go/arrow/array: implement Stringer for Binary array

Author: sbinet

go/arrow/array/binary.go

@@ -17,6 +17,8 @@
 package array
 
 import (
+	"fmt"
+	"strings"
 	"unsafe"
 
 	"github.com/apache/arrow/go/arrow"
@@ -80,6 +82,24 @@ func (a *Binary) ValueBytes() []byte {
 	return a.valueBytes[a.valueOffsets[beg]:a.valueOffsets[end]]
 }
 
+func (a *Binary) String() string {
+	o := new(strings.Builder)
+	o.WriteString("[")
+	for i := 0; i < a.Len(); i++ {
+		if i > 0 {
+			o.WriteString(" ")
+		}
+		switch {
+		case a.IsNull(i):
+			o.WriteString("(null)")
+		default:
+			fmt.Fprintf(o, "%q", a.ValueString(i))
+		}
+	}
+	o.WriteString("]")
+	return o.String()
+}
+
 func (a *Binary) setData(data *Data) {
 	if len(data.buffers) != 3 {
 		panic("len(data.buffers) != 3")

go/arrow/array/binary_test.go

@@ -405,3 +405,26 @@ func TestBinaryValueBytes(t *testing.T) {
 
 	assert.Equal(t, []byte{'h', 'i', 'j', 'k', 'l', 'm', 'o', 'p', 'q'}, slice.ValueBytes())
 }
+
+func TestBinaryStringer(t *testing.T) {
+	mem := memory.NewCheckedAllocator(memory.NewGoAllocator())
+	defer mem.AssertSize(t, 0)
+
+	values := []string{"a", "bc", "", "é", "", "hijk", "lm", "", "opq", "", "tu"}
+	valids := []bool{true, true, false, true, false, true, true, true, true, false, true}
+
+	b := NewBinaryBuilder(mem, arrow.BinaryTypes.Binary)
+	defer b.Release()
+
+	b.AppendStringValues(values, valids)
+
+	arr := b.NewArray().(*Binary)
+	defer arr.Release()
+
+	got := arr.String()
+	want := `["a" "bc" (null) "é" (null) "hijk" "lm" "" "opq" (null) "tu"]`
+
+	if got != want {
+		t.Fatalf("invalid stringer:\ngot= %s\nwant=%s\n", got, want)
+	}
+}