diff options
Diffstat (limited to 'src/bufio/scan.go')
| -rw-r--r-- | src/bufio/scan.go | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/bufio/scan.go b/src/bufio/scan.go index a41451524..364d15961 100644 --- a/src/bufio/scan.go +++ b/src/bufio/scan.go @@ -36,6 +36,7 @@ type Scanner struct { start int // First non-processed byte in buf. end int // End of data in buf. err error // Sticky error. + empties int // Count of successive empty tokens. } // SplitFunc is the signature of the split function used to tokenize the @@ -108,6 +109,8 @@ func (s *Scanner) Text() string { // After Scan returns false, the Err method will return any error that // occurred during scanning, except that if it was io.EOF, Err // will return nil. +// Split panics if the split function returns 100 empty tokens without +// advancing the input. This is a common error mode for scanners. func (s *Scanner) Scan() bool { // Loop until we have a token. for { @@ -125,6 +128,15 @@ func (s *Scanner) Scan() bool { } s.token = token if token != nil { + if s.err == nil || advance > 0 { + s.empties = 0 + } else { + // Returning tokens not advancing input at EOF. + s.empties++ + if s.empties > 100 { + panic("bufio.Scan: 100 empty tokens without progressing") + } + } return true } } @@ -172,6 +184,7 @@ func (s *Scanner) Scan() bool { break } if n > 0 { + s.empties = 0 break } loop++ |