php regex preg_match_all issue

Question

I'm trying to figure out a problem I'm having with regex.

I'm using this regex with preg_match_all on a large multi line string:

 /(\{(if|while|function|loop|\$|#)(.+)\})/

It currently works to match all text that starts with { and ends with } such as {$test} or {$function="test()"}

However, if one line in the string contains two matching blocks, the regex returns the whole line such as:

{$value.url}" class="link">{$value.title}

I can't figure out how to make the regex not do a 'greedy' match with (.+). The reason why I have (.+) is because there could be any character/number/underscore/period/quote/space in between the two brackets {}.

Can someone help me out?

Is this also validating or supporting nesting, what should happen if the string was {if {$fish} do } — Bob Vale
– Bob Vale, Commented Jul 29, 2011 at 11:29
That is a good question, however we are using a templating engine that doesn't use nested {}, your example would be {if="$fish"}This is a {$fish}{/if}. We just needed a quick request to scan all our files to find out which files had the if/while/etc statements in them. — Joe
– Joe, Commented Jul 29, 2011 at 11:48

stema · Accepted Answer · 2011-07-29 11:23:20Z

1

You can make the .+ ungreedy by adding a question mark like this .+?

answered Jul 29, 2011 at 11:23

stema

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Ted Kulp · Accepted Answer · 2011-07-29 11:21:03Z

1

Try matching for everything except for the } and then the }.

/(\{(if|while|function|loop|\$|#)([^\}]+)\})/

answered Jul 29, 2011 at 11:21

Ted Kulp

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3 Comments

Bob Vale Over a year ago

That would break nesting (eg. {if {fish} do} would return {if {fish}

Ted Kulp Over a year ago

I think any non-greedy match will break nesting. I would have to imagine at that point that simple regex wouldn't cut it and it would move into full token parser type stuff. But I could be wrong.

Bob Vale Over a year ago

True, but you could require no open brace instead so [^\{\}] which would then at least match a balanced pair on the inner nest

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