Close #7 - add Set.New(size) constuctor

set.go

@@ -5,8 +5,17 @@ import (
 )
 
 // Set defines a unique set of IPv4 addresses using a simple []uint32
+//
+// Since Set is a alias of []unit32, one can use
+// `make(Set, length, capacity)` or use the NewSet constructor
+//
 type Set []uint32
 
+// NewSet creates a Set with a given initial capacity.
+func NewSet(capacity int) Set {
+	return make(Set, 0, capacity)
+}
+
 // Len returns a length, part of the Sort.Interface
 func (m Set) Len() int {
 	return len(m)
@@ -76,26 +85,6 @@ func (m *Set) AddAll(ipv4dots []string) bool {
 	return true
 }
 
-func (m *Set) sort() {
-	in := *m
-	sort.Sort(in)
-
-	// inplace sort
-	// https://github.com/golang/go/wiki/SliceTricks#in-place-deduplicate-comparable
-	j := 0
-	for i := 1; i < len(in); i++ {
-		if in[j] == in[i] {
-			continue
-		}
-		j++
-		// preserve the original data
-		// in[i], in[j] = in[j], in[i]
-		// only set what is required
-		in[j] = in[i]
-	}
-	in = in[:j+1]
-}
-
 // Valid return true if the internal storage is in sorted form and unique
 func (m Set) Valid() bool {
 	if len(m) == 0 {
@@ -111,10 +100,31 @@ func (m Set) Valid() bool {
 	return true
 }
 
+// ToDots returns the IP set as a list of dotted-notation strings
 func (m Set) ToDots() []string {
 	out := make([]string, len(m))
 	for i, val := range m {
 		out[i] = ToDots(val)
 	}
 	return out
 }
+
+func (m *Set) sort() {
+	in := *m
+	sort.Sort(in)
+
+	// inplace sort
+	// https://github.com/golang/go/wiki/SliceTricks#in-place-deduplicate-comparable
+	j := 0
+	for i := 1; i < len(in); i++ {
+		if in[j] == in[i] {
+			continue
+		}
+		j++
+		// preserve the original data
+		// in[i], in[j] = in[j], in[i]
+		// only set what is required
+		in[j] = in[i]
+	}
+	in = in[:j+1]
+}

set_test.go

@@ -86,7 +86,7 @@ func TestAdd(t *testing.T) {
 }
 
 func TestAddAll(t *testing.T) {
-	s := Set{}
+	s := NewSet(2)
 	s.AddAll([]string{"127.0.0.1", "10.0.0.1"})
 	if !s.Valid() {
 		t.Fatalf("AddAll is not valid")