Add String(), FromString() methods

Author: cyradin

README.md

@@ -32,5 +32,12 @@ func main() {
         fmt.PrintLn(n)
         return true
     })
+
+    // to string, from string
+    var b3 bitmap.Bitmap
+    b3.Set(1)
+    b3.Set(100)
+    b3.String() // "2|68719476736"
+    b4, err := bitmap.FromString("2|68719476736")
 }
 ```

bitmap.go

@@ -1,6 +1,10 @@
 package bitmap
 
-import "math/bits"
+import (
+	"math/bits"
+	"strconv"
+	"strings"
+)
 
 type Bitmap []uint64
 
@@ -97,6 +101,36 @@ func (b *Bitmap) Range(f func(n uint32) bool) {
 	}
 }
 
+func (b *Bitmap) String() string {
+	var sb strings.Builder
+
+	for i := range *b {
+		sb.WriteString(strconv.FormatUint((*b)[i], 10))
+		if i != len(*b)-1 {
+			sb.WriteString("|")
+		}
+	}
+
+	return sb.String()
+}
+
+func FromString(str string) (Bitmap, error) {
+	if str == "" {
+		return Bitmap{}, nil
+	}
+
+	nums := strings.Split(str, "|")
+	result := make(Bitmap, 0, len(nums))
+	for _, num := range nums {
+		v, err := strconv.ParseUint(num, 10, 64)
+		if err != nil {
+			return nil, err
+		}
+		result = append(result, v)
+	}
+	return result, nil
+}
+
 func (b *Bitmap) grow(length uint32) {
 	if length+1 > uint32(len(*b)) {
 		*b = append(*b, make(Bitmap, length+1-uint32(len(*b)))...)

bitmap_test.go

@@ -4,7 +4,6 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 )
 
 func Benchmark_Bitmap_Set(b *testing.B) {
@@ -168,5 +167,40 @@ func Test_Bitmap_Range(t *testing.T) {
 		return true
 	})
 
-	require.Equal(t, []uint32{0, 1, 2, 1000}, items)
+	assert.Equal(t, []uint32{0, 1, 2, 1000}, items)
+}
+
+func Benchmark_Bitmap_String(b *testing.B) {
+	bm := Bitmap{0, 5, 1000}
+	for i := 0; i < b.N; i++ {
+		_ = bm.String()
+	}
+}
+
+func Test_Bitmap_String(t *testing.T) {
+	b := Bitmap{}
+	assert.Equal(t, "", b.String())
+
+	b = Bitmap{0, 5, 100}
+	assert.Equal(t, "0|5|100", b.String())
+}
+
+func Test_FromString(t *testing.T) {
+	t.Run("must return error if unable to parse the string", func(t *testing.T) {
+		_, err := FromString("qwe")
+		assert.Error(t, err)
+	})
+	t.Run("must parse the string correctly", func(t *testing.T) {
+		v, err := FromString("")
+		assert.Nil(t, err)
+		assert.Equal(t, Bitmap{}, v)
+
+		v, err = FromString("0")
+		assert.Nil(t, err)
+		assert.Equal(t, Bitmap{0}, v)
+
+		v, err = FromString("0|5")
+		assert.Nil(t, err)
+		assert.Equal(t, Bitmap{0, 5}, v)
+	})
 }