add support for advanced diff summary

[monperrus]

Nice points by @Symbolk

#112 (comment)

Why we diff? Because we want to understand the changes, so the format should serve for change comprehension. In fact, someone has modified Gumtree output format but getting a distingushed paper~ (See FudanSELab/CLDIFF)

I customized Gumtree for personal use, for meaningful diff summary, including:

Action Name
Parent Node Type: Target Node Type
Target Node Content Before Action
Line Range & Column Range Before Action
Target Node Content After Action (if exists)
Line Range & Column Range After Action (if exists)

For example:

Move
CompilationUnit::ImportDeclaration
import com.beust.jcommander.Parameter;
12, 273
import com.beust.jcommander.Parameter;
1, 0

So, basically you can read it as a phrase: "Move ImportDeclaration 'import com.beust.jcommander.Parameter;' in CompilationUnit from (12, 273) to (1, 0)".

#112 (comment)

I'd like to, but one major concern here.

As we know, Gumtree parses multple languages with various backends (parser), but for each of the supported languages, the definition of AST Node Type and the way to get ranges is different. Since I only use Gumtree to diff Java, so I only implement the Java version.

To generalize the output format, some refactoring must be done.

BTW, I made a pr earlier to fix a bug (#110 ), but it seems @jrfaller did not merge it.

[jrfaller]

I like very much this textual format. I think there is no problem to have it language independant since these informations are available in all our generators (and normally I took care that the range are homogeneously computed).

@Symbolk where can I read the code of your text formatter?

[Symbolk]

@jrfaller Ok, I will push my code to the forking repo (https://github.com/Symbolk/gumtree) by this weekend.

[jrfaller]

@Symbolk nice!!!

[jrfaller]

@Symbolk I guess this is commit Symbolk/gumtree@7fdc571 ? Thanks!

[Symbolk]

@Symbolk I guess this is commit Symbolk/gumtree@7fdc571 ? Thanks!

Yeah, but I only implemented the location info (i.e. Range) for Action and ITree and for Java currently, do you think it deserves a pull request, or other languages should be implemented?

[jrfaller]

Hi @Symbolk I have updated the textual output of diff using many of your ideas! Thanks for the discussion (and closing this issue).