How to get the content between two self-defined tags?

I'm trying to write a simple template system, and I have a problem. If I have a string like this:

{% for x in xx %}
    some string 1
{% endfor %}

{% for y in yy %}
    some string 2
{% endfor %}

How could I get the contents some string 1 and some string 2. I try to match them with the regular expression, which looks for {% for .+ in .+ %} and {% endfor %} and get the contents between them, but in this case, what it got is:

    some string 1
{% endfor %}

{开发者_Go百科% for y in yy %}
    some string 2

What should I do?

UPDATE:

I think what I need is a regular expression which can do things like this:

count = 0
while not the end:
    if match("{% for .+ in .+ %}")
        count += 1
    else if match("{% endfor %}")
        count -= 1
    if count == 0 
        // get contents between the first {% for in %} and the last {% endfor %}

Can regular expression count?

PHP already makes an excellent templating system, why do you want to complicate it further by relying on what will become a VERY complicated RegEx if you want a decent templating system.

Chances are you're using .* somewhere in your regex, which is greedy. Try using .*? instead, which is non-greedy.

(Also, for any kind of tag nesting, you aren't going to want to use regex like that; instead you'll need to actually have some kind of stack involved.)