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trait TreeEncodeTrait in Extensible BBCode 8.3

Same name and namespace in other branches
  1. 4.0.x standard/src/TreeEncodeTrait.php \Drupal\xbbcode_standard\TreeEncodeTrait

Static helper functions for tag plugins that parse their top-level text.

Tags which parse their own content (eg [list] and [table]) are hindered by tags nested inside them. If they parsed the rendered output, they'd need to take responsibility for markup integrity. If they used the source, they'd need to re-run the whole parser on it.

Instead, these helpers will reversibly "flatten" a parse tree, concatenating top-level text elements and replacing nested tags with placeholder values.

Hierarchy

2 files declare their use of TreeEncodeTrait
ListTagPlugin.php in standard/src/Plugin/XBBCode/ListTagPlugin.php
TableTagPlugin.php in standard/src/Plugin/XBBCode/TableTagPlugin.php

File

standard/src/TreeEncodeTrait.php, line 20

Namespace

Drupal\xbbcode_standard
View source
trait TreeEncodeTrait {

  /**
   * Concatenate the top-level text of the tree.
   *
   * The text elements are concatenated, inserting placeholders for each tag
   * element contained in the children.
   *
   * @param array $children
   *   A sequence of elements representing the children of a single element.
   *
   * @return string[]
   *   An array with two values:
   *   - A unique delimiter token.
   *   - A concatenated string, in which the i-th tag element is replaced with
   *     a placeholder string "{token:i}", and text elements are left in place.
   */
  protected static function encodeTree(array $children) : array {
    $output = [];
    foreach ($children as $i => $child) {
      if ($child instanceof TextElement) {
        $output[] = $child
          ->getText();
      }
      else {
        $output[] = $i;
      }
    }
    $text = implode('', $output);
    $token = 100000;
    while (strpos($text, (string) $token) !== FALSE) {
      $token++;
    }
    foreach ($output as $i => $item) {
      if (is_int($item)) {
        $output[$i] = "{tag:{$token}:{$item}}";
      }
    }
    return [
      $token,
      implode('', $output),
    ];
  }

  /**
   * Decode a part of the encoded tree.
   *
   * @param string $cell
   *   The text (or part of the text) of the encoded tree.
   * @param array $children
   *   The children which were previously encoded.
   * @param string $token
   *   The token used as a placeholder.
   *
   * @return \Drupal\xbbcode\Parser\Tree\TagElement
   *   A pseudo-tag element (empty name) containing the part of the tree
   *   represented by $cell.
   */
  protected static function decodeTree($cell, array $children, $token) : TagElement {
    $items = preg_split("/{tag:{$token}:(\\d+)}/", $cell, NULL, PREG_SPLIT_DELIM_CAPTURE);
    $tree = new TagElement('', '', '');
    foreach ($items as $i => $item) {
      if ($item !== '') {
        $tree
          ->append($i % 2 ? $children[$item] : new TextElement($item));
      }
    }
    return $tree;
  }

}

Members

Namesort descending Modifiers Type Description Overrides
TreeEncodeTrait::decodeTree protected static function Decode a part of the encoded tree.
TreeEncodeTrait::encodeTree protected static function Concatenate the top-level text of the tree.