_get_args();
+
+        if (count($args) > 1) {
+            array_shift($args);
+            $msg = vsprintf($msg, $args);
+        }
+
+        $line = $this->scanner->currentLine();
+        $col = $this->scanner->columnOffset();
+        $this->events->parseError($msg, $line, $col);
+        return false;
+    }
+
+    /**
+     * Decode a character reference and return the string.
+     *
+     * Returns false if the entity could not be found. If $inAttribute is set
+     * to true, a bare & will be returned as-is.
+     *
+     * @param boolean $inAttribute
+     *            Set to true if the text is inside of an attribute value.
+     *            false otherwise.
+     */
+    protected function decodeCharacterReference($inAttribute = false)
+    {
+
+        // If it fails this, it's definitely not an entity.
+        if ($this->scanner->current() != '&') {
+            return false;
+        }
+
+        // Next char after &.
+        $tok = $this->scanner->next();
+        $entity = '';
+        $start = $this->scanner->position();
+
+        if ($tok == false) {
+            return '&';
+        }
+
+        // These indicate not an entity. We return just
+        // the &.
+        if (strspn($tok, static::WHITE . "&<") == 1) {
+            // $this->scanner->next();
+            return '&';
+        }
+
+        // Numeric entity
+        if ($tok == '#') {
+            $tok = $this->scanner->next();
+
+            // Hexidecimal encoding.
+            // X[0-9a-fA-F]+;
+            // x[0-9a-fA-F]+;
+            if ($tok == 'x' || $tok == 'X') {
+                $tok = $this->scanner->next(); // Consume x
+
+                // Convert from hex code to char.
+                $hex = $this->scanner->getHex();
+                if (empty($hex)) {
+                    $this->parseError("Expected &#xHEX;, got &#x%s", $tok);
+                    // We unconsume because we don't know what parser rules might
+                    // be in effect for the remaining chars. For example. '&#>'
+                    // might result in a specific parsing rule inside of tag
+                    // contexts, while not inside of pcdata context.
+                    $this->scanner->unconsume(2);
+                    return '&';
+                }
+                $entity = CharacterReference::lookupHex($hex);
+            }             // Decimal encoding.
+            // [0-9]+;
+            else {
+                // Convert from decimal to char.
+                $numeric = $this->scanner->getNumeric();
+                if ($numeric === false) {
+                    $this->parseError("Expected &#DIGITS;, got &#%s", $tok);
+                    $this->scanner->unconsume(2);
+                    return '&';
+                }
+                $entity = CharacterReference::lookupDecimal($numeric);
+            }
+        } elseif ($tok === '=' && $inAttribute) {
+            return '&';
+        } else { // String entity.
+
+            // Attempt to consume a string up to a ';'.
+            // [a-zA-Z0-9]+;
+            $cname = $this->scanner->getAsciiAlphaNum();
+            $entity = CharacterReference::lookupName($cname);
+
+            // When no entity is found provide the name of the unmatched string
+            // and continue on as the & is not part of an entity. The & will
+            // be converted to &amp; elsewhere.
+            if ($entity == null) {
+                if (!$inAttribute || strlen($cname) === 0) {
+                    $this->parseError("No match in entity table for '%s'", $cname);
+                }
+                $this->scanner->unconsume($this->scanner->position() - $start);
+                return '&';
+            }
+        }
+
+        // The scanner has advanced the cursor for us.
+        $tok = $this->scanner->current();
+
+        // We have an entity. We're done here.
+        if ($tok == ';') {
+            $this->scanner->next();
+            return $entity;
+        }
+
+        // If in an attribute, then failing to match ; means unconsume the
+        // entire string. Otherwise, failure to match is an error.
+        if ($inAttribute) {
+            $this->scanner->unconsume($this->scanner->position() - $start);
+            return '&';
+        }
+
+        $this->parseError("Expected &ENTITY;, got &ENTITY%s (no trailing ;) ", $tok);
+        return '&' . $entity;
+    }
+}