Generic data object with alias sync

AliasSyncDataObject.php

<?php
/**
 * AliasSyncDataObject
 * This is a data object that allows models to be marshaled from Doctrine to Si
 * and back again.
 * It is mostly just coordinating field alias names and keeping their values in sync.
 */
 
class AliasSyncDataObject {

	private $doctrine_record_name = null;

	// array(Doctrine_name => Si_name, ...)
	private $attribute_alias_mappings = array();

	private $attribute_names = array();
	private $attribute_alias_names = array();
	
	// array('attribute1_name' => value, ...)
	private $attribute_value_map = array();

	public function __construct(Doctrine_record $doctrine_record)
	{
		$this->doctrine_record_name = get_class($doctrine_record);
		$this->attribute_value_map = $doctrine_record->toArray();
		$this->attribute_names = array_keys($this->attribute_value_map);
		$this->attribute_alias_mappings = $doctrine_record->si_field_alias_mappings();
		$this->attribute_alias_names = array_values($this->attribute_alias_mappings);
	}

	public function __get($attribute_name)
	{
		$this->verify_attribute_exists($attribute_name);
		return $this->attribute_value_map[$this->get_attribute_name($attribute_name)];

	}
	public function __set($attribute_name, $value)
	{
		$this->verify_attribute_exists($attribute_name);
		$this->set_attribute($this->get_attribute_and_alias($attribute_name), $value);
	}
	public function add_attribute($attribute_name, $attribute_value)
	{
		$this->attribute_value_map[$attribute_name] = $attribute_value;
		array_push($this->attribute_names, $attribute_name);
	}

	/**
	 * Sets the value provided to this attribute.  Also takes aliasses into account.
	 * If one exists, it assures that the attribute and its aliases values are kept in sync .
	 *
	 * @param array $attribute_and_alias_names Not all attributes have aliases so it is
	 * possible that there is no alias and this is just an array with the attribute name only.
	 * @param  $value
	 * @return void
	 */
	private function set_attribute(array $attribute_and_alias_names, $value)
	{
		foreach($attribute_and_alias_names as $name )
		{
			$this->attribute_value_map[$name]=$value;
		}
	}
	/**
	 * @throws InvalidArgumentException
	 * @param  $attribute_name
	 * @return string
	 */
	private function verify_attribute_exists($attribute_name)
	{
		if( ! $this->is_an_attribute($attribute_name)
		    &&
		    ! $this->is_an_attribute_alias($attribute_name))
		{
			throw new InvalidArgumentException("Proxy Model {$this->doctrine_record_name}"
				." does NOT have attribute {$attribute_name} defined");
		}
	}
	private function get_attribute_and_alias($attribute_name)
	{
		$attribute_and_alias = array($attribute_name);
		if($this->is_an_attribute_alias($attribute_name))
		{
			$attribute_and_alias[] = $this->attribute_name_for_alias($attribute_name);
		}
		else if($this->attribute_has_an_alias($attribute_name))
		{
			$attribute_and_alias[] = $this->alias_name_for_attribute($attribute_name);
		}
		return $attribute_and_alias;
	}
	private function get_attribute_name($name)
	{
		if($this->is_an_attribute_alias($name))
		{
			return $this->attribute_name_for_alias($name);
		}
		return $name;
	}
	private function is_an_attribute_alias($attribute_name)
	{
		return in_array($attribute_name, $this->attribute_alias_names);
	}
	private function attribute_has_an_alias($attribute_name)
	{
		return array_key_exists($attribute_name, $this->attribute_alias_mappings);
	}
	private function is_an_attribute($attribute_name)
	{
		return in_array($attribute_name, $this->attribute_names);
	}
	private function attribute_name_for_alias($alias_name)
	{
		return array_search($alias_name, $this->attribute_alias_mappings);
	}
	private function alias_name_for_attribute($attribute_name)
	{
		return $this->attribute_alias_mappings[$attribute_name];
	}

}