diff options
-rw-r--r-- | src/bufio/scan.go | 4 | ||||
-rw-r--r-- | src/bufio/scan_test.go | 36 |
2 files changed, 39 insertions, 1 deletions
diff --git a/src/bufio/scan.go b/src/bufio/scan.go index c5714f331..a41451524 100644 --- a/src/bufio/scan.go +++ b/src/bufio/scan.go @@ -112,7 +112,9 @@ func (s *Scanner) Scan() bool { // Loop until we have a token. for { // See if we can get a token with what we already have. - if s.end > s.start { + // If we've run out of data but have an error, give the split function + // a chance to recover any remaining, possibly empty token. + if s.end > s.start || s.err != nil { advance, token, err := s.split(s.buf[s.start:s.end], s.err != nil) if err != nil { s.setErr(err) diff --git a/src/bufio/scan_test.go b/src/bufio/scan_test.go index 3ddb25acf..1454a8113 100644 --- a/src/bufio/scan_test.go +++ b/src/bufio/scan_test.go @@ -419,3 +419,39 @@ func TestScanWordsExcessiveWhiteSpace(t *testing.T) { t.Fatalf("unexpected token: %v", token) } } + +// Test that empty tokens, including at end of line or end of file, are found by the scanner. +// Issue 8672: Could miss final empty token. + +func commaSplit(data []byte, atEOF bool) (advance int, token []byte, err error) { + for i := 0; i < len(data); i++ { + if data[i] == ',' { + return i + 1, data[:i], nil + } + } + if !atEOF { + return 0, nil, nil + } + return 0, data, nil +} + +func TestEmptyTokens(t *testing.T) { + s := NewScanner(strings.NewReader("1,2,3,")) + values := []string{"1", "2", "3", ""} + s.Split(commaSplit) + var i int + for i = 0; i < len(values); i++ { + if !s.Scan() { + break + } + if s.Text() != values[i] { + t.Errorf("%d: expected %q got %q", i, values[i], s.Text()) + } + } + if i != len(values) { + t.Errorf("got %d fields, expected %d", i, len(values)) + } + if err := s.Err(); err != nil { + t.Fatal(err) + } +} |