alexandremahdhaoui / genutils

Utilities for writing Go code generators

genutils

Utilities for writing Go code generators.

Getting Started

The genutils command line tool is used to generate code for writing generators. Run the following command to initialize a generator command line tool, that will be used to generate code using 2 markers.

go run github.com/alexandremahdhaoui/genutils/cmd/genutils@latest --cmd gencmd --generators="yourgen:./pkg/gen,anothergen:./pkg/gen"

Cmd

// cmd/yourgen/main.go
package main

import (
	genutils "github.com/alexandremahdhaoui/genutils"
	gen "github.com/alexandremahdhaoui/genutils/pkg/gen"
)

const (
	name                    = "gencmd"
	description             = "TODO: Please write a description here."
	helper                  = "TODO: Please write an example here."
	yourgenGeneratorName    = "yourgen"
	anothergenGeneratorName = "anothergen"
)

func main() {
	genutils.
		New(name).
		WithDescription(description).
		WithHelper(helper).
		WithGenerator(yourgenGeneratorName, gen.YourgenGenerator{}).
		WithGenerator(anothergenGeneratorName, gen.AnothergenGenerator{}).
		Apply().
		Run()
}

Generator

// pkg/yourgen/yourgen.go
package gen

import (
	genall "sigs.k8s.io/controller-tools/pkg/genall"
	markers "sigs.k8s.io/controller-tools/pkg/markers"
)

var yourgenMarkerDefinition = markers.Must(markers.MakeDefinition("gencmd:yourgen", markers.DescribesType, YourgenGenerator{}))

type YourgenGenerator struct {
	HeaderFile string `marker:",omitempty"`
	Year       string `marker:",omitempty"`
}

func (YourgenGenerator) RegisterMarkers(into *markers.Registry) error {
	if err := markers.RegisterAll(into, yourgenMarkerDefinition); err != nil {
		return err
	}
	into.AddHelp(yourgenMarkerDefinition, markers.SimpleHelp("object", ""))
	return nil
}

func (g YourgenGenerator) Generate(ctx *genall.GenerationContext) error {
	// TODO: ADD YOUR CODE HERE
	for _, root := range ctx.Roots {
		root.NeedTypesInfo()
		markerSet, err := markers.PackageMarkers(ctx.Collector, root)
		if err != nil {
			return err
		}
		markerValues := markerSet[yourgenMarkerDefinition.Name]
		if len(markerValues) == 0 {
			continue
		}
		// TODO: YOU CAN ALSO ADD YOUR CODE HERE
	}
	// TODO: OR HERE
	return nil
}

Use your new generator

Use it on a struct

//+gencmd:yourgen

type YourStruct struct{}

Execute your generator

//go:generate go run github.com/username/repo/cmd/gencmd@latest

package yourpkg