close all opened tags

@SaveSheepMar 07.2006

I have a box where a user can input html…this html is later added to a webpage using php from mysql.

Is there a way I can have it search for all opened tags within their input..and make it close them?

For example…if a user makes a tag..but doesn’t close it at the end of their html, then the rest of my text on that page, beyond their input, will be bold. Make sense?

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PHP

@NogDogMar 07.2006 — #I'm sure it could be done, but it would not be trivial (see [url=http://www.w3.org/People/Raggett/tidy/]HTML Tidy[/url] for example). My recommendation might be to look into using BBCode such as is used on these forums. If you do a Google on "bbcode PHP" you'll get a few hits on the first page that include some open source php bbcode functions.

@SaveSheepauthorMar 07.2006 — #alright, so heres a question for you.

instead of doing something like that, what if i were to just put a </div></form> at the end to close up anything that may still be left open? Those are the only tags that are allowed.

would this screw anything up?

@NogDogMar 07.2006 — #It would definitely create invalid HTML. What any specific browser would do with it is undefined and therefore unpredictable.

For a simple validation, you could count each instance of each opening and closing tag, and if the totals don't match, raise an error and reject the input.

@aaronbdavisMar 07.2006 — #the way compilers generally work is by using a Stack. every time the compiler finds a {, it adds it to the stack. When it finds the corresponding }, it pops the { from the front. If you can find a Stack PHP Class you could do something similar and nuance it a bit.

Instead of simply pushing or popping, do some checking for what is being popped.

e.g. suppose you have the following string:
[code=html]blah blah bold text[/code]
you don't want to simply add the closing tag as this would be invalid. you want to end up with [code=html]blah blah bold text[/code]
I think this could probably be achieved by using two stacks: the first holds the unmatched open tags, and the second holds those closing tags which have been added to the text.

the above text example would run like this:
[list=1]

[*]feed the string into the parser

[*]add the tag to the Open Stack

[*]add the tag to the Open Stack

[*] is a closing tag so check the Open stack

[*]it does not match to to insert the tag into the actual string, then add the tag to the Closed Stack

[*] is matched to so pop from the stack

[*]now look at the Open and Closed Stacks: the in Open matches the in Closed so pop them both.

[/list]

close all opened tags

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