RegexCounter.php in Bibliography Module 7.2

Namespace

Nametools

File

lib/msrc-authortool/src/Nametools/RegexCounter.php

<?php

namespace Nametools;


/**
 * Regexcounter is a class that counts the expected
 * number of matches for a given REGEX pattern
 *
 * It was ported entirely from:
 * @link http://noteslog.com/post/how-to-count-expected-matches-of-a-php-regular-expression/
 */
class RegexCounter {

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

  /**
   * Returns how many groups (non-named) there are in the given pattern
   *
   * Ignores namesGroups and numberedGroups for simplicity
   *
   * @param string $pattern
   * @return int
   */
  public function count($pattern) {
    return $this
      ->countGroups($pattern, $null, $null);
  }

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

  /**
   * Returns how many groups (numbered or named) there are in the given $pattern
   *
   * @param string $pattern
   * @param array  $namedGroups
   * @param array  $numberedGroups
   * @return int
   */
  public function countGroups($pattern, &$namedGroups, &$numberedGroups) {
    $result = $this
      ->countGroupsIgnoreHellternations($pattern, $namedGroups, $numberedGroups);
    $hellternations = $this
      ->findHellternations($pattern);
    if (empty($hellternations)) {
      return $result;
    }
    foreach ($hellternations as $hellternation) {
      $count = array();
      $pieces = $this
        ->explodeAlternation($hellternation);
      foreach ($pieces as $piece) {
        $count[] = $this
          ->countGroups($piece, $dummy, $dummy);
      }
      $max = max($count);
      $easy = $this
        ->countGroupsIgnoreHellternations($hellternation, $dummy, $dummy);
      $result = $result - $easy + $max;
    }
    return $result;
  }

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

  /**
   * Returns how many groups (numbered or named) there are in the given $pattern,
   * ignoring hellternations (?|...|...)
   *
   * @param string $pattern
   * @param array  $namedGroups
   * @param array  $numberedGroups
   *
   * @return integer
   */
  function countGroupsIgnoreHellternations(&$pattern, &$namedGroups, &$numberedGroups) {
    $findExplicitelyEscaped = '/\\\\./';
    $pattern = preg_replace($findExplicitelyEscaped, '%', $pattern);
    $findImplicitelyEscaped = '/\\[[^\\]]*\\]/';
    $pattern = preg_replace($findImplicitelyEscaped, '%', $pattern);
    $findNumberedGroups = '/\\((?!\\?)/';
    $numberedGroups_count = preg_match_all($findNumberedGroups, $pattern, $numberedGroups, PREG_SET_ORDER | PREG_OFFSET_CAPTURE);
    $findConditions = '/\\(\\?\\(/';
    $conditions_count = preg_match_all($findConditions, $pattern, $dummy);
    $numberedGroups_count -= $conditions_count;
    $find_namedGroups = '/\\(\\?P?(?:(?:<([^>]+)>)|(?:\'([^\']+)\'))/';
    $namedGroups_count = preg_match_all($find_namedGroups, $pattern, $namedGroups, PREG_SET_ORDER | PREG_OFFSET_CAPTURE);
    $numberedGroups_count += $namedGroups_count;

    //named groups also add as many numbered groups
    $dupnames = array();
    foreach ($namedGroups as $named_group) {
      $name = $named_group[1][0];
      if (isset($dupnames[$name])) {
        $dupnames[$name] += 1;
      }
      else {
        $dupnames[$name] = 0;
      }
    }
    $dupnames_count = array_sum($dupnames);
    $namedGroups_count -= $dupnames_count;

    //duplicate names are added only once
    $result = $numberedGroups_count + $namedGroups_count;
    return $result;
  }

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

  /**
   * Returns the hellternations which are siblings to each other.
   * NOTE: the given $pattern is assumed to not contain escaped parentheses.
   *
   * @param string $pattern a string of alternations wrapped into (?|...)
   * @return array
   * @throws RegexCounterException
   */
  protected function findHellternations($pattern) {
    $result = array();
    $token = '(?|';
    $tokenLen = strlen($token);
    $offset = 0;
    do {
      $start = strpos($pattern, $token, $offset);
      if (FALSE === $start) {
        return $result;
      }
      $open = 1;
      $start += $tokenLen;
      for ($i = $start, $iTop = strlen($pattern); $i < $iTop; $i++) {

        //$current = $pattern[$i];
        if ($pattern[$i] == '(') {
          $open += 1;
        }
        elseif ($pattern[$i] == ')') {
          $open -= 1;
          if (0 == $open) {
            $result[$start] = substr($pattern, $start, $i - $start);
            $offset = $i + 1;
            break;
          }
        }
      }
    } while ($i < $iTop);
    if (0 != $open) {
      throw new RegexCounterException('Unbalanced parentheses.');
    }
    return $result;
  }

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

  /**
   * Explodes an alternation on outer pipes.
   * NOTE: the given $pattern is assumed to not contain escaped parentheses nor escaped pipes.
   *
   * @param string $pattern a string with balanced (possibly nested) parentheses and pipes
   * @return array
   * @throws RegexCounterException
   */
  protected function explodeAlternation($pattern) {
    $result = array();
    $token = '|';
    $open = 0;
    $start = 0;
    for ($i = $start, $iTop = strlen($pattern); $i < $iTop; $i++) {

      //$current = $pattern[$i];
      if ($pattern[$i] == '(') {
        $open += 1;
      }
      elseif ($pattern[$i] == ')') {
        $open -= 1;
      }
      elseif ($pattern[$i] == '|') {
        if (0 == $open) {
          $result[$start] = substr($pattern, $start, $i - $start);
          $start = $i + 1;
        }
      }
    }
    $result[$start] = substr($pattern, $start);
    if (0 != $open) {
      throw new RegexCounterException('Unbalanced parentheses.');
    }
    return $result;
  }

}

/* EOF: RegexCounter.php */

Classes

Name	Description
RegexCounter	Regexcounter is a class that counts the expected number of matches for a given REGEX pattern