codegen

README

codegen - Utilities for Go code generators

Package codegen provides a Go API for writing Go code generators from a text/template.

const tmpl = `// Code generated by main.go; DO NOT EDIT.

package main

const x = {{ printf "%q" .str }}

var v = {{ printf "%#v" .array }}
`

func main() {
	codegen.MustParse(tmpl).CreateFile(
		"main_gen.go",
		map[string]any{
			"str":   `abcdef`,
			"array": []int{1, 2, 3},
		},
	)
}

Try on the Go Playground.

Features:

• The Go syntax is validated before saving.
• The output properly is reformatted thanks to gofmt.
• The Go standard for marking generated code (https://golang.org/s/generatedcode) is enforces.

See documentation and example.

License

Copyright 2016-2024 Olivier Mengué

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Documentation

Overview

Package codegen provides utilities for writing short Go code generators from a text/template.

Example

package main

import (
	"log"
	"os"

	"github.com/dolmen-go/codegen"
)

func main() {
	const template = `// Code generated by example_test.go; DO NOT EDIT.
{{/**/}}//+build {{.}}

package main

import "os"

func main() {
	os.Stdout.WriteString("Hello, {{.}}!\n")
}
`

	tmpl := codegen.MustParse(template)
	for _, tag := range os.Args[1:] {
		f := "main_" + tag + ".go"
		if err := tmpl.CreateFile(f, tag); err != nil {
			log.Fatal(err)
		}
		log.Printf("File %s created.\n", f)
	}
}

Index

• Variables
• func CreateFile(filePath string, t *template.Template, data interface{}) (err error)
• type CodeTemplate
  • func MustParse(codeTemplate string) *CodeTemplate
  • func Parse(codeTemplate string) (*CodeTemplate, error)
  • func (t *CodeTemplate) CreateFile(filePath string, data interface{}) error

Examples

• Package

Variables

var GeneratedCodeRegexp = regexp.MustCompile(`(?m:^// Code generated .* DO NOT EDIT\.$)`)

GeneratedCodeRegexp checks the code generation standard defined at https://golang.org/s/generatedcode.

Functions

func CreateFile

func CreateFile(filePath string, t *template.Template, data interface{}) (err error)

CreateFile runs the "text/template".Template with data, pass it through gofmt and saves it to filePath.

Types

type CodeTemplate

type CodeTemplate struct {
	Template *template.Template // See "text/template"
	Buffer   bytes.Buffer       // Used for sharing allocated memory between multiple CreateFile calls
	// contains filtered or unexported fields
}

CodeTemplate is the precompiled template for generating one or multiple Go source files.

func MustParse

func MustParse(codeTemplate string) *CodeTemplate

MustParse wraps Parse throwing errors as exception.

func Parse

func Parse(codeTemplate string) (*CodeTemplate, error)

Parse creates a CodeTemplate from a "text/template" source.

The expansion of the template is expected to be valid a Go source file containing the code generation standard tag. See GeneratedCodeRegexp.

func (*CodeTemplate) CreateFile

func (t *CodeTemplate) CreateFile(filePath string, data interface{}) error

CreateFile runs the template with data, pass it through gofmt and saves it to filePath.

The code generation standard at https://golang.org/s/generatedcode is enforced.