fix off-by-one error for sub command completion.

Fixes #97

1 files changed, 7 insertions, 6 deletions

diff --git a/args.go b/args.go
index 16e5ab3..3340285 100644
--- a/args.go
+++ b/args.go
@@ -85,16 +85,17 @@ func splitLastEqual(line []string) []string {
 	return append(line[:len(line)-1], parts...)
 }
 
+// from returns a copy of Args of all arguments after the i'th argument.
 func (a Args) from(i int) Args {
-	if i > len(a.All) {
-		i = len(a.All)
+	if i >= len(a.All) {
+		i = len(a.All) - 1
 	}
-	a.All = a.All[i:]
+	a.All = a.All[i+1:]
 
-	if i > len(a.Completed) {
-		i = len(a.Completed)
+	if i >= len(a.Completed) {
+		i = len(a.Completed) - 1
 	}
-	a.Completed = a.Completed[i:]
+	a.Completed = a.Completed[i+1:]
 	return a
 }