From 7a4713a35318a3884238ca112633817809d4d03f Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@geeks.cl>
Date: Fri, 24 Oct 2014 07:34:34 +0200
Subject: [PATCH] scanner.Scanner: add StepBack(), Reset() and Skip() methods

Signed-off-by: Alejandro Mery <amery@geeks.cl>
---
 scanner/scanner.go | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/scanner/scanner.go b/scanner/scanner.go
index 2a2676b..7addb55 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -54,6 +54,26 @@ func (l *Scanner) StepForth(runes, bytes uint) {
 	l.runes += runes
 }
 
+// Move cursor backward
+func (l *Scanner) StepBack(runes, bytes uint) {
+	l.cursor.Offset -= bytes
+	// FIXME: what if column goes < 1?
+	l.cursor.Column -= runes
+	l.runes -= runes
+}
+
+// Moves the cursor back to the back
+func (l *Scanner) Reset() {
+	l.cursor = l.base
+	l.runes = 0
+}
+
+// Trashes everything up to the cursor
+func (l *Scanner) Skip() {
+	l.base = l.cursor
+	l.runes = 0
+}
+
 // Return the next rune but not moving the cursor
 func (l *Scanner) Peek() (rune, uint) {
 	if l.cursor.Offset == uint(len(l.input)) {