{"id":1359,"date":"2012-04-11T09:21:05","date_gmt":"2012-04-11T08:21:05","guid":{"rendered":"http:\/\/www.sachaheck.net\/blog\/?p=1359"},"modified":"2012-04-12T15:05:18","modified_gmt":"2012-04-12T14:05:18","slug":"using-grep-to-tweak-epub","status":"publish","type":"post","link":"https:\/\/www.sachaheck.net\/blog\/digital-media\/using-grep-to-tweak-epub","title":{"rendered":"Using GREP to tweak EPUB-files"},"content":{"rendered":"

The last few weeks, I have been working on some EPUB-files which have been generated from InDesign CS4 some while ago. I believe it was December 2010. Tweaking the files with Sigil, I noticed, that there are many paragraphs which include a class generated by InDesign which is absolutely useless. Here is an excerpt of the HTML-file:<\/p>\n

\"\"<\/p>\n

Every paragraph contains a span class „generated-style“ which has been exported from InDesign. With exporting from InDesign CS5 or InDesign CS5.5 this doesn’t happen!<\/strong> When you have a look at the CSS, nothing is defined for this automatically generated class. So you really don’t need it and it only bloats your file.<\/p>\n

GREP to rescue<\/h2>\n

So what can you do about this issue? While this circumstance does not prevent your EPUB to work properly, you however may want to have a clean code. So I had this idea to do a search with GREP<\/a> and delete every entry of this useless class in the HTML-files. You know, regular expressions can be really awesome to do such kind of complicated search\/replace work. Many programmes already support GREP-Search, like InDesign too. But here in this case tweaking the EPUB-files, I’m working with Sigil<\/a> and BBEdit<\/a> which also understand regular expressions (or commonly also called regex).<\/p>\n

Well, I’m not a great Regex expert. I only use it for little things, but this challenge was already a bit more complicated. I don’t know any people around who are good at regex, so I started a request for help on twitter. Twitter<\/a> is really great to connect with geeks and experts around the world. So shortly after my request, Ahmad Moqanasa (@AbuGnais<\/a>) answered with a great search string. He’s a developer and geek from Amman<\/a> and he suggested the following:<\/p>\n

(<[^<>\/]*?class=\\\"generated-style\"[^<>\/]*?>)([^<>]*?)(<\/[^<>\/]*?>)<\/pre>\n
 <\/p>\n
Wow this looks complicated,\u00a0 doesn’t it? I can’t explain it to you, however I wanted to share this bit of GREP. So let’s see how this works. I entered this search string in BBEdit’s Find\/Replace dialogue (do not forget to check the GREP option). And you replace with the second match:\u00a0\\2.<\/p>\n
\"\"<\/p>\n
The expression finds the whole class „generated-style“ including its content. But replacing with the second match only deletes the class, not the content. The result is this:<\/p>\n
\"\"<\/p>\n
Ok, now we have a clean code and got rid of this superflous span class. I find this regex very helpful in this case. I don’t know if you can use this GREP too, but if you can use it, you know where to find it ;-)<\/p>\n
Do you know other cases where GREP could be helpful with EPUB-tweaking?<\/p>\n
EDIT<\/h2>\n
As Kai points out in the comments, this GREP is shorter and does also a very decent job. Check it out:<\/p>\n
Search: <span class=\"generated-style\">(.+?)<\/span><\/pre>\n
Replace: \\1<\/pre>\n