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package main
import (
"bytes"
"errors"
"fmt"
"go/ast"
"go/parser"
"go/scanner"
"go/token"
"io"
"net/http"
"os"
"reflect"
"slices"
"strconv"
"strings"
)
func main() {
if err := run(); err != nil {
panic(err)
}
}
func slice(fileContents string, filePosInfo *token.File, start token.Pos, end token.Pos) string {
return fileContents[filePosInfo.Position(start).Offset:filePosInfo.Position(end).Offset]
}
func run() error {
filename := "examples/basic.go"
fileBytes, err := os.ReadFile(filename)
if err != nil {
return err
}
// fileContents := string(fileBytes)
var fset token.FileSet
fp := fset.AddFile(filename, -1, len(fileBytes))
_ = fp
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')
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
}
split := strings.Split(routeSpec, " ")
var method, path string
if len(split) == 1 {
path = split[0]
} else if len(split) == 2 {
method = split[0]
path = split[1]
} else {
return errors.New("Invalid route spec. Expected `//hh:route [method] [path]` or `//hh:route [path]`")
}
if !slices.ContainsFunc([]string{
"",
http.MethodGet,
http.MethodHead,
http.MethodPost,
http.MethodPut,
http.MethodPatch,
http.MethodDelete,
http.MethodConnect,
http.MethodOptions,
http.MethodTrace,
}, func(m string) bool { return m == method }) {
return errors.New("Invalid http method " + method)
}
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)
tags := strings.Split(tag, ",")
// TODO: handle raw request. Or maybe that should be a separate parameter
if len(tags) == 0 {
return errors.New("Don't know what to do with '" + name + "'. You must add a tag to specify")
}
switch tags[0] {
case "form":
output.WriteString("\n\t")
output.WriteString(name)
output.WriteString(" := r.FormValue(\"")
output.WriteString(name)
output.WriteString("\")")
case "cookie":
// panic("todo")
}
}
}
i := 0
output.WriteString("\n\t")
output.WriteString(f.Name.Name)
output.WriteString("(w, ")
i = 0
for _, field := range parsedRequestType.Fields.List {
for _, nameIdent := range field.Names {
typ := field.Type
name := nameIdent.Name
if i > 0 {
output.WriteString(", ")
}
output.WriteString("var")
output.WriteString(strconv.Itoa(i))
i++
}
}
output.WriteString(")\n")
output.WriteString("}\n")
fmt.Printf("`%v`\n`%v`\n", path, f.Name.Name)
}
io.Copy(os.Stdout, &output)
return nil
}
type routeSpec struct {
method string
path string
parameters []routeSpecParam
}
type routeSpecParam struct {
name string
extractor string
}
func parseRouteSpec(s string) (routeSpec, error) {
s = strings.TrimRight(s, " \n")
var rs routeSpec
for _, method := range []string{
http.MethodGet,
http.MethodHead,
http.MethodPost,
http.MethodPut,
http.MethodPatch,
http.MethodDelete,
http.MethodConnect,
http.MethodOptions,
http.MethodTrace,
} {
if rest, ok := strings.CutPrefix(s, method+" "); ok {
s = rest
rs.method = method
break
}
}
for {
if commaPos := strings.IndexByte(s, ','); commaPos != -1 {
rs.path = s[:commaPos]
s = s[commaPos+1:]
} else {
rs.path = s
return rs, nil
}
s = strings.TrimLeft(s, " ")
if s == "" {
break
}
end := -1
for i := 0; i < len(s); i++ {
if 'a' <= s[i] && s[i] <= 'z' ||
'A' <= s[i] && s[i] <= 'Z' ||
s[i] == '_' {
continue
}
if s[i] == ':' {
end = i
break
}
return rs, errors.New("Expected ':' to mark end of parameter name, got " + s[i:i+1])
}
if end == -1 {
return rs, errors.New("Expected ':' to mark end of parameter name, got end of line")
}
var p routeSpecParam
p.name = s[:end]
s = s[end+1:]
s = strings.TrimLeft(s, " ")
expr, err := parser.ParseExpr(s)
if el, ok := err.(scanner.ErrorList); err == nil || ok && el[0].Msg == "expected 'EOF', found ','" {
switch expr := expr.(type) {
case *ast.Ident:
switch expr.Name {
case "query":
p.extractor = ":" + expr.Name
default:
return rs, errors.New("Unexpected extractor " + expr.Name)
}
case *ast.CallExpr:
p.extractor = s[expr.Pos()-1 : expr.End()-1]
default:
return rs, errors.New("Unexpected extractor" + s[expr.Pos()-1:expr.End()-1])
}
} else {
return rs, err
}
s = s[expr.End()-1:]
rs.parameters = append(rs.parameters, p)
}
return rs, nil
}
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