Vim replace expressions

Today I discovered the the existence of evaluated expressions as replacements in vim. Consider the following snippet

String tStr = request.getParameter("frmAmt_D_DR");
if ( tStr != null && !"".equals(tStr.trim()) ) {
  xxxDDrAmt = Double.parseDouble(trStr);
}

In this I want to transform the Double.parseDouble line to

xxxDDrAmt = parseLocalizedDouble(request, "frmAmt_D_DR", locale);

The change had to be done in a lot of files and I was racking my brains trying to figure out a macro to do this. I even tried to match the entire snippet but, ran into trouble with both approaches especially because the if condition could include other conditions and there might also be more than one limits that had to be processed. Then I found some obscure comment somewhere in one of the my numerous entreaties to google that referred to evaluated expression in the replacement giving me my Eureka! moment :). Since all the variable names were always some contraction of the actual input parameter name all I needed to do was to device an expression that constructed the parameter name from the variable name. Its long and ugly but gets the job done :D

:g/Double\.parseDouble/s/\(\w\+Amt\w*\).*$/\= submatch(1) . " = parseLocalizedDouble(request, \"frm_" . toupper(strpart(submatch(1), 3, 1)) . "_" . toupper(strpart(submatch(1), 4, 2)) . (strlen(strpart(submatch(1), 9)) > 1 ? "_" . strpart(submatch(1), 9) : "") . "\", locale);"/

Running this,

xxxDDrAmt = Double.parseDouble(trStr);

becomes

xxxDDrAmt = parseLocalizedDouble(request, "frm_D_DR", locale);

and

xxxDDrAmtUSD = Double.parseDouble(trStr);

becomes

xxxDDrAmtUSD = parseLocalizedDouble(request, "frm_D_DR_USD", locale);

Here is an annotated version but don't try using this one vim expects the entire thing to be in a single line :|

:g/Double\.parseDouble/                       # global search for double parsing
s/\(\w\+Amt\w*\).*$                           # search for variable names containing Amt
/\= submatch(1)                               # submatch(1) gives the first group
  . " = parseLocalizedDouble(request, \"frm_" # . is the string concatenation operator
  . toupper(strpart(submatch(1), 3, 1)) . "_" # strpart is the substr equivalent in vim
  . toupper(strpart(submatch(1), 4, 2))
  . (strlen(strpart(submatch(1), 9)) > 1      # don't change Amts to _S :)
    ? "_" . strpart(submatch(1), 9) : "")     # vim even supports the ternary operator ^_^
  . "\", locale);"
/

vi vi vi is the editor of the beast

I'm never satisfied with the text-editors I've been using so far. But, now I may have found _the one_. I started off with the humble MS-DOS edit, moved on to the GUI notepad then tried some serious text editors like EditPad, EditPlus, TextPad, SciteFlash, jEdit, Notepad++ and lots of others. There is always some feature that I really like accompanied with some equally irritating annoyance. Like for e.g. I love the beanshell find/replace in jEdit but, I had to give it up as it would choke for any file a little over 900KB. Editplus was great till I had to move to linux and Editpad was just too clunky.

I've used vi on and off mostly to quickly edit some file on the server to save the hassle of ftping the file back and forth. I never enjoyed these sessions much because I wasn't yet initiated to the magic of vi. Then one day I decided that all this brouhaha about vi and emacs must have some substance to it and hence resolved to use one of them as my primary editor henceforth. Its a tall order to master each of these editors but, since I was already familiar with vi and couldn't bear the ctrl+meta sequences of emacs for too long. For over 2 months now I've uninstalled every other text editor and use only gVim.

Its great. Everything you ever wanted to do with a piece of text can be done in vi. There are a wealth of cheatsheets and tutorials. Here are some of them.

Best of VIM Tips, gVIM's Key Features zzapper
A slightly advanced Introduction to Vim LG #152
Vi Reference Card
100 Vim commands every programmer should know

vi may be the editor of the beast because once you get to know it you start seeing its inner beauty :)