cmd,groot: remove rtree.{Tree,}Scanner

Updates #773.

cmd/npy2root/main_test.go

@@ -5,6 +5,7 @@
 package main
 
 import (
+	"fmt"
 	"io/ioutil"
 	"math"
 	"os"
@@ -280,21 +281,16 @@ func TestConvert(t *testing.T) {
 
 			tree := obj.(rtree.Tree)
 			rvars := rtree.NewReadVars(tree)
-			scan, err := rtree.NewScannerVars(tree, rvars...)
+			r, err := rtree.NewReader(tree, rvars)
 			if err != nil {
-				t.Fatalf("could not create tree scanner: %+v", err)
+				t.Fatalf("could not create tree reader: %+v", err)
 			}
-			defer scan.Close()
+			defer r.Close()
 
 			want := reflect.ValueOf(tc.want)
 			n := 0
-			for scan.Next() {
-				err := scan.Scan()
-				if err != nil {
-					t.Fatalf("could not read entry %d: %+v", scan.Entry(), err)
-				}
-
-				i := int(scan.Entry())
+			err = r.Read(func(ctx rtree.RCtx) error {
+				i := int(ctx.Entry)
 				want := want.Index(i).Interface()
 				got := reflect.ValueOf(rvars[0].Value).Elem().Interface()
 				ok := false
@@ -316,9 +312,13 @@ func TestConvert(t *testing.T) {
 				}
 
 				if !ok {
-					t.Fatalf("invalid value for entry %d:\ngot= %v\nwant=%v", scan.Entry(), got, want)
+					return fmt.Errorf("invalid value for entry %d:\ngot= %v\nwant=%v", ctx.Entry, got, want)
 				}
 				n++
+				return nil
+			})
+			if err != nil {
+				t.Fatalf("could not read tree: %+v", err)
 			}
 
 			if got, want := n, want.Len(); got != want {

cmd/root2csv/main.go

@@ -116,20 +116,20 @@ func process(oname, fname, tname string) error {
 	}
 	log.Printf("scanning leaves... [done]")
 
-	sc, err := rtree.NewTreeScannerVars(tree, nt.args...)
+	r, err := rtree.NewReader(tree, nt.args)
 	if err != nil {
-		return fmt.Errorf("could not create tree scanner: %w", err)
+		return fmt.Errorf("could not create tree reader: %w", err)
 	}
-	defer sc.Close()
+	defer r.Close()
 
 	nrows := 0
-	for sc.Next() {
-		err = sc.Scan(nt.vars...)
-		if err != nil {
-			return fmt.Errorf("could not scan entry %d: %w", nrows, err)
-		}
+	err = r.Read(func(ctx rtree.RCtx) error {
 		nt.fill()
 		nrows++
+		return nil
+	})
+	if err != nil {
+		return fmt.Errorf("could not read tree: %w", err)
 	}
 
 	tbl, err := csvutil.Create(oname)

cmd/root2fits/main.go

@@ -122,21 +122,22 @@ func process(oname, tname, fname string) error {
 	for i, rvar := range rvars {
 		wvars[i] = rvar.Value
 	}
-	scan, err := rtree.NewScannerVars(tree, rvars...)
+
+	r, err := rtree.NewReader(tree, rvars)
 	if err != nil {
-		return fmt.Errorf("could not create ROOT scanner: %w", err)
+		return fmt.Errorf("could not create ROOT reader: %w", err)
 	}
-	defer scan.Close()
+	defer r.Close()
 
-	for scan.Next() {
-		err = scan.Scan()
-		if err != nil {
-			return fmt.Errorf("could not read entry %d from ROOT tree: %w", scan.Entry(), err)
-		}
+	err = r.Read(func(ctx rtree.RCtx) error {
 		err = tbl.Write(wvars...)
 		if err != nil {
-			return fmt.Errorf("could not write entry %d to FITS table: %w", scan.Entry(), err)
+			return fmt.Errorf("could not write entry %d to FITS table: %w", ctx.Entry, err)
 		}
+		return nil
+	})
+	if err != nil {
+		return fmt.Errorf("could not read input ROOT file: %w", err)
 	}
 
 	err = fits.Write(tbl)