undo CL 4964067 / 661cb84cc6f0

API change. Needs further reflection.

??? original CL description
path/filepath: Simplify Walk interface

The last argument of filepath.Walk was removed, and the Visitor
interface now contains an Error method that is called on errors.

Fixes issue 2237.

R=golang-dev, gri, r
CC=golang-dev
http://codereview.appspot.com/4964067

Committer: Robert Griesemer <gri@golang.org>
???

R=r
CC=golang-dev
http://codereview.appspot.com/4974065

2 files changed, 31 insertions, 24 deletions

diff --git a/src/pkg/path/filepath/path.go b/src/pkg/path/filepath/path.go
index d6a7d08e8..3d5b915c1 100644
--- a/src/pkg/path/filepath/path.go
+++ b/src/pkg/path/filepath/path.go
@@ -255,14 +255,14 @@ func Abs(path string) (string, os.Error) {
 }
 
 // Visitor methods are invoked for corresponding file tree entries
-// visited by Walk.
+// visited by Walk. The parameter path is the full path of f relative
+// to root.
 type Visitor interface {
 	VisitDir(path string, f *os.FileInfo) bool
 	VisitFile(path string, f *os.FileInfo)
-	Error(path string, err os.Error)
 }
 
-func walk(path string, f *os.FileInfo, v Visitor) {
+func walk(path string, f *os.FileInfo, v Visitor, errors chan<- os.Error) {
 	if !f.IsDirectory() {
 		v.VisitFile(path, f)
 		return
@@ -274,11 +274,13 @@ func walk(path string, f *os.FileInfo, v Visitor) {
 
 	list, err := readDir(path)
 	if err != nil {
-		v.Error(path, err)
+		if errors != nil {
+			errors <- err
+		}
 	}
 
 	for _, e := range list {
-		walk(Join(path, e.Name), e, v)
+		walk(Join(path, e.Name), e, v, errors)
 	}
 }
 
@@ -314,14 +316,18 @@ func (f fileInfoList) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
 // v.VisitFile for each directory or file in the tree, including root.
 // If v.VisitDir returns false, Walk skips the directory's entries;
 // otherwise it invokes itself for each directory entry in sorted order.
-// Walk calls v.Error if an error happens while reading a directory.
-func Walk(root string, v Visitor) {
+// An error reading a directory does not abort the Walk.
+// If errors != nil, Walk sends each directory read error
+// to the channel.  Otherwise Walk discards the error.
+func Walk(root string, v Visitor, errors chan<- os.Error) {
 	f, err := os.Lstat(root)
 	if err != nil {
-		v.Error(root, err)
+		if errors != nil {
+			errors <- err
+		}
 		return // can't progress
 	}
-	walk(root, f, v)
+	walk(root, f, v, errors)
 }
 
 // Base returns the last element of path.
diff --git a/src/pkg/path/filepath/path_test.go b/src/pkg/path/filepath/path_test.go
index 8c566c700..395b12775 100644
--- a/src/pkg/path/filepath/path_test.go
+++ b/src/pkg/path/filepath/path_test.go
@@ -299,30 +299,30 @@ func mark(name string) {
 	})
 }
 
-type TestVisitor chan os.Error
+type TestVisitor struct{}
 
-func (v TestVisitor) VisitDir(path string, f *os.FileInfo) bool {
+func (v *TestVisitor) VisitDir(path string, f *os.FileInfo) bool {
 	mark(f.Name)
 	return true
 }
 
-func (v TestVisitor) VisitFile(path string, f *os.FileInfo) {
+func (v *TestVisitor) VisitFile(path string, f *os.FileInfo) {
 	mark(f.Name)
 }
 
-func (v TestVisitor) Error(path string, err os.Error) {
-	v <- err
-}
-
 func TestWalk(t *testing.T) {
 	makeTree(t)
 
-	v := make(TestVisitor, 64)
+	// 1) ignore error handling, expect none
+	v := &TestVisitor{}
+	filepath.Walk(tree.name, v, nil)
+	checkMarks(t)
 
-	// 1) no errors expected.
-	filepath.Walk(tree.name, v)
+	// 2) handle errors, expect none
+	errors := make(chan os.Error, 64)
+	filepath.Walk(tree.name, v, errors)
 	select {
-	case err := <-v:
+	case err := <-errors:
 		t.Errorf("no error expected, found: %s", err)
 	default:
 		// ok
@@ -343,13 +343,14 @@ func TestWalk(t *testing.T) {
 		tree.entries[1].mark--
 		tree.entries[3].mark--
 
-		// 2) expect two errors
+		// 3) handle errors, expect two
+		errors = make(chan os.Error, 64)
 		os.Chmod(filepath.Join(tree.name, tree.entries[1].name), 0)
-		filepath.Walk(tree.name, v)
+		filepath.Walk(tree.name, v, errors)
 	Loop:
 		for i := 1; i <= 2; i++ {
 			select {
-			case <-v:
+			case <-errors:
 				// ok
 			default:
 				t.Errorf("%d. error expected, none found", i)
@@ -357,7 +358,7 @@ func TestWalk(t *testing.T) {
 			}
 		}
 		select {
-		case err := <-v:
+		case err := <-errors:
 			t.Errorf("only two errors expected, found 3rd: %v", err)
 		default:
 			// ok