manipulation: Add Prepend*()

Looks like I missed yet another manipulation function.

manipulation.go

@@ -162,6 +162,45 @@ func (s *Selection) Empty() *Selection {
 	return pushStack(s, nodes)
 }
 
+// Prepend prepends the elements specified by the selector to each element in
+// the set of matched elements, following the same rules as Append.
+func (s *Selection) Prepend(selector string) *Selection {
+	return s.PrependMatcher(cascadia.MustCompile(selector))
+}
+
+// PrependMatcher prepends the elements specified by the matcher to each
+// element in the set of matched elements.
+//
+// This follows the same rules as Selection.Append.
+func (s *Selection) PrependMatcher(m Matcher) *Selection {
+	return s.PrependNodes(m.MatchAll(s.document.rootNode)...)
+}
+
+// PrependSelection prepends the elements in the selection to each element in
+// the set of matched elements.
+//
+// This follows the same rules as Selection.Append.
+func (s *Selection) PrependSelection(sel *Selection) *Selection {
+	return s.PrependNodes(sel.Nodes...)
+}
+
+// PrependHtml parses the html and prepends it to the set of matched elements.
+func (s *Selection) PrependHtml(html string) *Selection {
+	return s.PrependNodes(parseHtml(html)...)
+}
+
+// PrependNodes prepends the specified nodes to each node in the set of
+// matched elements.
+//
+// This follows the same rules as Selection.Append.
+func (s *Selection) PrependNodes(ns ...*html.Node) *Selection {
+	return s.manipulateNodes(ns, true, func(sn *html.Node, n *html.Node) {
+		// sn.FirstChild may be nil, in which case this functions like
+		// sn.AppendChild()
+		sn.InsertBefore(n, sn.FirstChild)
+	})
+}
+
 // Remove removes the set of matched elements from the document.
 // It returns the same selection, now consisting of nodes not in the document.
 func (s *Selection) Remove() *Selection {

manipulation_test.go

@@ -160,6 +160,64 @@ func TestEmpty(t *testing.T) {
 	printSel(t, doc.Selection)
 }
 
+func TestPrepend(t *testing.T) {
+	doc := Doc2Clone()
+	doc.Find("#main").Prepend("#nf6")
+
+	assertLength(t, doc.Find("#foot #nf6").Nodes, 0)
+	assertLength(t, doc.Find("#main #nf6:first-child").Nodes, 1)
+	printSel(t, doc.Selection)
+}
+
+func TestPrependBody(t *testing.T) {
+	doc := Doc2Clone()
+	doc.Find("body").Prepend("#nf6")
+
+	assertLength(t, doc.Find("#foot #nf6").Nodes, 0)
+	assertLength(t, doc.Find("#main #nf6").Nodes, 0)
+	assertLength(t, doc.Find("body > #nf6:first-child").Nodes, 1)
+	printSel(t, doc.Selection)
+}
+
+func TestPrependSelection(t *testing.T) {
+	doc := Doc2Clone()
+	doc.Find("#main").PrependSelection(doc.Find("#nf1, #nf2"))
+
+	assertLength(t, doc.Find("#foot #nf1").Nodes, 0)
+	assertLength(t, doc.Find("#foot #nf2").Nodes, 0)
+	assertLength(t, doc.Find("#main #nf1:first-child").Nodes, 1)
+	assertLength(t, doc.Find("#main #nf2:nth-child(2)").Nodes, 1)
+	printSel(t, doc.Selection)
+}
+
+func TestPrependSelectionExisting(t *testing.T) {
+	doc := Doc2Clone()
+	doc.Find("#main").PrependSelection(doc.Find("#n5, #n6"))
+
+	assertClass(t, doc.Find("#main :nth-child(1)"), "five")
+	assertClass(t, doc.Find("#main :nth-child(2)"), "six")
+	assertClass(t, doc.Find("#main :nth-child(5)"), "three")
+	assertClass(t, doc.Find("#main :nth-child(6)"), "four")
+	printSel(t, doc.Selection)
+}
+
+func TestPrependClone(t *testing.T) {
+	doc := Doc2Clone()
+	doc.Find("#n1").PrependSelection(doc.Find("#nf1").Clone())
+
+	assertLength(t, doc.Find("#foot #nf1:first-child").Nodes, 1)
+	assertLength(t, doc.Find("#main #nf1:first-child").Nodes, 1)
+	printSel(t, doc.Selection)
+}
+
+func TestPrependHtml(t *testing.T) {
+	doc := Doc2Clone()
+	doc.Find("div").PrependHtml("<strong>new node</strong>")
+
+	assertLength(t, doc.Find("strong:first-child").Nodes, 14)
+	printSel(t, doc.Selection)
+}
+
 func TestRemove(t *testing.T) {
 	doc := Doc2Clone()
 	doc.Find("#nf1").Remove()