In relatively short order, I was able to whip up some expressions to do custom refactorings across an entire codebase. Here are some examples:
- Replace two line declare and return pattern with one-line return
- Netbeans jackpot: { $stmts$; $type $value = $expr; return $value; } => { $stmts$; return $expr; }
- Move common trailing statements in if/else blocks outside the if
- Intellij SSR:
- Search pattern:
if($boolean_expression$) {
$trueStatements$;
$commonstmts$;
}
else {
$falseStatements$;
$commonstmts$;
} - Replace pattern:
if($boolean_expression$) {
$trueStatements$;
}
else {
$falseStatements$
}
$commonstmts$; - Improve the expressiveness of code by quickly introducing helper's for certain patterns
- Netbeans jackpot: {$type $var = $expr; $var.add($valueExpr); $remainingStmts$;} => {$type $var = Arrays.asList($valueExpr); $remainingStmts$;};
The possibilities of what you can search and replace with these pattern/ast based features is really impressive. As I showed some examples, my colleagues were continuously coming up with additional ideas for things we could do with this.
The Intellij SSR is a bit more polished but the jackpot rules language seems like a more flexible idea. Jackpot also lets you access a Java API to do transformations on code, though I think I hold off on learning that until I need to do a refactoring against a code base large enough to justify that time investment.
Intellij and Netbeans are using their AST (Abstract Syntax Tree) to provide this useful
functionality. I can only hope that Eclipse will catch up soon. In the meantime, one of the side-effects of the exercise was that it forced me to exercise some of the new maven integration capabilities of the latest IDE's. I've now got a fairly solid way to open a project in any of the 3 major IDE's (Eclipse, Netbeans, Intellij) without doing any special configuration. Here is the basic idea:
- Use a maven pom.xml to define project dependencies.
- To Use Eclipse: use the mvn eclipse:eclipse plugin to generate the eclipse project files.
- To Use Netbeans: Point Netbeans at the maven pom.
- To Use Intellij: Point Intellij at the maven pom.
