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package main
import (
"bytes"
"errors"
"fmt"
"go/ast"
"go/parser"
"go/scanner"
"go/token"
"net/http"
"strconv"
"strings"
)
func main() {
if err := run(); err != nil {
panic(err)
}
}
func run() error {
var fset token.FileSet
f, err := parser.ParseFile(&fset, "examples/basic.go", nil, parser.ParseComments|parser.SkipObjectResolution)
if err != nil {
return err
}
for _, decl := range f.Decls {
f, ok := decl.(*ast.FuncDecl)
if !ok {
continue
}
hhRoute := f.Doc.List[len(f.Doc.List)-1].Text
var routeSpec string
if routeSpec, ok = strings.CutPrefix(hhRoute, "//hh:route "); !ok {
continue
}
rs, err := parseRouteSpec(routeSpec)
if err != nil {
return err
}
var wrapper bytes.Buffer
wrapper.WriteString("func httpWrapper_")
wrapper.WriteString(f.Name.String())
wrapper.WriteString("[S any](s S, r *http.Request, w http.ResponseWriter) {")
i := 0
for _, p := range f.Type.Params.List {
for _, n := range p.Names {
wrapper.WriteString("\n\tvar")
wrapper.WriteString(strconv.Itoa(i))
wrapper.WriteString(" := ")
wrapper.WriteString(n.Name)
i++
}
}
wrapper.WriteString("\t")
wrapper.WriteString(f.Name.Name)
wrapper.WriteString("(")
i = 0
for _, p := range f.Type.Params.List {
for range p.Names {
if i > 0 {
wrapper.WriteString(", ")
}
wrapper.WriteString("var")
wrapper.WriteString(strconv.Itoa(i))
i++
}
}
wrapper.WriteString(")\n")
wrapper.WriteString("}\n")
fmt.Printf("`%v`\n`%v`\n`%v`\n", routeSpec, f.Name.Name, rs)
}
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
}
|
