[golang 模板] golang 模板 #golang #template

template.go

package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"strings"
	"text/template"
)

var (
	tplPath  = flag.String("tpl", "", "the template path")
	cfgPath  = flag.String("cfg", "", "the config path")
	destPath = flag.String("dest", "", "the dest path")
)

func main() {
	flag.Parse()

	// parse config
	data, err := os.ReadFile(*cfgPath)
	if err != nil {
		log.Fatal(err)
	}
	var cfg cfg
	err = json.Unmarshal(data, &cfg)
	if err != nil {
		log.Fatal(err)
	}

	// walk though files in tplPath, render them with cfg one by one
	filepath.Walk(*tplPath, func(path string, info fs.FileInfo, err error) error {
		if info.IsDir() {
			return nil
		}

		srcFilepath := newFilePath(path)
		dest := mkDest(srcFilepath, cfg)
		render(path, dest, cfg)
		return nil
	})

	remainder(cfg)
}

type cfg struct {
	Host   string `json:"host"`
	Job    string `json:"job"`
	JobNum string `json:"job_num"`
	// If true modify job-kuaikan by manual.
	IsDynamicDomains bool `json:"is_dynamic_domains"`
}

type filePath struct {
	dir             string
	base            string
	firstPartOfBase string
	secPartOfBase   string
}

func (f filePath) String() string {
	if len(f.secPartOfBase) > 0 {
		return filepath.Join(f.dir, fmt.Sprintf("%s.%s", f.firstPartOfBase, f.secPartOfBase))
	}
	return filepath.Join(f.dir, f.firstPartOfBase)
}

func mkDest(srcFilepath filePath, cfg cfg) string {
	// retain the directory struct of template
	subPath := strings.TrimPrefix(srcFilepath.dir, *tplPath)
	srcFilepath.dir = filepath.Join(*destPath, subPath)
	// rename
	srcFilepath.firstPartOfBase = newName(srcFilepath.firstPartOfBase, cfg)
	return srcFilepath.String()
}

func newFilePath(path string) (f filePath) {
	f = filePath{
		dir:  filepath.Dir(path),
		base: filepath.Base(path),
	}
	filename := strings.SplitN(f.base, ".", 2)
	f.firstPartOfBase = filename[0]
	if len(filename) > 1 {
		f.secPartOfBase = filename[1]
	}
	return
}

func newName(name string, cfg cfg) string {
	switch name {
	case "-job":
		return cfg.Job
	default:
		return name
	}
}

func render(src, dest string, data interface{}) {
	tpl, err := template.New(filepath.Base(src)).Funcs(template.FuncMap{
		"capital": strings.Title,
	}).ParseFiles(src)
	if err != nil {
		log.Fatal(err)
	}
	// create dest file
	os.MkdirAll(filepath.Dir(dest), 0777)
	file, err := os.Create(dest)
	if err != nil {
		log.Fatal(err)
	}

	// output render result to dest file
	err = tpl.Execute(file, data)
	if err != nil {
		log.Fatal(err)
	}
	file.Close()
}

func remainder(cfg cfg) {
	if cfg.IsDynamicDomains {
		log.Println("WARN: IsDynamicDomains is true, you may need to modify the config of job-kuaikan manually.")
	}
}

对 render 函数做了一些封装

func main() {
	if len(os.Args) < 3 {
		log.Fatal("need action and param")
	}
	switch os.Args[1] {
	case "render":
		if len(os.Args) < 5 {
			log.Fatal("need param")
		}
		data := make(map[string]string, len(os.Args[4:]))
		for _, item := range os.Args[4:] {
			split := strings.SplitN(item, "=", 2)
			data[split[0]] = split[1]
		}
		render(os.Args[2], os.Args[3], data)
	}
}

模板文件 ./config/a.json:

{{ .job }}

执行命令：

./script/script render ./config/a.json ./config/b.json job=hello