Code Generator CLI Tool

g is a tool for code generation. It is inspired by Giles Bowkett's talk Code Generation: The Safety Scissors of Metaprogramming. It's also worth mentioning that his talk was inspired by Rails, which was arguably inspired by the book Code Generation in Action.

Features

Generates code based on templates.
Supports custom transformations using JavaScript.
Can be used to generate anything, however, automatically formats generated Go code using gopls if installed.
Customizable configuration through YAML and JavaScript.

Installation

On mac or linux, run:

brew install quinn/tap/qg

Usage

Basic Command

qg -path <target-directory> <generator-name> [args...]

-path: Specifies the target directory containing the .g directory. Defaults to current directory.
generator-name: The name of the generator to run.
[args...]: Arguments required by the generator.

Example

qg my-generator arg1 arg2

Configuration

The configuration is defined in a g.yaml file located in the root directory specified by -path.

g.yaml Structure

version: "1.0"
generators:
  - name: "my-generator"
    args:
      - "arg1"
      - "arg2"
transforms:
  - myTransformFunction: "path/to/file"

version: The version of the configuration file.
generators: A list of generators.
name: The name of the generator.
args: A list of arguments required by the generator.
transforms: A list of transformations to apply.
myTransformFunction: The JavaScript function to apply.
path/to/file: The path to the file to transform.

Template Directory

Each generator should have a corresponding directory under .g//tpl containing the template files.

JavaScript Configuration

JavaScript config can be used to define additional k/v for templates. The config.js file should define a config function that takes cli arguments and returns additional configuration values.

function config(input) {
  return {
    additionalKey: "additionalValue",
  };
}

Example Project Structure

my-project/
├── g.yaml
├── .g/
│ └── my-generator/
│ ├── tpl/
│ │ ├── template.go.tpl
│ │ └── [additionalKey].go.tpl
│ └── config.js
└── main.go

Template File

Template files use Go's text/template syntax and can access variables from the configuration.

template.go.tpl:

package main

// imports can be omitted, and will be added automatically.

func main() {
    fmt.Println("Generated with arg1: {{ .arg1 }} and arg2: {{ .arg2 }}")
}

JavaScript Transformations

Transformations allow you to manipulate files using JavaScript functions.

config.js:

function config(input) {
  return {
    ...input,
    additionalKey: "additionalValue",
  };
}

function myTransformFunction(fileContent, config) {
  return fileContent.replace("PLACEHOLDER", config.additionalKey);
}

Development

Build

To build the CLI tool, run:

go build -o qg

Testing

To test the CLI tool, create test projects with the appropriate structure and run the tool with different configurations.

Contributing

Feel free to open issues or submit pull requests. Any contributions are welcome!

License

This project is licensed under the MIT License.

# README