go/token: document deserialization property

FileSet deserialization (Read) uses its own instance of a gob decoder.
If the FileSet data may be followed by other data on the reader, Read
may consume too much data that is lost unless the reader implements
ReadByte.

Also: Minor internal refactoring for symmetry.

R=r
CC=golang-dev
https://golang.org/cl/5233041

diff --git a/src/pkg/go/token/serialize.go b/src/pkg/go/token/serialize.go
index 80a3323f949a97288bddcfd61efa3092892a0805..5fb47f7cbb214278e3ad7097dcf0b3b18f788db0 100644 (file)
--- a/src/pkg/go/token/serialize.go
+++ b/src/pkg/go/token/serialize.go
@@ -24,10 +24,19 @@ type serializedFileSet struct {
        Files []serializedFile
 }
 
+func (s *serializedFileSet) Read(r io.Reader) os.Error {
+       return gob.NewDecoder(r).Decode(s)
+}
+
+func (s *serializedFileSet) Write(w io.Writer) os.Error {
+       return gob.NewEncoder(w).Encode(s)
+}
+
 // Read reads the fileset from r into s; s must not be nil.
+// If r does not also implement io.ByteReader, it will be wrapped in a bufio.Reader.
 func (s *FileSet) Read(r io.Reader) os.Error {
        var ss serializedFileSet
-       if err := gob.NewDecoder(r).Decode(&ss); err != nil {
+       if err := ss.Read(r); err != nil {
                return err
        }
 
@@ -58,5 +67,5 @@ func (s *FileSet) Write(w io.Writer) os.Error {
        ss.Files = files
        s.mutex.Unlock()
 
-       return gob.NewEncoder(w).Encode(ss)
+       return ss.Write(w)
 }