[RESOLVED] ini parser class with filters

[cgraz]

I'm in the process of creating a flexible INI parser class that I can use for a project and in the future. I need the ability to add filters easily.

I went through several versions of this INI parser, and in the middle of using it, I realized it wasn't as flexible as I had thought. What I'd like are some suggestions on how to create an advanced filtering method in my class. Here's what I'd like to do:

use parse_ini_file() to initially parse the file. Most likely will be using sections, but need the ability parse w/out sections.

Filters:
I want to create functions that perform a filter, for example, I might have a function called replace_backticks_with_quotes that looks like this:

function replace_backticks_with_quotes( $value )
{
     return str_replace('`', '"', $value);
}

To use the filters, I'd like to call them before I run the parser, so that when I actually parse, it returns the parsed file with all the filters already executed add_filter('replace_backticks_with_quotes')

The problem with this is I'd like some advanced functionality on my filter. I'd like to be able to filter values only if their attributes meet certain requirements. For example, I might want to pass my add_filter function an array of keys, and the filter will only affect those values that have those keys in the ini file.

So my ini file might have a part that looks like this:

special 1 = validate, Your input did not validate
special 2 = check, Your input did not check out
regular = this is the value

And I could say something like

add_filter('explode_commas', array('special 1', 'special 2'))

And it would run the function explode_commas that might look something like this

function explode_commas( $value )
{
	return explode(",", $value, 2);
}

But what if I want to perform a regular expression to see if a key meets certain criteria like so

'/^(special|test|rule|etc)(\s)?([0-9a-zA-Z_-]{1,})?$/'

Or what if I want to perform a regexp on a value before I filter it. I was initially running my constructor function like this:

	function parse( $file, $sections = true )
	{
		// Parse INI File into array
		$contents = @parse_ini_file( $file, $sections );

	// Run Filters
	if (strtolower (get_class ($this)) == 'ini') {
		$contents = $this->filter ($contents, $sections);
	}

	$this->contents = $contents;
	return $contents;
}

and filter() would loop through $this->contents and execute all the filters ($this->_filters)

Usage Example:

$ini = new INI;

$ini->add_filter('explode_commas');
$ini->add_filter('replace_backticks_with_quotes');
$settings = $ini->ini_parse( $file );
$ini->clear_filters();

I don't need someone to write this for me, just some help with the logic as I'm completely stuck.

[cgraz]

Resolved. I created an add_filter function that looks like this:

	function add_filter( $func, $keys = array(), $type = false, $extra = false )
	{
		$this->_filters[] = array( $func, $keys, $type, $extra );
	}

And can call it using some of the following examples:

ini_add_filter ('ini_filter_replace_backticks');

ini_add_filter('ini_filter_split_commas_single', array(), 'regexp attrs', '/^(rule)(\s)?[0-9]{1,}(\s)?$/');

ini_add_filter('ini_filter_split_commas_single', array('rule 0', 'rule 1', 'rule 2', 'rule 3', 'rule 4'), 'in array attrs');

This is a class, ini_add_filter just returns $_GLOBALS['ini']->add_filter()

Works great, and allows me to add aditional filters, and I can filter attributes and values using reg expressions, an array of possible values, etc. The code is much shorter and efficient.

[Drakla]

I've got a pretty similar thing running with an emai parser with plugins. You might also want to look at this great introduction to design patterns on the Zend dev site (http://devzone.zend.com/public/view)

It leads into the Decorator pattern and various filtering methods which might give you some more great ideas. For instance your filters could be objects, not just functions and then you could set values for them, just like you're setting parameters in your function, and then pass the objects to your parser. This allows for expandability with overloading / inheritance - that's if you need things to go that in depth.

http://devzone.zend.com/node/view/id/3

[cgraz]

Thanks drakla! I had never heard of the decorator pattern, and it definately seems useful.

I did create this with the decorator pattern, but I couldn't get it to quite work the way I needed (probably lack of experience with the pattern).

Either way, what I did is structure my parser like this:

iniParser

METHODS
iniParser()
- Constructor
- Adds Default filter that replaces backtickw with quotes

add_filter()
- Manages the array that holds filters ($this->_filters)
- The array just holds the name of the class of each filter

parse()
- parses file into $contents using parse_ini_file()
- If There are any filters, loop through them, creates class, and runs
filter() method that each filter class has. Resets the value of $contents
after each filter so the filters build off of each other

clear_filters()
- resets $this->_filters and adds the default filter

---

iniFilter

METHODS
iniFilter()
- Constructor
- Sets $this->contents and $this->sections (true or false) so
child filters have access to.

Would have like to add a method called next that works similar to mysql_fetch_row
that would read down to 3 levels in my array, sometimes less depending on sections. Then
in my filters, I can call via

while($val = $this->next())
{
// Run Filter on Val
}

ideally $val would hold the key and value so I could run conditions on it.

I couldn't get this to work, so I manually loop through $contents using nested foreach loops
in each of my child filters. ehhh.... if anyone has ideas on this... 😉

---

Child classes

These just extend iniFilter and return the contents

METHODS

constructor
- executes parent::iniFilter( $contents, $sections ) so iniFilter parent will set
$this->contents and $this->sections

filter()
- runs the filter and returns the result

I also have addtional methods necessary for each filter

Thanks for your help. If you have any suggestions on the parser, let me know.