Refactor method AddRange and DeleteRange

Author: b97tsk

intervalset.go

@@ -1,7 +1,10 @@
 // Package intervals is a library for manipulating sets of intervals.
 package intervals
 
-import "sort"
+import (
+	"slices"
+	"sort"
+)
 
 // Elem is the type set containing all supported element types.
 type Elem[E any] interface {
@@ -170,19 +173,13 @@ func (x *Set[E]) AddRange(lo, hi E) {
 		}
 	}
 
-	if i == j { // Case 3 (where lo and hi overlap with each other).
-		if lo.Compare(hi) < 0 {
-			s = append(s, Interval[E]{})
-			copy(s[i+1:], s[i:])
-			s[i] = Interval[E]{lo, hi}
-			*x = s
+	if i == j { // Case 3 (where lo and hi overlap).
+		if lo.Compare(hi) >= 0 { // Get rid of the devil first.
+			return
 		}
-
-		return
 	}
 
-	s[i] = Interval[E]{lo, hi}
-	s = append(s[:i+1], s[j:]...)
+	s = slices.Replace(s, i, j, Range(lo, hi))
 	*x = s
 }
 
@@ -232,43 +229,24 @@ func (x *Set[E]) DeleteRange(lo, hi E) {
 	}
 
 	if i == j-1 { // Case 4.
-		if r := &s[i]; r.Low.Compare(lo) < 0 {
-			if r.High.Compare(hi) > 0 {
-				if lo.Compare(hi) < 0 {
-					s = append(s, Interval[E]{})
-					copy(s[j:], s[i:])
-					s[i].High = lo
-					s[j].Low = hi
-					*x = s
-				}
-			} else {
-				r.High = lo
-			}
-		} else {
-			if r.High.Compare(hi) > 0 {
-				r.Low = hi
-			} else {
-				s = append(s[:i], s[j:]...)
-				*x = s
-			}
+		if lo.Compare(hi) >= 0 { // Get rid of the devil first.
+			return
 		}
-
-		return
 	}
 
-	// Case 5.
+	// Case 4 and 5.
+
+	v := make([]Interval[E], 0, 2)
 
 	if r := &s[i]; r.Low.Compare(lo) < 0 {
-		r.High = lo
-		i++
+		v = append(v, Range(r.Low, lo))
 	}
 
 	if r := &s[j-1]; r.High.Compare(hi) > 0 {
-		r.Low = hi
-		j--
+		v = append(v, Range(hi, r.High))
 	}
 
-	s = append(s[:i], s[j:]...)
+	s = slices.Replace(s, i, j, v...)
 	*x = s
 }
 

intervalset_test.go

@@ -13,6 +13,10 @@ func TestCreation(t *testing.T) {
 	testCases := []struct {
 		Actual, Expected Set[E]
 	}{
+		{
+			One[E](1).Set(),
+			Set[E]{{1, 2}},
+		},
 		{
 			Range[E](1, 5).Set(),
 			Set[E]{{1, 5}},
@@ -67,36 +71,28 @@ func TestAdd(t *testing.T) {
 		Actual, Expected Set[E]
 	}{
 		{
-			add(Set[E]{{1, 4}, {9, 12}}, Range[E](5, 8)),
-			Set[E]{{1, 4}, {5, 8}, {9, 12}},
-		},
-		{
-			add(Set[E]{{1, 4}, {9, 12}}, One[E](6)),
-			Set[E]{{1, 4}, {6, 7}, {9, 12}},
-		},
-		{
-			add(Set[E]{{1, 4}, {9, 12}}, Range[E](4, 8)),
-			Set[E]{{1, 8}, {9, 12}},
+			add(Set[E]{{1, 5}, {11, 15}}, Range[E](5, 11)),
+			Set[E]{{1, 15}},
 		},
 		{
-			add(Set[E]{{1, 4}, {9, 12}}, Range[E](5, 9)),
-			Set[E]{{1, 4}, {5, 12}},
+			add(Set[E]{{1, 5}, {11, 15}}, Range[E](5, 9)),
+			Set[E]{{1, 9}, {11, 15}},
 		},
 		{
-			add(Set[E]{{1, 4}, {9, 12}}, Range[E](4, 9)),
-			Set[E]{{1, 12}},
+			add(Set[E]{{1, 5}, {11, 15}}, Range[E](7, 11)),
+			Set[E]{{1, 5}, {7, 15}},
 		},
 		{
-			add(Set[E]{{1, 4}, {9, 12}}, One[E](10)),
-			Set[E]{{1, 4}, {9, 12}},
+			add(Set[E]{{1, 5}, {11, 15}}, Range[E](7, 9)),
+			Set[E]{{1, 5}, {7, 9}, {11, 15}},
 		},
 		{
-			add(Set[E]{{1, 4}, {9, 12}}, Range[E](9, 12)),
-			Set[E]{{1, 4}, {9, 12}},
+			add(Set[E]{{1, 5}, {11, 15}}, Range[E](9, 7)),
+			Set[E]{{1, 5}, {11, 15}},
 		},
 		{
-			add(Set[E]{{1, 4}, {9, 12}}, Range[E](12, 9)),
-			Set[E]{{1, 4}, {9, 12}},
+			add(Set[E]{{1, 5}, {11, 15}}, Range[E](15, 11)),
+			Set[E]{{1, 5}, {11, 15}},
 		},
 	}
 
@@ -120,44 +116,28 @@ func TestDelete(t *testing.T) {
 		Actual, Expected Set[E]
 	}{
 		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](7, 10)),
-			Set[E]{{1, 4}, {13, 16}},
-		},
-		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](7, 9)),
-			Set[E]{{1, 4}, {9, 10}, {13, 16}},
-		},
-		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](8, 10)),
-			Set[E]{{1, 4}, {7, 8}, {13, 16}},
-		},
-		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, One[E](8)),
-			Set[E]{{1, 4}, {7, 8}, {9, 10}, {13, 16}},
-		},
-		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](1, 16)),
-			Set[E]{},
+			del(Set[E]{{1, 3}, {5, 11}, {13, 15}}, Range[E](5, 11)),
+			Set[E]{{1, 3}, {13, 15}},
 		},
 		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](1, 15)),
-			Set[E]{{15, 16}},
+			del(Set[E]{{1, 3}, {5, 11}, {13, 15}}, Range[E](5, 9)),
+			Set[E]{{1, 3}, {9, 11}, {13, 15}},
 		},
 		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](2, 16)),
-			Set[E]{{1, 2}},
+			del(Set[E]{{1, 3}, {5, 11}, {13, 15}}, Range[E](7, 11)),
+			Set[E]{{1, 3}, {5, 7}, {13, 15}},
 		},
 		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, One[E](5)),
-			Set[E]{{1, 4}, {7, 10}, {13, 16}},
+			del(Set[E]{{1, 3}, {5, 11}, {13, 15}}, Range[E](7, 9)),
+			Set[E]{{1, 3}, {5, 7}, {9, 11}, {13, 15}},
 		},
 		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](4, 7)),
-			Set[E]{{1, 4}, {7, 10}, {13, 16}},
+			del(Set[E]{{1, 3}, {5, 11}, {13, 15}}, Range[E](9, 7)),
+			Set[E]{{1, 3}, {5, 11}, {13, 15}},
 		},
 		{
-			del(Set[E]{{1, 4}, {7, 10}, {13, 16}}, Range[E](7, 4)),
-			Set[E]{{1, 4}, {7, 10}, {13, 16}},
+			del(Set[E]{{1, 3}, {5, 11}, {13, 15}}, Range[E](5, 3)),
+			Set[E]{{1, 3}, {5, 11}, {13, 15}},
 		},
 	}