scanner: implement Peek() to look at the next char w/o advancing

R=rsc
CC=golang-dev
http://codereview.appspot.com/840045

1 files changed, 8 insertions, 0 deletions

diff --git a/src/pkg/scanner/scanner.go b/src/pkg/scanner/scanner.go
index 25544f667..f60a4eed2 100644
--- a/src/pkg/scanner/scanner.go
+++ b/src/pkg/scanner/scanner.go
@@ -282,6 +282,14 @@ func (s *Scanner) Next() int {
 }
 
 
+// Peek returns the next Unicode character in the source without advancing
+// the scanner. It returns EOF if the scanner's position is at the last
+// character of the source.
+func (s *Scanner) Peek() int {
+	return s.ch
+}
+
+
 func (s *Scanner) error(msg string) {
 	s.ErrorCount++
 	if s.Error != nil {