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Comby - Structural code search and replace for every language

196 points by WallyFunk 4y ago

picardo 4y ago
Superb tool. I used Comby to create a massive (3000+ changes) PR in which I ported JS type annotations into TS typings.
slightknack 4y ago
I mocked up a prototype for something similar to this using TreeSitter and its query language the other day for some heavy refactoring I had to do. This looks like a really cool project, will have to try it out!
adamesque 4y ago
I believe Sourcegraph uses Comby under the hood to an extent for structural matching as well!
- vanesa- 4y ago
  Yep! (Sourcegraph Community Manager here) We use Comby syntax for structural search: https://docs.sourcegraph.com/code_search/reference/structural https://docs.sourcegraph.com/code_search/reference/structura... We also have a few tutorials to make large-scale code changes across many repositories and code hosts (batch changes) with Comby: - Refactor Go code using Comby: https://docs.sourcegraph.com/batch_changes/tutorials/refactor_go_comby https://docs.sourcegraph.com/batch_changes/tutorials/refacto... - Updating Go import statements using Comby: https://docs.sourcegraph.com/batch_changes/tutorials/updating_go_import_statements https://docs.sourcegraph.com/batch_changes/tutorials/updatin... The author of Comby is a researcher at Sourcegraph building our search platform.
  - deleted 4y ago
    [deleted]
kretaceous 4y ago
Okay wow. I didn't tools like this existed! There's been more than once where I've found myself in a situation like "find all code like this, change if this, delete if this". Regex can only get you so far. Does someone know if this or something similar is available as a VSCode extension? It'd be fun to make one if not!
- ducktective 4y ago
  language-server methods like rename
  - kretaceous 4y ago
    Yes. I regularly use this feature sky-high I was looking for something more advanced as vanesa- spoke in the sibling comment.
    - kretaceous 4y ago
      - sky-high + but Swiping fiasco. When do we get the edit comment feature in HN? :)
      - vore 4y ago
        You should be able to edit comments within 2? hours of posting. Maybe this link works for you? https://news.ycombinator.com/edit?id=31417626 https://news.ycombinator.com/edit?id=31417626
- vanesa- 4y ago
  Sourcegraph Community Manager here. You can use the Sourcegraph extension for VSCode [1] that would allow you to have the structural search powered by Comby (or literal or regular expression search) inside of VSCode. You can't do batch changes[2] inside of VSCode yet, only via the Sourcegraph CLI[3]. We're working on expanding this. [1] https://marketplace.visualstudio.com/items?itemName=sourcegraph.sourcegraph https://marketplace.visualstudio.com/items?itemName=sourcegr... [2] https://docs.sourcegraph.com/batch_changes/explanations/introduction_to_batch_changes https://docs.sourcegraph.com/batch_changes/explanations/intr... [3] https://docs.sourcegraph.com/cli https://docs.sourcegraph.com/cli
marcodiego 4y ago
License? Also, how does it compare to Coccinelle?
- smallnix 4y ago
  License seems to be apache V2, see https://github.com/comby-tools/comby/blob/master/LICENSE https://github.com/comby-tools/comby/blob/master/LICENSE. They have a comparison section in their faq (https://comby.dev/docs/faq https://comby.dev/docs/faq): "Coccinelle uses a declarative syntax for matching constructs like function calls, if-statements, expression blocks, and so on for the C language. Some notable differences are that Coccinelle provides a patch-like format to express transformations (handy when you want to inline smaller changes in a broader context) and metavariable declarations (handy for developing and organizing more sophisticated patterns). For an example, see the file null_ref.cocci. Coccinelle works only for the C language, and may struggle to parse files that contain non-standard C constructs, like GCC inline assembly. Recent Coccinelle work has started expanding support for Java. In contrast, Comby’s syntax targets a wide range of languages and is more robust to matching patterns in the presence of unrecognized constructs. Comby is more suited to writing quick find-replace patterns for languages beyond C, and works well on C languages too."
CrazyPyroLinux 4y ago
This looks a lot like https://semgrep.dev/ https://semgrep.dev/ Interesting that they are both largely OCaml.
- jjice 4y ago
  ML style languages handle tree structures and traversal so well, I'm wondering if that's a large reason for using it.
feanaro 4y ago
A more interesting comparison than with Coccinelle is with semgrep (https://semgrep.dev/ https://semgrep.dev/) since it also supports semantic/structural pattern matching over a number of languages, but also adds in a bunch of Boolean logic into the mix, as well as some more advanced semantic features like constant propagation. Curious whether the teams behind these tools are aware of each other? I suppose it's unlikely that they're not.
- LesZedCB 4y ago
  yeah i just discovered semgrep a week ago! i'll have to download this and compare. i found the CLI features lacking in semgrep (vs using a yaml config), so maybe this will have more support there.
- carlmr 4y ago
  Comby works with C++, which to me is a great advantage.
  - fourthark 4y ago
    Semgrep has "experimental" support for C++. My understanding is that the major gap with both C & C++ support is macros, which are really hard.
jedisct1 4y ago
No support for Zig :(
- psanford 4y ago
  Odd, since the page linked says: > Dedicated parsers refine how Comby understands code, but it also has basic out-of-the-box support for data formats like JSON, recent languages like Zig, or your own DSLs!
otherflavors 4y ago
s/every language/some languages/

196 points by WallyFunk 4y ago

Superb tool. I used Comby to create a massive (3000+ changes) PR in which I ported JS type annotations into TS typings.

I mocked up a prototype for something similar to this using TreeSitter and its query language the other day for some heavy refactoring I had to do. This looks like a really cool project, will have to try it out!

adamesque 4y ago

I believe Sourcegraph uses Comby under the hood to an extent for structural matching as well!

vanesa- 4y ago
Yep! (Sourcegraph Community Manager here) We use Comby syntax for structural search: https://docs.sourcegraph.com/code_search/reference/structural https://docs.sourcegraph.com/code_search/reference/structura... We also have a few tutorials to make large-scale code changes across many repositories and code hosts (batch changes) with Comby: - Refactor Go code using Comby: https://docs.sourcegraph.com/batch_changes/tutorials/refactor_go_comby https://docs.sourcegraph.com/batch_changes/tutorials/refacto... - Updating Go import statements using Comby: https://docs.sourcegraph.com/batch_changes/tutorials/updating_go_import_statements https://docs.sourcegraph.com/batch_changes/tutorials/updatin... The author of Comby is a researcher at Sourcegraph building our search platform.
- deleted 4y ago
  [deleted]

kretaceous 4y ago

Okay wow. I didn't tools like this existed! There's been more than once where I've found myself in a situation like "find all code like this, change if this, delete if this". Regex can only get you so far. Does someone know if this or something similar is available as a VSCode extension? It'd be fun to make one if not!

ducktective 4y ago
language-server methods like rename
- kretaceous 4y ago
  Yes. I regularly use this feature sky-high I was looking for something more advanced as vanesa- spoke in the sibling comment.
  - kretaceous 4y ago
    - sky-high + but Swiping fiasco. When do we get the edit comment feature in HN? :)
    - vore 4y ago
      You should be able to edit comments within 2? hours of posting. Maybe this link works for you? https://news.ycombinator.com/edit?id=31417626 https://news.ycombinator.com/edit?id=31417626
vanesa- 4y ago
Sourcegraph Community Manager here. You can use the Sourcegraph extension for VSCode [1] that would allow you to have the structural search powered by Comby (or literal or regular expression search) inside of VSCode. You can't do batch changes[2] inside of VSCode yet, only via the Sourcegraph CLI[3]. We're working on expanding this. [1] https://marketplace.visualstudio.com/items?itemName=sourcegraph.sourcegraph https://marketplace.visualstudio.com/items?itemName=sourcegr... [2] https://docs.sourcegraph.com/batch_changes/explanations/introduction_to_batch_changes https://docs.sourcegraph.com/batch_changes/explanations/intr... [3] https://docs.sourcegraph.com/cli https://docs.sourcegraph.com/cli

marcodiego 4y ago

License? Also, how does it compare to Coccinelle?

smallnix 4y ago
License seems to be apache V2, see https://github.com/comby-tools/comby/blob/master/LICENSE https://github.com/comby-tools/comby/blob/master/LICENSE. They have a comparison section in their faq (https://comby.dev/docs/faq https://comby.dev/docs/faq): "Coccinelle uses a declarative syntax for matching constructs like function calls, if-statements, expression blocks, and so on for the C language. Some notable differences are that Coccinelle provides a patch-like format to express transformations (handy when you want to inline smaller changes in a broader context) and metavariable declarations (handy for developing and organizing more sophisticated patterns). For an example, see the file null_ref.cocci. Coccinelle works only for the C language, and may struggle to parse files that contain non-standard C constructs, like GCC inline assembly. Recent Coccinelle work has started expanding support for Java. In contrast, Comby’s syntax targets a wide range of languages and is more robust to matching patterns in the presence of unrecognized constructs. Comby is more suited to writing quick find-replace patterns for languages beyond C, and works well on C languages too."

CrazyPyroLinux 4y ago

This looks a lot like https://semgrep.dev/ https://semgrep.dev/ Interesting that they are both largely OCaml.

jjice 4y ago
ML style languages handle tree structures and traversal so well, I'm wondering if that's a large reason for using it.

feanaro 4y ago

A more interesting comparison than with Coccinelle is with semgrep (https://semgrep.dev/ https://semgrep.dev/) since it also supports semantic/structural pattern matching over a number of languages, but also adds in a bunch of Boolean logic into the mix, as well as some more advanced semantic features like constant propagation. Curious whether the teams behind these tools are aware of each other? I suppose it's unlikely that they're not.

LesZedCB 4y ago
yeah i just discovered semgrep a week ago! i'll have to download this and compare. i found the CLI features lacking in semgrep (vs using a yaml config), so maybe this will have more support there.
carlmr 4y ago
Comby works with C++, which to me is a great advantage.
- fourthark 4y ago
  Semgrep has "experimental" support for C++. My understanding is that the major gap with both C & C++ support is macros, which are really hard.

jedisct1 4y ago

No support for Zig :(

psanford 4y ago
Odd, since the page linked says: > Dedicated parsers refine how Comby understands code, but it also has basic out-of-the-box support for data formats like JSON, recent languages like Zig, or your own DSLs!

otherflavors 4y ago

s/every language/some languages/