Instead you can use this regex: ^\[ [^\]]* \]

Which always matches an opening bracket, other characters and then the closing bracket, so in the example above it will never match more than the [a]

(whitespaces added for clarity, you need the /x modifier if you want to keep them).

While you are on the subject of lookaheads, this

   $code =~ s/\n//g;      #remove all the newlines
   $code .= "\n";         #add one to the end
[download]

could be replaced by this

   $code =~ s/\n(?=.)//g  # remove all but the last newline
[download]

I hope this is of interest.

Cheers,

JohnGG

Your replacement isn't equivalent to the code you claim it can replace. First of all, your code will not remove a newline followed by a newline - you'd need (?=(?s:.)) for that, or the /s modifier. Second, the original code will always let $code end with a newline; regardless whether it ended with a newline. In your replacement, there will only be a trailing newline in $code if there was one originally.

Good catch re. the s modifier, I missed that. Thanks for the correction.

With regard to your second point, from the way the OP initialised $code I don't think always ending with a newline was the requirement s/he was addressing. For the more general case you are correct.

Cheers,

JohnGG

So I'm thankful for the help!

First off: deMize « he »

Second, I'm not sure what I did was the best way of going about things. What I'm doing is just building a CMS insertion page with as little markup as possible, where each section is contained in it's own div.


Response:
The first problem was getting each into their own div, which the lookahead helped. To accomplish this, it just ends the current div when it hits a new section (may be a subsection in the future).

The reason for removing the line breaks was because I was using that as a delimiter for the last section --- there is probably a better way of doing that with determining the end of the string in the RegEx (maybe $), but I need to replace those line breaks with HTML breaks anyhow.


The problem:
This means that it is going to be linear with no sub-divs. I might have to rethink that for later, because I might want to have something like this later:


[section]
[top]Top Data
[middle]Mid Data
[bottom]Bottom Data

[section]
[top]Top Data
[bottom]Bottom Data
[download]



Should result to:

<div class="section">
   <div class="top">Top Data</div>
   <div class="middle">Middle Data</div>
   <div class="bottom">Bottom Data</div>
</div>
<div class="section">
   <div class="top">Top Data</div>
   <div class="bottom">Bottom Data</div>
</div>
[download]


What I plan to do is store either the sub sections in an array or the sections in an array. I could probably use help with a better algorithm.
The whole purpose of this was so that I could quickly type the data into one input box, without building a whole intricate interface (that can come later).

Try this code:

my $code = <<EOT;
[head]
Head text...

[body]
Body text...

[something else]
more text..
EOT

$code =~ s/[\n ]+?(?=\S)//sg; #remove all newlines but last

formatCode($code);

sub formatCode {
    my $str = shift;

    $str =~ s{ \[ ([^\]]+) \] ([^\]]*) (?=\[|\n)}
             {<div class="$1">$2</div>}igx;

    print $str;
}
[download]

I took your code, mixed in some of the suggestions of others, and made some changes I hope you find useful (since you asked). First, I changed the quoting to a "here doc", which is more like the file you'll probably be reading from in most situations.

Then I made a slight change to the way suggested below of removing the newlines, using a zero-width positive lookahead assertion (look up "?=" in perldoc perlre). The changes I made also accommodate blank lines in the source, which will help with readability.

Finally, in the regex, I used the /x modifier and curly braces to aid in the readability, and used a class, so you're now looking for "bracket, (not a bracket)+, bracket, (not a bracket)*, stop before a bracket".

Using "+" in the first capture and "*" in the second capture enforces an assumption (that you should think about and modify to suit) that brackets ALWAYS have a div name in them, but there might be no text after it. If there must always be text after a div name, use the "+" in both cases.

Since you are a professed newbie, I'll tell you that this is a common technique when you're learning. Later, you'll find it more practical (especially with large files) to process a stream, rather than manipulate a huge string. So, I'll leave you with this:

my $code = <<EOT;
[head]
Head text...

[body]
Body text...

[something else]
more text..
EOT

$prev_header = 0; # takes care of closing divs
for (split /\n/, $code) {               # No need to remove newlines
    if (/^\s*$/) { next }               # Skip blank lines

    elsif ( /^\[ ([^\]]+) \]/x ) {      # If line is a header...
        print "</div>" if $prev_header; #   close prev div, if there w
+as one...
        print qq(<div class="$1">);     #   print current div...
        $prev_header = 1;               #   and set current div flag.
    }

    else { print "$1 " }                # Simply print non-header line
+s
}
print "</div>"; # You always have to close last div, so just do it her
+e
[download]

To read from a file:

open, $FH, "<whatever.txt";
for (<$FH>) {
    chomp;
    ...
}
[download]

Nice remarks! I will have to try this when I get home.


As for the stream, you are right. Also, I wouldn't say I'm a newbie and I guess novice was incorrect to say as well; if I had to call my level something, I guess I should have said a previous amateur, never reaching the expert or monkism, but a little better than a neophyte.

I've done much of this stuff before, but have since forgot. Hence, me opening the thread looking for help, but then remembering the "lookahead" was what I was after.

The issue here is that I'm going to have to manipulate this in the future. For simplicity I made the delimiters: ([]) and (\n), which may or may not have nested text. So, I used (.*) on purpose because I might want to include something in a blank div for formatting.

I know I could just write everything in HTML-like syntax, or possibly some made up pseudo-SGML, like Wiki, but that would both take the fun away and increase my typing time. -- Something just interests me about having one label.

One of my concerns is that I wanted it to be efficient. I think streaming is the best choice - no question with lengthy strings.

I don't recall what backtracking is, so I'm going to have to evaluate what moritz was talking about with: /^\[ ([^\]]+) \]/x I vaguely remember an issue like what he said with ab, but for some reason I thought the non-greedy (?) would take that away.

Okay so after looking at it, it looks like: ([^\]]+) is basically saying, match anything not a close-bracket. I would use a (*) instead of a (+) for the reason of the empty div discussed above.

I question whether (?>) might be of use


Additionally, I don't know how I would stream the text. It's a parameter passed from a webform.

Just so everyone knows, some changes needed to be made:


The updated routine:

   sub formatCode{
      my $code = shift;
      my $prev_header = 0;                     # takes care of closing
+ divs
      for (split /\n/, $code) {                # No need to remove new
+lines
         if (/^\s*$/) { next }                 # Skip blank lines
         elsif ( /^(.*?)\[ ([^\]]*) \](.*)/x ) {      # If line is a h
+eader...
            print "$1</div>" if $prev_header;  #   close prev div, if 
+there was one...
            print qq(<div class="$2">$3);      #   print current div..
+.
            $prev_header = 1;                  #   and set current div
+ flag.
         }
         else { print "$_<br />" }             # Simply print non-head
+er lines
      }
      print "</div>" if $prev_header;          # You always have to cl
+ose last div, so just do it here
   }
[download]


Basically $1 needed to be changed to $_. Also, I added matches for before and after the tag, in case there was inline text. Finally, the line break was added in replace of a newline character. I'm still curious if $prev_header should be reset to 0 after the close div has been called. I guess it's not necessary.

Update:
Looking at it now, this is not going to work.
If I wish to have all the input on one line, I'd still need the look ahead. For example, the above solution will not fix multiple inline statements [head]Title Text[body]Blah Blah Blah

In replace of the lookahead, I can think of two simple solutions using split: I'd either need to first loop through the string and place an inline character before each [\w*] pattern, or I can delimit on the pattern itself.

So this is what I came up with:


   sub formatCode2{
      my $code = shift;
      my @arrCode = split (/\[([^\]]*)\]/, $code);
      my $size = @arrCode;

    # print whatever b4 1st delimiter
      if (@arrCode >= 1) {
         $_ = $arrCode[0];
         s/\n/<br \/>/ig;
         print qq(<div class="">$_</div>);
      }
    # print sections
      for (my $cnt = 1; $cnt < @arrCode; $cnt+=2){
         $_ = $arrCode[$cnt+1];
         s/\n/<br \/>/ig;          

         print qq(<div class="$arrCode[$cnt]">$_</div>);
      }
   }
[download]