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<?php

/**

 * Injector that auto paragraphs text in the root node based on

 * double-spacing.

 * @todo Ensure all states are unit tested, including variations as well.

 * @todo Make a graph of the flow control for this Injector.

 */

class HTMLPurifier_Injector_AutoParagraph extends HTMLPurifier_Injector

{

    /**

     * @type string

     */

    public $name = 'AutoParagraph';

    /**

     * @type array

     */

    public $needed = array('p');

    /**

     * @return HTMLPurifier_Token_Start

     */

    private function _pStart()

    {

        $par = new HTMLPurifier_Token_Start('p');

        $par->armor['MakeWellFormed_TagClosedError'] = true;

        return $par;

    }

    /**

     * @param HTMLPurifier_Token_Text $token

     */

    public function handleText(&$token)

    {

        $text = $token->data;

        // Does the current parent allow <p> tags?

        if ($this->allowsElement('p')) {

            if (empty($this->currentNesting) || strpos($text, "\n\n") !== false) {

                // Note that we have differing behavior when dealing with text

                // in the anonymous root node, or a node inside the document.

                // If the text as a double-newline, the treatment is the same;

                // if it doesn't, see the next if-block if you're in the document.

                $i = $nesting = null;

                if (!$this->forwardUntilEndToken($i, $current, $nesting) && $token->is_whitespace) {

                    // State 1.1: ...    ^ (whitespace, then document end)

                    //               ----

                    // This is a degenerate case

                } else {

                    if (!$token->is_whitespace || $this->_isInline($current)) {

                        // State 1.2: PAR1

                        //            ----

                        // State 1.3: PAR1\n\nPAR2

                        //            ------------

                        // State 1.4: <div>PAR1\n\nPAR2 (see State 2)

                        //                 ------------

                        $token = array($this->_pStart());

                        $this->_splitText($text, $token);

                    } else {

                        // State 1.5: \n<hr />

                        //            --

                    }

                }

            } else {

                // State 2:   <div>PAR1... (similar to 1.4)

                //                 ----

                // We're in an element that allows paragraph tags, but we're not

                // sure if we're going to need them.

                if ($this->_pLookAhead()) {

                    // State 2.1: <div>PAR1<b>PAR1\n\nPAR2

                    //                 ----

                    // Note: This will always be the first child, since any

                    // previous inline element would have triggered this very

                    // same routine, and found the double newline. One possible

                    // exception would be a comment.

                    $token = array($this->_pStart(), $token);

                } else {

                    // State 2.2.1: <div>PAR1<div>

                    //                   ----

                    // State 2.2.2: <div>PAR1<b>PAR1</b></div>

                    //                   ----

                }

            }

            // Is the current parent a <p> tag?

        } elseif (!empty($this->currentNesting) &&

            $this->currentNesting[count($this->currentNesting) - 1]->name == 'p') {

            // State 3.1: ...<p>PAR1

            //                  ----

            // State 3.2: ...<p>PAR1\n\nPAR2

            //                  ------------

            $token = array();

            $this->_splitText($text, $token);

            // Abort!

        } else {

            // State 4.1: ...<b>PAR1

            //                  ----

            // State 4.2: ...<b>PAR1\n\nPAR2

            //                  ------------

        }

    }

    /**

     * @param HTMLPurifier_Token $token

     */

    public function handleElement(&$token)

    {

        // We don't have to check if we're already in a <p> tag for block

        // tokens, because the tag would have been autoclosed by MakeWellFormed.

        if ($this->allowsElement('p')) {

            if (!empty($this->currentNesting)) {

                if ($this->_isInline($token)) {

                    // State 1: <div>...<b>

                    //                  ---

                    // Check if this token is adjacent to the parent token

                    // (seek backwards until token isn't whitespace)

                    $i = null;

                    $this->backward($i, $prev);

                    if (!$prev instanceof HTMLPurifier_Token_Start) {

                        // Token wasn't adjacent

                        if ($prev instanceof HTMLPurifier_Token_Text &&

                            substr($prev->data, -2) === "\n\n"

                        ) {

                            // State 1.1.4: <div><p>PAR1</p>\n\n<b>

                            //                                  ---

                            // Quite frankly, this should be handled by splitText

                            $token = array($this->_pStart(), $token);

                        } else {

                            // State 1.1.1: <div><p>PAR1</p><b>

                            //                              ---

                            // State 1.1.2: <div><br /><b>

                            //                         ---

                            // State 1.1.3: <div>PAR<b>

                            //                      ---

                        }

                    } else {

                        // State 1.2.1: <div><b>

                        //                   ---

                        // Lookahead to see if <p> is needed.

                        if ($this->_pLookAhead()) {

                            // State 1.3.1: <div><b>PAR1\n\nPAR2

                            //                   ---

                            $token = array($this->_pStart(), $token);

                        } else {

                            // State 1.3.2: <div><b>PAR1</b></div>

                            //                   ---

                            // State 1.3.3: <div><b>PAR1</b><div></div>\n\n</div>

                            //                   ---

                        }

                    }

                } else {

                    // State 2.3: ...<div>

                    //               -----

                }

            } else {

                if ($this->_isInline($token)) {

                    // State 3.1: <b>

                    //            ---

                    // This is where the {p} tag is inserted, not reflected in

                    // inputTokens yet, however.

                    $token = array($this->_pStart(), $token);

                } else {

                    // State 3.2: <div>

                    //            -----

                }

                $i = null;

                if ($this->backward($i, $prev)) {

                    if (!$prev instanceof HTMLPurifier_Token_Text) {

                        // State 3.1.1: ...</p>{p}<b>

                        //                        ---

                        // State 3.2.1: ...</p><div>

                        //                     -----

                        if (!is_array($token)) {

                            $token = array($token);

                        }

                        array_unshift($token, new HTMLPurifier_Token_Text("\n\n"));

                    } else {

                        // State 3.1.2: ...</p>\n\n{p}<b>

                        //                            ---

                        // State 3.2.2: ...</p>\n\n<div>

                        //                         -----

                        // Note: PAR<ELEM> cannot occur because PAR would have been

                        // wrapped in <p> tags.

                    }

                }

            }

        } else {

            // State 2.2: <ul><li>

            //                ----

            // State 2.4: <p><b>

            //               ---

        }

    }

    /**

     * Splits up a text in paragraph tokens and appends them

     * to the result stream that will replace the original

     * @param string $data String text data that will be processed

     *    into paragraphs

     * @param HTMLPurifier_Token[] $result Reference to array of tokens that the

     *    tags will be appended onto

     */

    private function _splitText($data, &$result)

    {

        $raw_paragraphs = explode("\n\n", $data);

        $paragraphs = array(); // without empty paragraphs

        $needs_start = false;

        $needs_end = false;

        $c = count($raw_paragraphs);

        if ($c == 1) {

            // There were no double-newlines, abort quickly. In theory this

            // should never happen.

            $result[] = new HTMLPurifier_Token_Text($data);

            return;

        }

        for ($i = 0; $i < $c; $i++) {

            $par = $raw_paragraphs[$i];

            if (trim($par) !== '') {

                $paragraphs[] = $par;

            } else {

                if ($i == 0) {

                    // Double newline at the front

                    if (empty($result)) {

                        // The empty result indicates that the AutoParagraph

                        // injector did not add any start paragraph tokens.

                        // This means that we have been in a paragraph for

                        // a while, and the newline means we should start a new one.

                        $result[] = new HTMLPurifier_Token_End('p');

                        $result[] = new HTMLPurifier_Token_Text("\n\n");

                        // However, the start token should only be added if

                        // there is more processing to be done (i.e. there are

                        // real paragraphs in here). If there are none, the

                        // next start paragraph tag will be handled by the

                        // next call to the injector

                        $needs_start = true;

                    } else {

                        // We just started a new paragraph!

                        // Reinstate a double-newline for presentation's sake, since

                        // it was in the source code.

                        array_unshift($result, new HTMLPurifier_Token_Text("\n\n"));

                    }

                } elseif ($i + 1 == $c) {

                    // Double newline at the end

                    // There should be a trailing </p> when we're finally done.

                    $needs_end = true;

                }

            }

        }

        // Check if this was just a giant blob of whitespace. Move this earlier,

        // perhaps?

        if (empty($paragraphs)) {

            return;

        }

        // Add the start tag indicated by \n\n at the beginning of $data

        if ($needs_start) {

            $result[] = $this->_pStart();

        }

        // Append the paragraphs onto the result

        foreach ($paragraphs as $par) {

            $result[] = new HTMLPurifier_Token_Text($par);

            $result[] = new HTMLPurifier_Token_End('p');

            $result[] = new HTMLPurifier_Token_Text("\n\n");

            $result[] = $this->_pStart();

        }

        // Remove trailing start token; Injector will handle this later if

        // it was indeed needed. This prevents from needing to do a lookahead,

        // at the cost of a lookbehind later.

        array_pop($result);

        // If there is no need for an end tag, remove all of it and let

        // MakeWellFormed close it later.

        if (!$needs_end) {

            array_pop($result); // removes \n\n

            array_pop($result); // removes </p>

        }

    }

    /**

     * Returns true if passed token is inline (and, ergo, allowed in

     * paragraph tags)

     * @param HTMLPurifier_Token $token

     * @return bool

     */

    private function _isInline($token)

    {

        return isset($this->htmlDefinition->info['p']->child->elements[$token->name]);

    }

    /**

     * Looks ahead in the token list and determines whether or not we need

     * to insert a <p> tag.

     * @return bool

     */

    private function _pLookAhead()

    {

        if ($this->currentToken instanceof HTMLPurifier_Token_Start) {

            $nesting = 1;

        } else {

            $nesting = 0;

        }

        $ok = false;

        $i = null;

        while ($this->forwardUntilEndToken($i, $current, $nesting)) {

            $result = $this->_checkNeedsP($current);

            if ($result !== null) {

                $ok = $result;

                break;

            }

        }

        return $ok;

    }

    /**

     * Determines if a particular token requires an earlier inline token

     * to get a paragraph. This should be used with _forwardUntilEndToken

     * @param HTMLPurifier_Token $current

     * @return bool

     */

    private function _checkNeedsP($current)

    {

        if ($current instanceof HTMLPurifier_Token_Start) {

            if (!$this->_isInline($current)) {

                // <div>PAR1<div>

                //      ----

                // Terminate early, since we hit a block element

                return false;

            }

        } elseif ($current instanceof HTMLPurifier_Token_Text) {

            if (strpos($current->data, "\n\n") !== false) {

                // <div>PAR1<b>PAR1\n\nPAR2

                //      ----

                return true;

            } else {

                // <div>PAR1<b>PAR1...

                //      ----

            }

        }

        return null;

    }

}

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