func updateStructTags()

in cmd/go-to-protobuf/protobuf/parser.go [393:464]
68 lines of code
18 McCabe index (conditional complexity)

func updateStructTags(decl ast.Decl, structTags map[string]map[string]string, toCopy []string) []error {
	var errs []error
	t, ok := decl.(*ast.GenDecl)
	if !ok {
		return nil
	}
	if t.Tok != token.TYPE {
		return nil
	}

	for _, s := range t.Specs {
		spec, ok := s.(*ast.TypeSpec)
		if !ok {
			continue
		}
		typeName := spec.Name.Name
		fieldTags, ok := structTags[typeName]
		if !ok {
			continue
		}
		st, ok := spec.Type.(*ast.StructType)
		if !ok {
			continue
		}

		for i := range st.Fields.List {
			f := st.Fields.List[i]
			var name string
			var err error
			if len(f.Names) == 0 {
				name, err = getFieldName(f.Type, spec.Name.Name)
				if err != nil {
					errs = append(errs, err)
					continue
				}
			} else {
				name = f.Names[0].Name
			}
			value, ok := fieldTags[name]
			if !ok {
				continue
			}
			var tags customreflect.StructTags
			if f.Tag != nil {
				oldTags, err := customreflect.ParseStructTags(strings.Trim(f.Tag.Value, "`"))
				if err != nil {
					errs = append(errs, fmt.Errorf("unable to read struct tag from struct %q, field %q: %v", spec.Name.Name, name, err))
					continue
				}
				tags = oldTags
			}
			for _, name := range toCopy {
				// don't overwrite existing tags
				if tags.Has(name) {
					continue
				}
				// append new tags
				if v := reflect.StructTag(value).Get(name); len(v) > 0 {
					tags = append(tags, customreflect.StructTag{Name: name, Value: v})
				}
			}
			if len(tags) == 0 {
				continue
			}
			if f.Tag == nil {
				f.Tag = &ast.BasicLit{}
			}
			f.Tag.Value = tags.String()
		}
	}
	return errs
}