add support for negative indices in Slice(), with tests

README.md

@@ -24,8 +24,9 @@ To run benchmarks, run this command in goquery's source directory:
 
 ## Changelog
 
-*    **v0.1.0** : Initial release. See [TODOs](#a1) for a list of upcoming features.
+*    **v0.2.0** : Add support for negative indices in Slice(). *Upcoming* : add jQuery's Closest() method.
 *    **v0.1.1** : Add benchmarks to use as baseline for refactorings, refactor Next...() and Prev...() methods to use the new html package's linked list features (Next/PrevSibling, FirstChild). Good performance boost (40+% in some cases).
+*    **v0.1.0** : Initial release. See [TODOs](#a1) for a list of upcoming features.
 
 ## API
 
@@ -93,7 +94,6 @@ Taken from example_test.go:
 <a name="a1" />
 
 *    Add jQuery's `Closest()`? Other missing functions?
-*    Support negative indices in `Slice()`, like jQuery.
 
 ## License
 

array.go

@@ -30,7 +30,12 @@ func (this *Selection) Eq(index int) *Selection {
 // Slice() reduces the set of matched elements to a subset specified by a range
 // of indices. At the moment, negative indices are not supported.
 func (this *Selection) Slice(start int, end int) *Selection {
-	// TODO : Negative indices, like jQuery
+	if start < 0 {
+		start += len(this.Nodes)
+	}
+	if end < 0 {
+		end += len(this.Nodes)
+	}
 	return pushStack(this, this.Nodes[start:end])
 }
 

array_test.go

@@ -70,6 +70,31 @@ func TestSliceOutOfBounds(t *testing.T) {
 	Doc().Root.Find(".pvk-content").Slice(2, 12)
 }
 
+func TestNegativeSliceStart(t *testing.T) {
+	sel := Doc().Root.Find(".container-fluid").Slice(-2, 3)
+	AssertLength(t, sel.Nodes, 1)
+	AssertSelectionIs(t, sel.Eq(0), "#cf3")
+}
+
+func TestNegativeSliceEnd(t *testing.T) {
+	sel := Doc().Root.Find(".container-fluid").Slice(1, -1)
+	AssertLength(t, sel.Nodes, 2)
+	AssertSelectionIs(t, sel.Eq(0), "#cf2")
+	AssertSelectionIs(t, sel.Eq(1), "#cf3")
+}
+
+func TestNegativeSliceBoth(t *testing.T) {
+	sel := Doc().Root.Find(".container-fluid").Slice(-3, -1)
+	AssertLength(t, sel.Nodes, 2)
+	AssertSelectionIs(t, sel.Eq(0), "#cf2")
+	AssertSelectionIs(t, sel.Eq(1), "#cf3")
+}
+
+func TestNegativeSliceOutOfBounds(t *testing.T) {
+	defer AssertPanic(t)
+	Doc().Root.Find(".container-fluid").Slice(-12, -7)
+}
+
 func TestSliceRollback(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content")
 	sel2 := sel.Slice(0, 2).End()