moth/pkg/namesubfs/namesubfs.go

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2022-05-10 13:20:54 -06:00
package namesubfs
import (
"io/fs"
"log"
"path"
)
// Sub returns a NameSubFS corresponding to the subtree rooted at fsys's dir.
func NameSub(fsys fs.FS, dir string) (*NameSubFS, error) {
switch f := fsys.(type) {
case *NameSubFS:
return f.NameSub(dir)
default:
baseFS := &NameSubFS{fsys, ""}
return baseFS.NameSub(dir)
}
}
// A NameSubFS is a file system allowing the query of the full path name of entries
type NameSubFS struct {
fs.FS
dir string
}
// FullName returns the path to name.
//
// This is not the absolute path!
// It is relative to whatever was provided to the initial Sub call.
func (f *NameSubFS) FullName(name string) string {
return path.Join(f.dir, name)
}
// NameSub returns a NameSubFS corresponding to the subtree rooted at dir.
func (f *NameSubFS) NameSub(dir string) (*NameSubFS, error) {
log.Println("Sub", f.dir)
newFS, err := fs.Sub(f.FS, dir)
if err != nil {
return nil, err
}
newNameSubFS := NameSubFS{
FS: newFS,
dir: f.FullName(dir),
}
return &newNameSubFS, err
}
// NameSub returns an FS corresponding to the subtree rooted at dir.
func (f *NameSubFS) Sub(dir string) (fs.FS, error) {
return f.NameSub(dir)
}