Replacer

Replacer is a Go code generator that applies regex-based transformations to your source files. It is designed to work with Go's //go:generate directive, allowing you to automate repetitive code modifications.

Why?

I often need to repeat the same set of comments in my Go code. For example, I use swaggo to generate Swagger documentation for an API. My API endpoints always return the same headers, like X-API-Version or X-Request-ID. Unfortunately, there's no way to define common headers for all endpoints yet. Instead of manually copying and pasting these headers every time, I created replacer to automate this process. Now, I can simply write:

go // @COMMON-HEADERS

run go generate, which is a part of my build pipeline, and get:

go // @Header all {string} X-Request-ID "UUID of the request" // @Header all {string} X-API-Version "API version, e.g. v1alpha" // @Header all {int} X-Ratelimit-Limit "Rate limit value" // @Header all {int} X-Ratelimit-Remaining "Rate limit remaining" // @Header all {int} X-Ratelimit-Reset "Rate limit reset interval in seconds"

Why not use sed or awk?

In short, it's hard to maintain when you have a lot of transformations, rules look more complicated. Also, there is a huge issues with multi-platform support. Even, unix-like macos and linux have different versions of sed and awk.

IDE's snippets?

IDE's snippets are great, but it's hard to maintain them in a team. Also, it's hard to share them between different IDE's.

Features

• Full-featured regex (docs), including expands
• Automatically searches for a configuration file (.replacer.yml or .replacer.yaml) in the current directory and parent directories.
• Stops searching at the root directory or when a go.mod file is encountered.

Installation

To install replacer, run:

bash go install github.com/weastur/replacer/@latest

Make sure that $GOPATH/bin is in your $PATH.

Of course, you can also download the binary from the releases page

Usage

1. Create a configuration file (.replacer.yml or .replacer.yaml) in the root of your project or in the directory where you want to run replacer.

   ```yaml

   rules:

   • regex: '(?m)^\/\/ MY RULE$' repl: |- // MY NEW AWESOME // MULTI-LINE REPLACEMENT
   • regex: '(?m)^\/\/ MY 2 RULE$' repl: |- // REPLACEMENT No2
   • regex: '(?m)^\/\/ (?P\w+) are also work$' repl: |- // ${group} are great ```

2. Add a //go:generate directive to your source file. Despite config search mechanism, the transformation rules will be applied only to the file where the directive is placed.

   go //go:generate replacer

3. Run go generate to apply the transformations.

   bash go generate ./...

   Pay attention that generate command will only work if you have the replacer binary in your $PATH.

   Also, the go build command doesn't run go generate automatically. You need to run it manually. Refer to go help generate for more information.

4. Optional Flags:

- `-config` - specify the path to the configuration file.

    Example: `//go:generate replacer -config my-replacer-config.yml`

Configuration file search

If the -config flag is not provided, replacer will search for a configuration file in the following order:

1. The current directory.
2. Parent directories, moving up one level at a time.
3. Stops searching when it reaches the root directory or encounters a go.mod file.

Development

See CONTRIBUTING.md for information on how to contribute to replacer.

tl;dr

```bash

fork/clone the repository

install go

put some config in .replacer.yml

task build task test GOFILE=my-test-file.go replacer

commit/push/PR

```

Project structure

• main - the main command.
• config - handles configuration file parsing and validation.
• generator - applies regex-based transformations to source files.

Security

Refer to the SECURITY.md file for more information.

License

Mozilla Public License 2.0

Refer to the LICENSE file for more information.