<?php

abstract class Expression {
	
	static protected $types = array();
	
	public static function getParserExtension () {
		
		$context = get_called_class();
		
		return function ( &$parseState, $token, $nodes ) use ( $context ) {
			
			return $context::parse($parseState, $token, $nodes);
			
		};
		
	}
	
	public static function dispatch ( $type, $action ) {
		
		//~ echo get_called_class(), "\n";
		
		if ( !empty(static::$types[$type][$action]) )
			return static::$types[$type][$action]['value'];
		
		$class = get_called_class() . 'Type' . ucfirst($type);
		$delegate = get_called_class() . ucfirst($action);
		
		$method = $action . ucfirst($type);
		
		if ( class_exists($class) )
			$caller = array(
				$class,
				$action
			);
			
		elseif ( class_exists($delegate) && method_exists($delegate, $method) )
			$caller = array(
				$delegate,
				$method
			);
			
		elseif ( get_called_class() !== __CLASS__ )
			$caller = call_user_func(
				array(get_parent_class(get_called_class()), 'dispatch'),
				$type,
				$action
			);
		
		else $caller = null;
		
		return static::$types[$type][$action]['value'] = $caller;
		
	}
	
	public static function build ( $type ) {
		
		$args = func_get_args();
		array_shift($args);
		
		if ( $func = static::dispatch($type, __FUNCTION__) )
			return call_user_func_array(
				$func,
				$args
			);
		
		else throw static::buildException($type, __FUNCTION__);
		
	}
	
	public static function parse ( &$parseState, $token, $nodes ) {
		
		if ( $func = static::dispatch($token['type'], __FUNCTION__) )
			return call_user_func(
				$func,
				$parseState,
				$token,
				$nodes
			);
		
		else return $nodes;
		
	}
	
	public static function serialize ( $ast ) {
		
		if ( $func = static::dispatch($ast['type'], __FUNCTION__) )
			return call_user_func(
				$func,
				get_called_class(),
				$ast
			);
		
		else throw static::buildException($type, __FUNCTION__);
		
	}
	
	public static function compile ( $ast ) {
		
		if ( $func = static::dispatch($ast['type'], __FUNCTION__) )
			return call_user_func(
				$func,
				get_called_class(),
				$ast
			);
		
		else throw static::buildException($ast['type'], __FUNCTION__);
		
	}
	
	public static function run ( $ast ) {
		
		if ( $func = static::dispatch($ast['type'], __FUNCTION__) )
			return call_user_func(
				$func,
				get_called_class(),
				$ast
			);
		
		else throw static::buildException($type, __FUNCTION__);
		
	}
	
	public static function fromData ( $data ) {
		
		if ( is_array($data) ) {
			
			$elements = array();
			foreach ( $data as $k => $v )
				$elements[] = array(
					static::fromData($k),
					static::fromData($v)
				);
			
			return static::build($elements);
			
		} elseif ( is_float($data) )
			return static::buildFloat($data);
		
		elseif ( is_numeric($data) )
			return static::buildInteger($data);
		
		elseif ( is_bool($data) )
			return $data ? static::buildTrue() : static::buildFalse();
		
		elseif ( is_null($data) )
			return static::buildNull();
		
		elseif ( is_string($data) )
			$code = "'" . implode('\' +. "\n" +. \'', explode("\n", addslashes($data))) . "'";
		
		else throw new Exception('Object cannot be build from data : ' . get_class($data));
		
	}
	
	public static function buildException ( $type, $action ) {
		
		return new Exception(sprintf(
			'%1$s error : type "%2$s" has no action "%3$s" !',
			get_called_class(),
			$type,
			$action
		));
		
	}
	
}

?>