protogen-lib

README

protogen-lib

A lightweight Go library for writing Protocol Buffer code generators (protoc plugins) without depending on the standard protogen package. This library provides a clean, minimal interface for creating protoc plugins with built-in support for command-line options parsing and file generation.

Features

• Declarative options parsing: Declare the protogen options similar to cobra / urfavecli's Flags
• Customizable Request Validation: Provide custom validation logic to your options to ensure correct input
• Customizable Codegen: Control how the codegen transforms the Proto File's AST into output files

Installation

go get github.com/junpeng-jp/protogen-lib

Quick Start

Here's a minimal example of a protoc plugin using protogen-lib:

package main

import (
    "fmt"
    "github.com/junpeng-jp/protogen-lib/command"
    "github.com/junpeng-jp/protogen-lib/opts"
)

func main() {
    var outputDir string
    var verbose bool
    
    cmd := &command.GenerateCommand{
        Name:    "my-plugin",
        Version: "1.0.0",
        Options: []opts.Option{
            &opts.StringOption{
                Name:        "output_dir",
                Default:     ".",
                Destination: &outputDir,
            },
            &opts.BoolOption{
                Name:        "verbose",
                Default:     false,
                Destination: &verbose,
            },
        },
        Generate: func(pl *command.PluginContext) error {
            for _, file := range pl.Files {
                if !pl.FilesToGenerate[file.GetName()] {
                    continue
                }
                
                // Generate output file
                outFile := pl.NewGeneratedFile(file.GetName() + ".generated.go")
                outFile.Fprint("// Generated code for", file.GetName())
                outFile.Fprint("package", file.GetPackage())
                // ... more generation logic
            }
            return nil
        },
    }
    
    if err := cmd.Run(); err != nil {
        panic(err)
    }
}

Usage with protoc

Once compiled, the plugin can be used with protoc:

protoc --plugin=protoc-gen-my-plugin=./my-plugin \
       --my-plugin_out=output_dir=./gen,verbose=true:. \
       *.proto

Feature Coverage

A non-exhaustive list of features that are not yet implemented.

Some might be implemented in the future.

Feature	protogen-lib	protogen
Option Parsing	string & boolean	✅
Option Validation	✅	✅
Pre-processing of Codegen Request	❌	✅
Annotations	❌	✅
Source Code Info	❌	✅
Comments	❌	✅
...