From a882ddeb9a89ea1aaf7194b80424959eb2d2d7f0 Mon Sep 17 00:00:00 2001
From: Sebastien Binet <binet@cern.ch>
Date: Fri, 11 Sep 2020 16:16:51 +0200
Subject: [PATCH] groot/rbytes: export r/w std::vector<std::string>

---
 groot/rbytes/rbuffer.go | 15 +++++++++++++++
 groot/rbytes/rw_test.go | 25 +++++++++++++++++++++++++
 groot/rbytes/wbuffer.go | 22 ++++++++++++++++++++++
 3 files changed, 62 insertions(+)

diff --git a/groot/rbytes/rbuffer.go b/groot/rbytes/rbuffer.go
index 10fa1367b..ad0b4cc2d 100644
--- a/groot/rbytes/rbuffer.go
+++ b/groot/rbytes/rbuffer.go
@@ -456,6 +456,21 @@ func (r *RBuffer) ReadArrayString(arr []string) {
 	}
 }
 
+func (r *RBuffer) ReadStdVectorStrs(sli *[]string) {
+	if r.err != nil {
+		return
+	}
+	const typename = "vector<string>"
+	beg := r.Pos()
+	_ /*vers*/, pos, bcnt := r.ReadVersion(typename)
+	n := int(r.ReadI32())
+	*sli = ResizeStr(*sli, n)
+	for i := range *sli {
+		(*sli)[i] = r.ReadString()
+	}
+	r.CheckByteCount(pos, bcnt, beg, typename)
+}
+
 func (r *RBuffer) ReadVersion(class string) (vers int16, pos, n int32) {
 	if r.err != nil {
 		return
diff --git a/groot/rbytes/rw_test.go b/groot/rbytes/rw_test.go
index 5e41a11f7..086124a2a 100644
--- a/groot/rbytes/rw_test.go
+++ b/groot/rbytes/rw_test.go
@@ -6,6 +6,7 @@ package rbytes_test
 
 import (
 	"reflect"
+	"strings"
 	"testing"
 
 	"go-hep.org/x/hep/groot/rbase"
@@ -88,6 +89,30 @@ func TestRWStrings(t *testing.T) {
 	}
 }
 
+func TestRWStdVecStrings(t *testing.T) {
+	want := [][]string{
+		{"", "x", "", "xx", "", "xxx"},
+		{"x", "", "xx", "", "xxx"},
+		{"", "x", "", "xx", "", "xxx"},
+		{"x", "", "xx", "", "xxx", strings.Repeat("1!", 256)},
+	}
+	wbuf := rbytes.NewWBuffer(nil, nil, 0, nil)
+	for i, str := range want {
+		wbuf.WriteStdVectorStrs(str)
+		if err := wbuf.Err(); err != nil {
+			t.Errorf("could not write string #%d: %+v", i, err)
+		}
+	}
+	rbuf := rbytes.NewRBuffer(wbuf.Bytes(), nil, 0, nil)
+	for i := range want {
+		var got []string
+		rbuf.ReadStdVectorStrs(&got)
+		if got, want := got, want[i]; !reflect.DeepEqual(got, want) {
+			t.Errorf("invalid string at %d: got=%q, want=%q", i, got, want)
+		}
+	}
+}
+
 func TestRWFloat16(t *testing.T) {
 	makeElm := func(title string) rbytes.StreamerElement {
 		elm := rdict.Element{
diff --git a/groot/rbytes/wbuffer.go b/groot/rbytes/wbuffer.go
index f7df23736..03026105a 100644
--- a/groot/rbytes/wbuffer.go
+++ b/groot/rbytes/wbuffer.go
@@ -730,6 +730,28 @@ func (w *WBuffer) WriteFastArrayString(v []string) {
 	}
 }
 
+func (w *WBuffer) WriteStdVectorStrs(v []string) {
+	const typename = "vector<string>"
+	if w.err != nil {
+		return
+	}
+	var (
+		pos = w.WriteVersion(rvers.StreamerInfo)
+	)
+	w.WriteI32(int32(len(v)))
+
+	n := 0
+	for _, v := range v {
+		n += w.strlen(v)
+	}
+	w.w.grow(n)
+
+	for _, v := range v {
+		w.writeString(v)
+	}
+	_, _ = w.SetByteCount(pos, typename)
+}
+
 var (
 	_ StreamerInfoContext = (*WBuffer)(nil)
 )