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package main
import (
"bytes"
"errors"
"fmt"
"go/ast"
"go/parser"
"go/token"
"io"
"os"
"reflect"
"strings"
)
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]
}
func indent(s string) string {
var output bytes.Buffer
for _, line := range strings.SplitAfter(s, "\n") {
output.WriteByte('\t')
output.WriteString(line)
}
return output.String()
}
func run() error {
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
}
var output bytes.Buffer
output.WriteString("package ")
output.WriteString(f.Name.Name)
output.WriteByte('\n')
handlers := map[string]string{}
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 routeSpec string
if routeSpec, ok = strings.CutPrefix(hhRoute, "//hh:route "); !ok {
continue
}
handlers[routeSpec] = "hh_" + f.Name.String()
output.WriteString("\nfunc hh_")
output.WriteString(f.Name.String())
output.WriteString("[S any](s S, w http.ResponseWriter, r *http.Request) {")
parsedRequestType, ok := f.Type.Params.List[1].Type.(*ast.StructType)
if !ok {
return errors.New("Parsed request type must be a struct")
}
for _, field := range parsedRequestType.Fields.List {
for _, nameIdent := range field.Names {
typ := field.Type
name := nameIdent.Name
var tag string
if field.Tag != nil {
tag = reflect.StructTag(field.Tag.Value[1 : len(field.Tag.Value)-1]).Get("hh")
}
fmt.Println(typ, name, tag)
if t1, ok := typ.(*ast.StarExpr); ok {
if t2, ok := t1.X.(*ast.SelectorExpr); ok && t2.Sel.Name == "Request" {
if id, ok := t2.X.(*ast.Ident); ok && id.Name == "http" {
continue
}
}
}
if t1, ok := typ.(*ast.SelectorExpr); ok && t1.Sel.Name == "ResponseWriter" {
if id, ok := t1.X.(*ast.Ident); ok && id.Name == "http" {
continue
}
}
if tag == "" {
return errors.New("Don't know what to do with '" + name + "'. You must add a tag to specify")
}
tags := strings.Split(tag, ",")
// TODO: handle raw request. Or maybe that should be a separate parameter
optional := false
if tags[0] == "optional" {
optional = true
tags = tags[1:]
}
switch tags[0] {
case "form":
output.WriteString("\n\t")
output.WriteString(name)
output.WriteString(" := r.FormValue(\"")
output.WriteString(name)
output.WriteString("\")")
case "cookie":
output.WriteString("\n\tvar ")
output.WriteString(name)
output.WriteString(" string\n\t")
output.WriteString(name)
output.WriteString("0, _ := r.Cookie(\"")
output.WriteString(name) // TODO: optionally get cookie name from tags[1]
output.WriteString("\")\n\tif ")
output.WriteString(name)
output.WriteString("0 != nil {\n\t\t")
output.WriteString(name)
output.WriteString(" = ")
output.WriteString(name)
output.WriteString("0.Value\n\t}")
if !optional {
output.WriteString(" else {\n\t\tw.WriteHeader(http.StatusBadRequest)\n\t\tw.Write([]byte(`Bad request. Missing cookie '")
output.WriteString(name)
output.WriteString("'`))\n\t}")
}
default:
return errors.New("Unknown extractor " + tags[0])
}
output.WriteString("\n")
}
}
output.WriteString("\n\t")
output.WriteString(f.Name.Name)
output.WriteString("(w, ")
structDef := slice(fileContents, &fset, parsedRequestType.Pos(), parsedRequestType.End())
output.WriteString(indent(structDef)[1:])
output.WriteString("{")
for i, field := range parsedRequestType.Fields.List {
for j, nameIdent := range field.Names {
if i+j > 0 {
output.WriteString(", ")
}
typ := field.Type
name := nameIdent.Name
_, _ = typ, name
output.WriteString(name)
output.WriteString(": ")
output.WriteString(name)
}
}
output.WriteString("})\n")
output.WriteString("}\n")
}
io.Copy(os.Stdout, &output)
fmt.Println(handlers)
return nil
}
|
