gistfile1.php

<?php
/**
 *  Iterates over a CSV file using the first
 *  row (column names) as the array keys for
 *  each subsequent entry returned
 */
class AssociativeCsvFileIterator extends FilterIterator
{
  protected
    /**
     *  @var  array
     */
    $_keys = array(),
    
    /**
     *  @var  integer
     */
    $_count = 0;
  
  /**
   *  @param  string  $file_name  The file to read
   *  @param  string  $delimiter  The field delimiter (one character only)
   *  @param  string  $enclosure  The field enclosure character (one character only)
   *  @param  string  $escape     The field escape character (one character only)
   */
  public function __construct($file_name, $delimiter = ',', $enclosure = '"', $escape = '\\'){
    $csv = new SplFileObject($file_name);
    $csv->setFlags(SplFileObject::READ_CSV);
    $csv->setCsvControl($delimiter, $enclosure, $escape);
    $this->_keys = array_values($csv->current());
    $this->_count = count($this->_keys);
    parent::__construct(new LimitIterator($csv, 1));
  }
  
  /**
   *  @return array
   */
  public function current(){
    return array_combine(
      $this->_keys,
      parent::current()
    );
  }
  
  /**
   *  @return boolean
   */
  public function accept(){
    return $this->_count === count(parent::current());
  }
}

It doesn't implement the Countable interface, see http://www.php.net/~helly/php/ext/spl/classFilterIterator.html. Yep, http://php.net/manual/en/function.iterator-count.php is an option; good catch. :)