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|
package main
import (
"bytes"
"go/ast"
"go/format"
"go/parser"
"go/token"
"html/template"
"os"
"regexp"
"strings"
"github.com/pkg/errors"
)
const suffix = "_msg_gen.go"
type CommentBuilder struct {
file string
}
type GenBuilder struct {
err error
comments map[string]string
}
type FileBuilder struct {
content []byte
dst string
err error
}
func main() {
err := CommentBuilder{os.Getenv("GOFILE")}.
GetComments().
GenCode().
SaveCode()
checkErr(err)
}
func (c CommentBuilder) GetComments() GenBuilder {
if c.file == "" {
return GenBuilder{err: errors.New("file not specified")}
}
var comments = make(map[string]string)
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, c.file, nil, parser.ParseComments)
if err != nil {
return GenBuilder{err: err}
}
cmap := ast.NewCommentMap(fset, f, f.Comments)
for node := range cmap {
if spec, ok := node.(*ast.ValueSpec); ok && len(spec.Names) == 1 {
ident := spec.Names[0]
if ident.Obj.Kind == ast.Con {
comments[ident.Name] = parseComment(ident.Name, spec.Comment)
}
}
}
return GenBuilder{
comments: comments,
}
}
// gen 生成代码
func (g GenBuilder) GenCode() FileBuilder {
if g.err != nil {
return FileBuilder{err: g.err}
}
var buf = bytes.NewBufferString("")
data := map[string]interface{}{
"pkg": os.Getenv("GOPACKAGE"),
"comments": g.comments,
}
t, err := template.New("").Parse(tpl)
if err != nil {
return FileBuilder{
err: errors.Wrapf(err, "template init err"),
}
}
err = t.Execute(buf, data)
if err != nil {
return FileBuilder{
err: errors.Wrapf(err, "template data err"),
}
}
b, err := format.Source(buf.Bytes())
return FileBuilder{
dst: os.Getenv("GOFILE"),
content: b,
err: err,
}
}
func (f FileBuilder) SaveCode() error {
if f.err != nil {
return f.err
}
dstFile, err := os.OpenFile(
strings.ReplaceAll(f.dst, ".go", "")+suffix,
os.O_TRUNC|os.O_WRONLY|os.O_CREATE,
0644,
)
if err != nil {
return err
}
defer dstFile.Close()
_, err = dstFile.Write(f.content)
return err
}
// parseComment 获取注释信息，来自AST标准库的summary方法
func parseComment(name string, group *ast.CommentGroup) string {
if group == nil {
return ""
}
var buf bytes.Buffer
for _, comment := range group.List {
text := regexp.MustCompile(`//\s*`).ReplaceAllString(comment.Text, "")
buf.WriteString(text)
}
// replace any invisibles with blanks
bytes := buf.Bytes()
for i, b := range bytes {
switch b {
case '\t', '\n', '\r':
bytes[i] = ' '
}
}
return string(bytes)
}
func checkErr(err error) {
if err != nil {
panic(err)
}
}
// tpl 生成代码需要用到模板
const tpl = `
// Code generated by github.com/rnben/gen-const-msg DO NOT EDIT
// {{.pkg}} 错误码信息
package {{.pkg}}
// noErrorMsg 未知错误
const noErrorMsg = "unknown error"
// messages 错误码对应描述信息
var messages = map[int]string{
{{- range $key, $value := .comments}}
{{$key}}: "{{$value}}",{{end}}
}
// GetMsg 返回错误码描述
func GetMsg(code int) string {
var (
msg string
ok bool
)
if msg, ok = messages[code]; !ok {
msg = noErrorMsg
}
return msg
}
`
|
