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https://github.com/rajasegar/codeshift

A Ruby CLI to transform source code using ASTs - A Ruby Codemod
https://github.com/rajasegar/codeshift

codemod codemods gem ruby-gem

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A Ruby CLI to transform source code using ASTs - A Ruby Codemod

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README 

        
# Codeshift



[![Gem Version](https://badge.fury.io/rb/codeshift.svg)](https://badge.fury.io/rb/codeshift)

[![Build Status](https://travis-ci.org/rajasegar/codeshift.svg?branch=master)](https://travis-ci.org/rajasegar/codeshift) 

![](https://ruby-gem-downloads-badge.herokuapp.com/codeshift?type=total&style=plastic&color=brightgreen&total_label=)

[![Coverage Status](https://coveralls.io/repos/github/rajasegar/codeshift/badge.svg?branch=master)](https://coveralls.io/github/rajasegar/codeshift?branch=master)



A Ruby codemod CLI to transform your source code using AST(Abstract Syntax Trees) and the [parser](https://github.com/whitequark/parser) gem. 

It is typically used on Ruby codebase like RAILS applications and other stuff.



## Installation



```sh

$ gem install codeshift

```



## Usage

This tool requires a `transform.rb` file which contains the transform logic to be 

applied on the source files in a folder.



```sh

$ codeshift -t [TRANSFORM FILE] [PATHS]

```



To apply the transform logic on your `app/models` files



```sh

$ codeshift -t transform.rb app/models

```



For example if you want to reverse the local variable names and method names in your code

you will be doing something like this:



Create a new Ruby file with the tranformation logic to be applied on the

AST of the source code. For writing transforms you can make use of 

[Ruby AST Explorer](https://ruby-ast-explorer.herokuapp.com/) and [cybertron](https://github.com/rajasegar/cybertron)



### transform.rb

```ruby

# Your Transform Class should always extend from 

# Parser:: TreeRewriter

class Transform < Parser::TreeRewriter

  def on_lvasgn(node)

    # Reverse the variable names

    replace(node.loc.name, node.children[0].to_s.reverse)

  end



  def on_def(node)

    replace(node.loc.name, node.children[0].to_s.reverse)

  end

end



```



If your source code looks like below in a folder called `~/Desktop/test/ruby`



### sample.rb

```ruby

tips = ["hello", "world"]

def print_tips

  tips.each { |key, value| print "Tip #{key}: #{value}" }

end

```



Then use the transform against your source code



```sh

$ codeshift -t transform.rb ~/Desktop/test/ruby

```



Then your source will be transformed something like:



### sample.rb

```ruby

spit = ["hello", "world"]

def spit_tnirp

  tips.each { |key, value| print "Tip #{key}: #{value}" }

end



```



## Options

Usage: codeshift -t  [path]

* --version                    Print version number

* -t, --transform=TRANSFORM        path to the transform file. Can be either a local path or url

             (default: ./transform.rb)

* -h, --help                       Prints this help



### transform-file

The transform file could be a local file or a remote url. For example you can use a remote transform like below:



```sh

$ codeshift -t https://gist.githubusercontent.com/[user]/.../transform.rb ~/Desktop/test/ruby

```



### path

The path could be a list of directories or files separated by space.



```sh

$ codeshift -t transform.rb ~/app/legacy/ruby ~/app/old

```



```sh

$ codeshift -t transform.rb ~/code/legacy/app/models/account.rb ~/old/app/models/customer.rb

```



## Related tools

- [ruby-ast-explorer](https://github.com/rajasegar/ruby-ast-explorer)

- [cybertron](https://github.com/rajasegar/cybertron)



## Development



After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.



To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).



## Contributing



Bug reports and pull requests are welcome on GitHub at https://github.com/rajasegar/codeshift. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.



## License



The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).



## Code of Conduct



Everyone interacting in the Codeshift project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/rajasegar/codeshift/blob/master/CODE_OF_CONDUCT.md).