<?php
/**
 * Harmony
 * Copyright (c) 2008 Maxime Bouroumeau-Fuseau
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @category Harmony
 * @package Harmony_Parser 
 * @author Maxime Bouroumeau-Fuseau
 * @copyright 2008 (c) Maxime Bouroumeau-Fuseau
 * @license http://www.opensource.org/licenses/mit-license.php
 * @link http://www.harmony-framework.com
 */
 
/** Harmony_Parser_Context */
require_once 'Harmony/Parser/Context.php';

/**
 * Linear Parser
 * 
 * @category Harmony
 * @package Harmony_Parser 
 * @copyright 2008 (c) Maxime Bouroumeau-Fuseau
 * @license http://www.opensource.org/licenses/mit-license.php
 */
abstract class Harmony_Parser_Abstract
{
	/**
	 * End of file token
	 */
	const EOF = 'Eof';
	
	/**
	 * Paths where to find contexts
	 *
	 * @var array
	 */
	protected $_contextPaths = array();
	
	/**
	 * Tokens
	 *
	 * @var array
	 */
	protected $_tokens = array();
	
	/**
	 * Data to parse
	 *
	 * @var mixed
	 */
	protected $_data;
	
	/**
	 * Adds a new path where to search for context class
	 *
	 * @param string $path
	 * @param string $prefix OPTIONAL Class prefix
	 */
	public function addContextPath($path, $prefix = '')
	{
		$this->_contextPaths[$path] = $prefix;
	}
	
	/**
	 * Loads a context class and returns its name
	 *
	 * @param string $context
	 * @return string
	 */
	public function getContextClassName($context)
	{
		foreach ($this->_contextPaths as $path => $prefix) {
			$filename = rtrim($path, DIRECTORY_SEPARATOR) 
					  . DIRECTORY_SEPARATOR . $context . '.php';
			/* checks if the context file exists in the current directory */
			if (file_exists($filename)) {
				require_once $filename;
				$classname = $prefix . $context;
				
				/* checks if the context class inherits from Harmony_Parser_Context */
				if (!in_array('Harmony_Parser_Context', class_parents($classname))) {
					require_once 'Harmony/Parser/Exception.php';
					throw new Harmony_Parser_Exception('Context must inherit from Harmony_Parser_Context');
				}
				
				return $classname;
			}
		}
		
		require_once 'Harmony/Parser/Exception.php';
		throw new Harmony_Parser_Exception('Context not found: '. $context);
	}
	
	/**
	 * Sets a token
	 *
	 * @param string $name
	 * @param string $regexp
	 */
	public function setToken($name, $regexp)
	{
		$this->_tokens[$name] = $regexp;
	}
	
	/**
	 * Removes a token
	 *
	 * @param string $name
	 */
	public function removeToken($name)
	{
		if (!array_key_exists($name, $this->_tokens)) {
			require_once 'Harmony/Parser/Exception.php';
			throw new Harmony_Parser_Exception('Token ' . $name . ' does not exists');
		}
		unset($this->_tokens[$name]);
	}
	
	/**
	 * Removes all tokens
	 */
	public function clearTokens()
	{
		$this->_tokens = array();
	}
	
	/**
	 * Gets all tokens
	 *
	 * @return array
	 */
	public function getTokens()
	{
		return $this->_tokens;
	}
	
	/**
	 * Sets the data to parse
	 *
	 * @param mixed $data
	 */
	public function setData($data)
	{
		$this->_data = $data;
	}
	
	/**
	 * Gets the data to parse
	 *
	 * @return mixed
	 */
	public function getData()
	{
		return $this->_data;
	}
	
	/**
	 * Enters a next context
	 *
	 * @param string $context
	 * @param array $params OPTIONAL Context parameters
	 * @return mixed Data returned by context
	 */
	public abstract function enterContext($context, $params = array());
}