comby
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A code rewrite tool for structural search and replace that supports ~every language.
comby
See the usage documentation.
A short example below shows how comby simplifies matching and rewriting compared to regex approaches like sed
.
Comby supports interactive review mode (click here to see it in action).
Need help writing patterns or have other problems? Post them in Gitter.
Install (pre-built binaries)
Mac OS X
-
brew install comby
Ubuntu Linux
-
bash <(curl -sL get-comby.netlify.app)
-
Other Linux distributions: The PCRE library is dynamically linked in the Ubuntu binary. For other distributions like Arch Linux, a fixup is needed:
sudo ln -s /usr/lib/libpcre.so /usr/lib/libpcre.so.3
. On Fedora, usesudo ln -s /usr/lib64/libpcre.so /usr/lib64/libpcre.so.3
. Alternatively, consider building from source.
Windows
-
Install the Windows Subsystem for Linux and install Ubuntu. Then run
bash <(curl -sL get.comby.dev)
Docker
-
docker pull comby/comby
click to expand an example invocation for the docker image
Running with docker on stdin
:
docker run -a stdin -a stdout -a stderr -i comby/comby '(:[emoji] hi)' 'bye :[emoji]' lisp -stdin <<< '(👋 hi)'
![](https://user-images.githubusercontent.com/888624/64924862-0edf1a00-d7b7-11e9-9c2e-cfeafde5bb4b.png)
Or try it live.
Isn't a regex approach like sed good enough?
Sometimes, yes. But often, small changes and refactorings are complicated by nested expressions, comments, or strings. Consider the following C-like snippet. Say the challenge is to rewrite the two if
conditions to the value 1
. Can you write a regular expression that matches the contents of the two if condition expressions, and only those two? Feel free to share your pattern with @rvtond on Twitter.
if (fgets(line, 128, file_pointer) == Null) // 1) if (...) returns 0
return 0;
...
if (scanf("%d) %d", &x, &y) == 2) // 2) if (scanf("%d) %d", &x, &y) == 2) returns 0
return 0;
To match these with comby, all you need to write is if (:[condition])
, and specify one flag that this language is C-like. The replacement is if (1)
. See the live example.
Build from source
-
Install opam. TL;DR do
sh <(curl -sL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh)
-
Run this if you don't have OCaml installed (it bootstraps the OCaml compiler):
opam init
opam switch create 4.11.0 4.11.0
-
Run
eval $(opam env)
-
Install OS dependencies:
-
Linux:
sudo apt-get install autoconf libpcre3-dev pkg-config zlib1g-dev m4 libgmp-dev libev4 libsqlite3-dev
-
Mac:
brew install pkg-config gmp pcre libev
-
-
Then install the library dependencies:
git clone https://github.com/comby-tools/comby
cd comby
opam install . --deps-only
- Build and test
make
make test
- Install
comby
on yourPATH
by running
make install