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|
package main
import (
_ "embed"
"errors"
"go/ast"
"go/parser"
"go/token"
"os"
"reflect"
"strings"
"text/template"
)
//go:embed templates.go.tmpl
var fileTemplateString string
func main() {
if err := run(); err != nil {
panic(err)
}
}
func slice(fileContents string, fset *token.FileSet, start token.Pos, end token.Pos) string {
return fileContents[fset.Position(start).Offset:fset.Position(end).Offset]
}
type File struct {
PackageName string
Functions []Function
}
type Function struct {
Name string
Pattern string
RequestTypeDef string
RequestTypeFields []RequestTypeField
DoParseForm bool
}
type RequestTypeField struct {
Name string
Extractor string
Optional bool
NameInReq string
TypeDef string
}
func run() error {
fileTemplate, err := template.New("").Funcs(template.FuncMap{
"quote": func(s string) string {
return `"` + strings.NewReplacer(`\`, `\\`, `"`, `\"`, "\n", `\n`).Replace(s) + `"`
},
"error": func() struct{} {
panic("error")
},
}).Parse(fileTemplateString)
if err != nil {
return err
}
filename := "examples/basic.go"
fileBytes, err := os.ReadFile(filename)
if err != nil {
return err
}
fileContents := string(fileBytes)
var fset token.FileSet
f, err := parser.ParseFile(&fset, "examples/basic.go", fileBytes, parser.ParseComments|parser.SkipObjectResolution)
if err != nil {
return err
}
parsedFile := File{PackageName: f.Name.Name}
for _, decl := range f.Decls {
f, ok := decl.(*ast.FuncDecl)
if !ok {
continue
}
if f.Doc == nil {
continue
}
hhRoute := f.Doc.List[len(f.Doc.List)-1].Text
var pattern string
if pattern, ok = strings.CutPrefix(hhRoute, "//hh:route "); !ok {
continue
}
parsedRequestType, ok := f.Type.Params.List[1].Type.(*ast.StructType)
if !ok {
return errors.New("Parsed request type must be a struct")
}
parsedFunction := Function{
Name: f.Name.Name,
Pattern: pattern,
RequestTypeDef: slice(fileContents, &fset, parsedRequestType.Pos(), parsedRequestType.End()),
}
for _, field := range parsedRequestType.Fields.List {
for _, nameIdent := range field.Names {
typ := field.Type
parsedField := RequestTypeField{
Name: nameIdent.Name,
Extractor: "",
Optional: false,
TypeDef: slice(fileContents, &fset, typ.Pos(), typ.End()),
}
if parsedField.TypeDef == "*http.Request" {
parsedFunction.RequestTypeFields = append(parsedFunction.RequestTypeFields, parsedField)
continue
}
var tag string
if field.Tag != nil {
tag = reflect.StructTag(field.Tag.Value[1 : len(field.Tag.Value)-1]).Get("hh")
}
if tag == "" {
return errors.New("Don't know what to do with '" + parsedField.Name + "'. You must add a `hh:\"...\"` tag to specify")
}
tags := strings.Split(tag, ",")
if tags[0] == "optional" {
parsedField.Optional = true
tags = tags[1:]
}
if len(tags) == 0 {
return errors.New("Must specify extractor for '" + parsedField.Name + "' in `" + tag + "`")
}
parsedField.Extractor = tags[0]
tags = tags[1:]
switch parsedField.Extractor {
case "form":
parsedFunction.DoParseForm = true
case "cookie":
default:
return errors.New("Unknown extractor '" + tags[0] + "' on field " + nameIdent.Name)
}
if len(tags) >= 1 {
parsedField.NameInReq = tags[0]
tags = tags[1:]
} else {
parsedField.NameInReq = parsedField.Name
}
if len(tags) > 0 {
return errors.New("Unexpected rest of tag '" + tags[0] + "' in tag `" + tag + "` on field " + nameIdent.Name)
}
parsedFunction.RequestTypeFields = append(parsedFunction.RequestTypeFields, parsedField)
}
}
parsedFile.Functions = append(parsedFile.Functions, parsedFunction)
}
fileTemplate.Execute(os.Stdout, parsedFile)
return nil
}
|
