groot/{rcmd,rtree}: handle Geant4 recovery baskets

groot/rcmd/dump_test.go

@@ -164,6 +164,27 @@ func TestDump(t *testing.T) {
 [002][x]: [[10] [] [10 20]]
 [003][x]: [[20 -21 -22]]
 [004][x]: [[200] [-201] [202]]
+`,
+		},
+		{
+			// Geant4 w/ recover baskets
+			name: "../testdata/g4-like.root",
+			want: `key[000]: mytree;1 "my title" (TTree)
+[000][i32]: 1
+[000][f64]: 1
+[000][slif64]: []
+[001][i32]: 2
+[001][f64]: 2
+[001][slif64]: [1]
+[002][i32]: 3
+[002][f64]: 3
+[002][slif64]: [2 3]
+[003][i32]: 4
+[003][f64]: 4
+[003][slif64]: [3 4 5]
+[004][i32]: 5
+[004][f64]: 5
+[004][slif64]: [4 5 6 7]
 `,
 		},
 	} {

groot/rtree/bkreader.go

@@ -58,12 +58,17 @@ func newBkReader(b Branch, n int, beg, end int64) *bkreader {
 		name:   b.Name(),
 	}
 
-	for i, seek := range base.basketSeek {
-		bkr.spans[i] = rspan{
-			pos: seek,
-			sz:  base.basketBytes[i],
-			beg: base.basketEntry[i],
-			end: base.basketEntry[i+1],
+	if len(base.basketEntry) == len(base.basketSeek) {
+		// prepare for recover basket mode.
+		base.basketEntry = append(base.basketEntry, 0)
+	} else {
+		for i, seek := range base.basketSeek {
+			bkr.spans[i] = rspan{
+				pos: seek,
+				sz:  base.basketBytes[i],
+				beg: base.basketEntry[i],
+				end: base.basketEntry[i+1],
+			}
 		}
 	}