Schema::findTables

public Schema::findTables($table_expression)

public function findTables($table_expression) {
  // Load all the tables up front in order to take into account per-table
  // prefixes. The actual matching is done at the bottom of the method.
  $condition = $this->buildTableNameCondition('%', 'LIKE');
  $condition->compile($this->connection, $this);

  $individually_prefixed_tables = $this->connection->getUnprefixedTablesMap();
  $default_prefix = $this->connection->tablePrefix();
  $default_prefix_length = strlen($default_prefix);
  $tables = [];
  // Normally, we would heartily discourage the use of string
  // concatenation for conditionals like this however, we
  // couldn't use db_select() here because it would prefix
  // information_schema.tables and the query would fail.
  // Don't use {} around information_schema.tables table.
  $results = $this->connection->query("SELECT table_name FROM information_schema.tables WHERE " . (string) $condition, $condition->arguments());
  foreach ($results as $table) {
    // Take into account tables that have an individual prefix.
    if (isset($individually_prefixed_tables[$table->table_name])) {
      $prefix_length = strlen($this->connection->tablePrefix($individually_prefixed_tables[$table->table_name]));
    }
    elseif ($default_prefix && substr($table->table_name, 0, $default_prefix_length) !== $default_prefix) {
      // This table name does not start the default prefix, which means that
      // it is not managed by Drupal so it should be excluded from the result.
      continue;
    }
    else {
      $prefix_length = $default_prefix_length;
    }

    // Remove the prefix from the returned tables.
    $unprefixed_table_name = substr($table->table_name, $prefix_length);

    // The pattern can match a table which is the same as the prefix. That
    // will become an empty string when we remove the prefix, which will
    // probably surprise the caller, besides not being a prefixed table. So
    // remove it.
    if (!empty($unprefixed_table_name)) {
      $tables[$unprefixed_table_name] = $unprefixed_table_name;
    }
  }

  // Convert the table expression from its SQL LIKE syntax to a regular
  // expression and escape the delimiter that will be used for matching.
  $table_expression = str_replace(array('%', '_'), array('.*?', '.'), preg_quote($table_expression, '/'));
  $tables = preg_grep('/^' . $table_expression . '$/i', $tables);

  return $tables;
}