go/token: remove dependency on encoding/gob

R=dsymonds
CC=golang-dev
https://golang.org/cl/5636053

src/cmd/godoc/index.go

@@ -867,7 +867,10 @@ func (x *Index) Write(w io.Writer) error {
 		return err
 	}
 	if fulltext {
-		if err := x.fset.Write(w); err != nil {
+		encode := func(x interface{}) error {
+			return gob.NewEncoder(w).Encode(x)
+		}
+		if err := x.fset.Write(encode); err != nil {
 			return err
 		}
 		if err := x.suffixes.Write(w); err != nil {
@@ -897,7 +900,10 @@ func (x *Index) Read(r io.Reader) error {
 			return err
 		}
 		x.suffixes = new(suffixarray.Index)
-		if err := x.suffixes.Read(r); err != nil {
+		decode := func(x interface{}) error {
+			return gob.NewDecoder(r).Decode(x)
+		}
+		if err := x.suffixes.Read(decode); err != nil {
 			return err
 		}
 	}

src/pkg/go/token/serialize.go

@@ -4,11 +4,6 @@
 
 package token
 
-import (
-	"encoding/gob"
-	"io"
-)
-
 type serializedFile struct {
 	// fields correspond 1:1 to fields with same (lower-case) name in File
 	Name  string
@@ -23,19 +18,10 @@ type serializedFileSet struct {
 	Files []serializedFile
 }
 
-func (s *serializedFileSet) Read(r io.Reader) error {
-	return gob.NewDecoder(r).Decode(s)
-}
-
-func (s *serializedFileSet) Write(w io.Writer) 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) error {
+// Read calls decode to deserialize a file set into s; s must not be nil.
+func (s *FileSet) Read(decode func(interface{}) error) error {
 	var ss serializedFileSet
-	if err := ss.Read(r); err != nil {
+	if err := decode(&ss); err != nil {
 		return err
 	}
 
@@ -53,8 +39,8 @@ func (s *FileSet) Read(r io.Reader) error {
 	return nil
 }
 
-// Write writes the fileset s to w.
-func (s *FileSet) Write(w io.Writer) error {
+// Write calls encode to serialize the file set s.
+func (s *FileSet) Write(encode func(interface{}) error) error {
 	var ss serializedFileSet
 
 	s.mutex.Lock()
@@ -66,5 +52,5 @@ func (s *FileSet) Write(w io.Writer) error {
 	ss.Files = files
 	s.mutex.Unlock()
 
-	return ss.Write(w)
+	return encode(ss)
 }

src/pkg/go/token/serialize_test.go

@@ -6,6 +6,7 @@ package token
 
 import (
 	"bytes"
+	"encoding/gob"
 	"fmt"
 	"testing"
 )
@@ -69,12 +70,18 @@ func equal(p, q *FileSet) error {
 
 func checkSerialize(t *testing.T, p *FileSet) {
 	var buf bytes.Buffer
-	if err := p.Write(&buf); err != nil {
+	encode := func(x interface{}) error {
+		return gob.NewEncoder(&buf).Encode(x)
+	}
+	if err := p.Write(encode); err != nil {
 		t.Errorf("writing fileset failed: %s", err)
 		return
 	}
 	q := NewFileSet()
-	if err := q.Read(&buf); err != nil {
+	decode := func(x interface{}) error {
+		return gob.NewDecoder(&buf).Decode(x)
+	}
+	if err := q.Read(decode); err != nil {
 		t.Errorf("reading fileset failed: %s", err)
 		return
 	}