<?php
/**
* String replacment class
* Could be used in a translation system
*
* Could eventually be extended to make a fully featured template parser.
*
* TODO: Add support for : in extra parameter - FIXED
* TODO: Add support for {IF} inside {FOREACH} 
* TODO: Improve parsing routine
* TODO: Document better
* 
* String format
* Replace tag with simple variable
* 'Test 1: {$var}'
* Replace tag with object of variable (Only one level supported)
* 'Test 2: {$var->object}'
* Replace tag with array element (Only one level supported)
* 'Test 3:{$var[object]}'
* Replace tag with result from function where varibale is parsed as first parameter
* 'Test 4: {$var:strlen}' 		This will replace the tag with the content from strlen function. (Any function can be used, but not methods)
* Replace tag with result from function using extra parameter
* 'Test 5: {$var:date:d-m-y}' 	This will replace tag with content from the date function using 'd-m-y' as the first parameter and value of var as second.
* Escaping tag replacment
* 'Test 6: {$this text is in braces}  will be removed using the final parser the removes unreplaced tags. only matching braces will be removed not single } or {.
* Condition 
* 'Test 7: {IF $var}Show this text i $var is true{/IF}  This tag is very usefull if you would like to display some content if the variable is true.  You can use the ! in front of $ to invert the conditional. Empty string are determined false
* Loop
* Test 8: {FOREACH $var}Loop thought an array {$var}{/FOREACH} This tags loop througt a entire array. (You still acceses the variables using the same keyword)  
* NOTE:  IF statements inside FOREACH statements is currently not allowed. This will be fixed in later version.
*/

class Parser {
var $org_string;
var $output;
var $replacement;
var $patterns;
var $replacefunc;

	function Parser() {
		//Assign Patterns for replacement
		$this->patterns = array(
			//IF call
			'/{IF (!?)\$([a-zA-Z0-9]+\.?[a-zA-Z0-9]*)}([\w\W]+){\/IF}/',
			//Foreach call
			'/{FOREACH \$([a-zA-Z0-9]+\.?[a-zA-Z0-9]*)}([\w\W]+){\/FOREACH}/',
			//Simple variable replacement
	        '/{\$([a-zA-Z0-9]+\.?[a-zA-Z0-9]*)}/', 
			//Simple replacment of variable or subvariable (Calling userfunc before output)
			'/{\$([a-zA-Z0-9]+\.?[a-zA-Z0-9_]*):([a-zA-Z0-9_]+)}/',
			//Replacement of variable using callback function with extra parameter
			'/{\$([a-zA-Z0-9]+\.?[a-zA-Z0-9]*):([a-zA-Z0-9_]+):([a-zA-Z0-9_%-: ]+)}/'

		);
			
		$this->replacefunc = array(
			//IF callback
			array('self','replace_if'),
			//Foreach callback
			array('self','replace_foreach'),
			//Simple variable replacement
	        array('self','replace_var'), 
			//Simple replacment of variable or subvariable (Calling userfunc before output)
			array('self','replace_function'),
			//Replacement of variable using callback function with extra parameter		
			array('self','replace_function_para')

		);
			
			
	}

	function string($string) {
		$this->org_string = $string;
		$this->output = $string;
	}

	function add($tag,$value) {
		if(is_object($value)) { $value = get_object_vars($value); }
		$this->replacement[$tag] = $value;
	}
	function batchadd($array) {
		foreach($array as $key=>$value) {
			$this->add($key,$value);
		}
	}

	function render() {
		$this->output = $this->parse($this->output);
		return $this->output;
	}
		
	private function parse($string) {
		for($t=0;$t<count($this->patterns);$t++) {
			$string = preg_replace_callback($this->patterns[$t], $this->replacefunc[$t], $string);
		}
		return $string;
	}
		//Thsi is a private function which stips all remaing '{' and '}' tags. This way unreplaced tags won't be displayed.
	private function striptags($string) {
		return preg_replace('/{[a-zA-Z0-9:_\$]*}/','',$string);
	}

	function var_value($string) {
		$parsed = explode('.',$string);
		if($parsed[1]) { return $this->replacement[$parsed[0]][$parsed[1]]; }
		return $this->replacement[$parsed[0]];
	}

	function unset_var_value($string) {
		$parsed = explode('.',$string);
		if($parsed[1]) { unset($this->replacement[$parsed[0]][$parsed[1]]); }
		unset($this->replacement[$parsed[0]]);
	}

	
	function replace_var($callback) {
		return $this->var_value($callback[1]);
	}
	

	
	function replace_function($callback) {
		return call_user_func($callback[2],$this->var_value($callback[1]));
	}

	function replace_function_para($callback) {
		return call_user_func($callback[2],$callback[3],$this->var_value($callback[1]));
	}

	function replace_if($callback) {
			if($callback[1]=='') {if($this->var_value($callback[2])) {return $this->parse($callback[3]); }}
			if($callback[1]=='!') {if(!$this->var_value($callback[2])) {return $this->parse($callback[3]); }}
		return '';
	}

	function replace_foreach($callback) {
		$temp = $this->var_value($callback[1]);
		$this->unset_var_value($callback[1]);
		$parsed = explode('.',$callback[1]);
		foreach($temp as $var) {
				if($parsed[1]) { 
					$this->replacement[$parsed[0]][$parsed[1]] = $var; 
				} else { 
					$this->replacement[$parsed[0]] = $var;
				}
var_dump($this->replacement);
			$string .= $this->parse($callback[2]);
		}
	return $string; 
	}
		
}
?>