Add element Tail and SetTail methods.

Tail returns the character data immediately following an
element's end tag. SetTail modifies it.

SetText now replaces runs of character data tokens (CDATA
or text) with a single character data token. SetCData works
similarly.

The Token interface offers a new Index method, which
returns the index of the token in its parent's child list.

Added element RemoveChildAt and InsertChildAt methods. Both
methods take an index as a parameter.

Deprecated the element InsertChild method in favor of
InsertChildAt.

3 files changed, 484 insertions, 66 deletions

diff --git a/etree.go b/etree.go
index 5685e0e..aad48df 100644
--- a/etree.go
+++ b/etree.go
@@ -86,8 +86,10 @@ func newWriteSettings() WriteSettings {
 // Comment, Directive, or ProcInst.
 type Token interface {
 	Parent() *Element
+	Index() int
 	dup(parent *Element) Token
 	setParent(parent *Element)
+	setIndex(index int)
 	writeTo(w *bufio.Writer, s *WriteSettings)
 }
 
@@ -107,6 +109,7 @@ type Element struct {
 	Attr       []Attr   // key-value attribute pairs
 	Child      []Token  // child tokens (elements, comments, etc.)
 	parent     *Element // parent element
+	index      int      // token index in parent's children
 }
 
 // An Attr represents a key-value attribute of an XML element.
@@ -131,6 +134,7 @@ const (
 type CharData struct {
 	Data   string
 	parent *Element
+	index  int
 	flags  charDataFlags
 }
 
@@ -138,12 +142,14 @@ type CharData struct {
 type Comment struct {
 	Data   string
 	parent *Element
+	index  int
 }
 
 // A Directive represents an XML directive.
 type Directive struct {
 	Data   string
 	parent *Element
+	index  int
 }
 
 // A ProcInst represents an XML processing instruction.
@@ -151,6 +157,7 @@ type ProcInst struct {
 	Target string
 	Inst   string
 	parent *Element
+	index  int
 }
 
 // NewDocument creates an XML document without a root element.
@@ -187,16 +194,23 @@ func (d *Document) SetRoot(e *Element) {
 	if e.parent != nil {
 		e.parent.RemoveChild(e)
 	}
-	e.setParent(&d.Element)
 
-	for i, t := range d.Child {
+	p := &d.Element
+	e.setParent(p)
+
+	// If there is already a root element, replace it.
+	for i, t := range p.Child {
 		if _, ok := t.(*Element); ok {
 			t.setParent(nil)
-			d.Child[i] = e
+			t.setIndex(-1)
+			p.Child[i] = e
+			e.setIndex(i)
 			return
 		}
 	}
-	d.Child = append(d.Child, e)
+
+	// No existing root element, so add it.
+	p.addChild(e)
 }
 
 // ReadFrom reads XML from the reader r into the document d. It returns the
@@ -335,7 +349,7 @@ func (e *Element) Copy() *Element {
 	return e.dup(parent).(*Element)
 }
 
-// Text returns the characters immediately following the element's opening
+// Text returns all character data immediately following the element's opening
 // tag.
 func (e *Element) Text() string {
 	if len(e.Child) == 0 {
@@ -357,28 +371,110 @@ func (e *Element) Text() string {
 	return text
 }
 
-// SetText replaces an element's subsidiary CharData text with a new string.
+// SetText replaces all character data immediately following an element's
+// opening tag with the requested string.
 func (e *Element) SetText(text string) {
-	e.setCharData(text, 0)
+	e.replaceText(0, text, 0)
 }
 
-// SetCData replaces an element's subsidiary CharData text with a new string
-// encoded into a CDATA section.
+// SetCData replaces all character data immediately following an element's
+// opening tag with a CDATA section.
 func (e *Element) SetCData(text string) {
-	e.setCharData(text, cdataFlag)
+	e.replaceText(0, text, cdataFlag)
 }
 
-// setCharData is a helper function used by SetText and SetCData.
-func (e *Element) setCharData(text string, flags charDataFlags) {
-	if len(e.Child) > 0 {
-		if cd, ok := e.Child[0].(*CharData); ok {
+// Tail returns all character data immediately following the element's end
+// tag.
+func (e *Element) Tail() string {
+	if e.Parent() == nil {
+		return ""
+	}
+
+	p := e.Parent()
+	i := e.Index()
+
+	text := ""
+	for _, ch := range p.Child[i+1:] {
+		if cd, ok := ch.(*CharData); ok {
+			if text == "" {
+				text = cd.Data
+			} else {
+				text = text + cd.Data
+			}
+		} else {
+			break
+		}
+	}
+	return text
+}
+
+// SetTail replaces all character data immediately following the element's end
+// tag with the requested string.
+func (e *Element) SetTail(text string) {
+	if e.Parent() == nil {
+		return
+	}
+
+	p := e.Parent()
+	p.replaceText(e.Index()+1, text, 0)
+}
+
+// replaceText is a helper function that replaces a series of chardata tokens
+// starting at index i with the requested text.
+func (e *Element) replaceText(i int, text string, flags charDataFlags) {
+	end := e.findTermCharDataIndex(i)
+
+	switch {
+	case end == i:
+		if text != "" {
+			// insert a new chardata token at index i
+			cd := newCharData(text, flags, nil)
+			e.InsertChildAt(i, cd)
+		}
+
+	case end == i+1:
+		if text == "" {
+			// remove the chardata token at index i
+			e.RemoveChildAt(i)
+		} else {
+			// replace the first and only character token at index i
+			cd := e.Child[i].(*CharData)
 			cd.Data, cd.flags = text, flags
-			return
+		}
+
+	default:
+		if text == "" {
+			// remove all chardata tokens starting from index i
+			copy(e.Child[i:], e.Child[end:])
+			removed := end - i
+			e.Child = e.Child[:len(e.Child)-removed]
+			for j := i; j < len(e.Child); j++ {
+				e.Child[j].setIndex(j)
+			}
+		} else {
+			// replace the first chardata token at index i and remove all
+			// subsequent chardata tokens
+			cd := e.Child[i].(*CharData)
+			cd.Data, cd.flags = text, flags
+			copy(e.Child[i+1:], e.Child[end:])
+			removed := end - (i + 1)
+			e.Child = e.Child[:len(e.Child)-removed]
+			for j := i + 1; j < len(e.Child); j++ {
+				e.Child[j].setIndex(j)
+			}
+		}
+	}
+}
+
+// findTermCharDataIndex finds the index of the first child token that isn't
+// a CharData token. It starts from the requested start index.
+func (e *Element) findTermCharDataIndex(start int) int {
+	for i := start; i < len(e.Child); i++ {
+		if _, ok := e.Child[i].(*CharData); !ok {
+			return i
 		}
 	}
-	cd := newCharData(text, flags, e)
-	copy(e.Child[1:], e.Child[0:])
-	e.Child[0] = cd
+	return len(e.Child)
 }
 
 // CreateElement creates an element with the specified tag and adds it as the
@@ -396,43 +492,93 @@ func (e *Element) AddChild(t Token) {
 	if t.Parent() != nil {
 		t.Parent().RemoveChild(t)
 	}
+
 	t.setParent(e)
 	e.addChild(t)
 }
 
 // InsertChild inserts the token t before e's existing child token ex. If ex
-// is nil (or if ex is not a child of e), then t is added to the end of e's
-// child token list. If token t was already the child of another element, it
-// is first removed from its current parent element.
+// is nil or ex is not a child of e, then t is added to the end of e's child
+// token list. If token t was already the child of another element, it is
+// first removed from its current parent element.
+//
+// Deprecated: InsertChild is deprecated. Use InsertChildAt instead.
 func (e *Element) InsertChild(ex Token, t Token) {
+	if ex == nil || ex.Parent() != e {
+		e.AddChild(t)
+		return
+	}
+
 	if t.Parent() != nil {
 		t.Parent().RemoveChild(t)
 	}
+
 	t.setParent(e)
 
-	for i, c := range e.Child {
-		if c == ex {
-			e.Child = append(e.Child, nil)
-			copy(e.Child[i+1:], e.Child[i:])
-			e.Child[i] = t
-			return
+	i := ex.Index()
+	e.Child = append(e.Child, nil)
+	copy(e.Child[i+1:], e.Child[i:])
+	e.Child[i] = t
+
+	for j := i; j < len(e.Child); j++ {
+		e.Child[j].setIndex(j)
+	}
+}
+
+// InsertChildAt inserts the token t into the element e's list of child tokens
+// just before the requested index. If the index is greater than or equal to
+// the length of the list of child tokens, the token t is added to the end of
+// the list.
+func (e *Element) InsertChildAt(index int, t Token) {
+	if index >= len(e.Child) {
+		e.AddChild(t)
+		return
+	}
+
+	if t.Parent() != nil {
+		if t.Parent() == e && t.Index() > index {
+			index--
 		}
+		t.Parent().RemoveChild(t)
+	}
+
+	t.setParent(e)
+
+	e.Child = append(e.Child, nil)
+	copy(e.Child[index+1:], e.Child[index:])
+	e.Child[index] = t
+
+	for j := index; j < len(e.Child); j++ {
+		e.Child[j].setIndex(j)
 	}
-	e.addChild(t)
 }
 
 // RemoveChild attempts to remove the token t from element e's list of
 // children. If the token t is a child of e, then it is returned. Otherwise,
 // nil is returned.
 func (e *Element) RemoveChild(t Token) Token {
-	for i, c := range e.Child {
-		if c == t {
-			e.Child = append(e.Child[:i], e.Child[i+1:]...)
-			c.setParent(nil)
-			return t
-		}
+	if t.Parent() != e {
+		return nil
 	}
-	return nil
+	return e.RemoveChildAt(t.Index())
+}
+
+// RemoveChildAt removes the index-th child token from the element e. The
+// removed child token is returned. If the index is out of bounds, no child is
+// removed and nil is returned.
+func (e *Element) RemoveChildAt(index int) Token {
+	if index >= len(e.Child) {
+		return nil
+	}
+
+	t := e.Child[index]
+	for j := index + 1; j < len(e.Child); j++ {
+		e.Child[j].setIndex(j - 1)
+	}
+	e.Child = append(e.Child[:index], e.Child[index+1:]...)
+	t.setIndex(-1)
+	t.setParent(nil)
+	return t
 }
 
 // ReadFrom reads XML from the reader r and stores the result as a new child
@@ -734,6 +880,7 @@ func (e *Element) stripIndent() {
 			continue
 		}
 		newChild[j] = c
+		newChild[j].setIndex(j)
 		j++
 	}
 	e.Child = newChild
@@ -763,11 +910,23 @@ func (e *Element) Parent() *Element {
 	return e.parent
 }
 
+// Index returns the index of this element within its parent element's
+// list of child tokens. If this element has no parent element, the index
+// is -1.
+func (e *Element) Index() int {
+	return e.index
+}
+
 // setParent replaces the element token's parent.
 func (e *Element) setParent(parent *Element) {
 	e.parent = parent
 }
 
+// setIndex sets the element token's index within its parent's Child slice.
+func (e *Element) setIndex(index int) {
+	e.index = index
+}
+
 // writeTo serializes the element to the writer w.
 func (e *Element) writeTo(w *bufio.Writer, s *WriteSettings) {
 	w.WriteByte('<')
@@ -809,6 +968,7 @@ func (e *Element) writeTo(w *bufio.Writer, s *WriteSettings) {
 
 // addChild adds a child token to the element e.
 func (e *Element) addChild(t Token) {
+	t.setIndex(len(e.Child))
 	e.Child = append(e.Child, t)
 }
 
@@ -912,6 +1072,7 @@ func newCharData(data string, flags charDataFlags, parent *Element) *CharData {
 	c := &CharData{
 		Data:   data,
 		parent: parent,
+		index:  -1,
 		flags:  flags,
 	}
 	if parent != nil {
@@ -968,11 +1129,24 @@ func (c *CharData) Parent() *Element {
 	return c.parent
 }
 
+// Index returns the index of this CharData token within its parent element's
+// list of child tokens. If this CharData token has no parent element, the
+// index is -1.
+func (c *CharData) Index() int {
+	return c.index
+}
+
 // setParent replaces the character data token's parent.
 func (c *CharData) setParent(parent *Element) {
 	c.parent = parent
 }
 
+// setIndex sets the CharData token's index within its parent element's Child
+// slice.
+func (c *CharData) setIndex(index int) {
+	c.index = index
+}
+
 // writeTo serializes character data to the writer.
 func (c *CharData) writeTo(w *bufio.Writer, s *WriteSettings) {
 	if c.IsCData() {
@@ -1001,6 +1175,7 @@ func newComment(comment string, parent *Element) *Comment {
 	c := &Comment{
 		Data:   comment,
 		parent: parent,
+		index:  -1,
 	}
 	if parent != nil {
 		parent.addChild(c)
@@ -1026,11 +1201,24 @@ func (c *Comment) Parent() *Element {
 	return c.parent
 }
 
+// Index returns the index of this Comment token within its parent element's
+// list of child tokens. If this Comment token has no parent element, the
+// index is -1.
+func (c *Comment) Index() int {
+	return c.index
+}
+
 // setParent replaces the comment token's parent.
 func (c *Comment) setParent(parent *Element) {
 	c.parent = parent
 }
 
+// setIndex sets the Comment token's index within its parent element's Child
+// slice.
+func (c *Comment) setIndex(index int) {
+	c.index = index
+}
+
 // writeTo serialies the comment to the writer.
 func (c *Comment) writeTo(w *bufio.Writer, s *WriteSettings) {
 	w.WriteString("<!--")
@@ -1049,6 +1237,7 @@ func newDirective(data string, parent *Element) *Directive {
 	d := &Directive{
 		Data:   data,
 		parent: parent,
+		index:  -1,
 	}
 	if parent != nil {
 		parent.addChild(d)
@@ -1076,11 +1265,24 @@ func (d *Directive) Parent() *Element {
 	return d.parent
 }
 
+// Index returns the index of this Directive token within its parent element's
+// list of child tokens. If this Directive token has no parent element, the
+// index is -1.
+func (d *Directive) Index() int {
+	return d.index
+}
+
 // setParent replaces the directive token's parent.
 func (d *Directive) setParent(parent *Element) {
 	d.parent = parent
 }
 
+// setIndex sets the Directive token's index within its parent element's Child
+// slice.
+func (d *Directive) setIndex(index int) {
+	d.index = index
+}
+
 // writeTo serializes the XML directive to the writer.
 func (d *Directive) writeTo(w *bufio.Writer, s *WriteSettings) {
 	w.WriteString("<!")
@@ -1100,6 +1302,7 @@ func newProcInst(target, inst string, parent *Element) *ProcInst {
 		Target: target,
 		Inst:   inst,
 		parent: parent,
+		index:  -1,
 	}
 	if parent != nil {
 		parent.addChild(p)
@@ -1128,11 +1331,24 @@ func (p *ProcInst) Parent() *Element {
 	return p.parent
 }
 
+// Index returns the index of this ProcInst token within its parent element's
+// list of child tokens. If this ProcInst token has no parent element, the
+// index is -1.
+func (p *ProcInst) Index() int {
+	return p.index
+}
+
 // setParent replaces the processing instruction token's parent.
 func (p *ProcInst) setParent(parent *Element) {
 	p.parent = parent
 }
 
+// setIndex sets the processing instruction token's index within its parent
+// element's Child slice.
+func (p *ProcInst) setIndex(index int) {
+	p.index = index
+}
+
 // writeTo serializes the processing instruction to the writer.
 func (p *ProcInst) writeTo(w *bufio.Writer, s *WriteSettings) {
 	w.WriteString("<?")
diff --git a/etree_test.go b/etree_test.go
index ea67843..9636c39 100644
--- a/etree_test.go
+++ b/etree_test.go
@@ -11,12 +11,52 @@ import (
 	"testing"
 )
 
-func checkEq(t *testing.T, got, want string) {
+func checkStrEq(t *testing.T, got, want string) {
+	t.Helper()
 	if got != want {
 		t.Errorf("etree: unexpected result.\nGot:\n%s\nWanted:\n%s\n", got, want)
 	}
 }
 
+func checkStrBinaryEq(t *testing.T, got, want string) {
+	t.Helper()
+	if got != want {
+		t.Errorf("etree: unexpected result.\nGot:\n%v\nWanted:\n%v\n", []byte(got), []byte(want))
+	}
+}
+
+func checkIntEq(t *testing.T, got, want int) {
+	t.Helper()
+	if got != want {
+		t.Errorf("etree: unexpected integer. Got: %d. Wanted: %d\n", got, want)
+	}
+}
+
+func checkDocEq(t *testing.T, doc *Document, expected string) {
+	t.Helper()
+	doc.Indent(NoIndent)
+	s, err := doc.WriteToString()
+	if err != nil {
+		t.Error("etree: failed to serialize document")
+	}
+	if s != expected {
+		t.Errorf("etree: unexpected document.\nGot:\n%s\nWanted:\n%s\n", s, expected)
+	}
+}
+
+func checkIndexes(t *testing.T, e *Element) {
+	t.Helper()
+	for i := 0; i < len(e.Child); i++ {
+		c := e.Child[i]
+		if c.Index() != i {
+			t.Errorf("Child index mismatch. Got %d, expected %d.", c.Index(), i)
+		}
+		if ce, ok := c.(*Element); ok {
+			checkIndexes(t, ce)
+		}
+	}
+}
+
 func TestDocument(t *testing.T) {
 	// Create a document
 	doc := NewDocument()
@@ -39,6 +79,8 @@ func TestDocument(t *testing.T) {
 	review.SetCData(">>> Excellent book")
 	doc.IndentTabs()
 
+	checkIndexes(t, &doc.Element)
+
 	// Serialize the document to a string
 	s, err := doc.WriteToString()
 	if err != nil {
@@ -58,7 +100,7 @@ func TestDocument(t *testing.T) {
 	</book>
 </store>
 `
-	checkEq(t, s, expected)
+	checkStrEq(t, s, expected)
 
 	// Test the structure of the XML
 	if doc.Root() != store {
@@ -134,7 +176,7 @@ func TestDocument(t *testing.T) {
 	if element != nil {
 		t.Error("etree: incorrect SelectElement result")
 	}
-	element = book.RemoveChild(title).(*Element)
+	element = book.RemoveChildAt(title.Index()).(*Element)
 	if element != title {
 		t.Error("etree: incorrect RemoveElement result")
 	}
@@ -237,7 +279,7 @@ func TestEscapeCodes(t *testing.T) {
 		if err != nil {
 			t.Error("etree: Escape test produced inocrrect result.")
 		}
-		checkEq(t, s, c.normal)
+		checkStrEq(t, s, c.normal)
 
 		doc.WriteSettings.CanonicalText = false
 		doc.WriteSettings.CanonicalAttrVal = true
@@ -245,7 +287,7 @@ func TestEscapeCodes(t *testing.T) {
 		if err != nil {
 			t.Error("etree: Escape test produced inocrrect result.")
 		}
-		checkEq(t, s, c.attrCanonical)
+		checkStrEq(t, s, c.attrCanonical)
 
 		doc.WriteSettings.CanonicalText = true
 		doc.WriteSettings.CanonicalAttrVal = false
@@ -253,7 +295,7 @@ func TestEscapeCodes(t *testing.T) {
 		if err != nil {
 			t.Error("etree: Escape test produced inocrrect result.")
 		}
-		checkEq(t, s, c.textCanonical)
+		checkStrEq(t, s, c.textCanonical)
 	}
 }
 
@@ -291,7 +333,7 @@ func TestCanonical(t *testing.T) {
   <Person name="Sally" escape="&#xD;&#xA;&#x9;&lt;'&quot;>&amp;"></Person>
 </People>
 `
-	checkEq(t, s, expected)
+	checkStrEq(t, s, expected)
 }
 
 func TestCopy(t *testing.T) {
@@ -334,7 +376,7 @@ func TestCopy(t *testing.T) {
 		t.Error("etree: incorrect FindElement result")
 	}
 
-	e1.parent.RemoveChild(e1)
+	e1.parent.RemoveChildAt(e1.Index())
 	s1, _ = doc.WriteToString()
 	s2, _ = doc2.WriteToString()
 	if s1 == s2 {
@@ -423,7 +465,7 @@ func TestInsertChild(t *testing.T) {
 	year.SetText("1861")
 
 	book := doc.FindElement("//book")
-	book.InsertChild(book.SelectElement("t:title"), year)
+	book.InsertChildAt(book.SelectElement("t:title").Index(), year)
 
 	expected1 := `<book lang="en">
   <year>1861</year>
@@ -433,10 +475,10 @@ func TestInsertChild(t *testing.T) {
 `
 	doc.Indent(2)
 	s1, _ := doc.WriteToString()
-	checkEq(t, s1, expected1)
+	checkStrEq(t, s1, expected1)
 
-	book.RemoveChild(year)
-	book.InsertChild(book.SelectElement("author"), year)
+	book.RemoveChildAt(year.Index())
+	book.InsertChildAt(book.SelectElement("author").Index(), year)
 
 	expected2 := `<book lang="en">
   <t:title>Great Expectations</t:title>
@@ -446,10 +488,10 @@ func TestInsertChild(t *testing.T) {
 `
 	doc.Indent(2)
 	s2, _ := doc.WriteToString()
-	checkEq(t, s2, expected2)
+	checkStrEq(t, s2, expected2)
 
-	book.RemoveChild(year)
-	book.InsertChild(book.SelectElement("UNKNOWN"), year)
+	book.RemoveChildAt(year.Index())
+	book.InsertChildAt(len(book.Child), year)
 
 	expected3 := `<book lang="en">
   <t:title>Great Expectations</t:title>
@@ -459,10 +501,10 @@ func TestInsertChild(t *testing.T) {
 `
 	doc.Indent(2)
 	s3, _ := doc.WriteToString()
-	checkEq(t, s3, expected3)
+	checkStrEq(t, s3, expected3)
 
-	book.RemoveChild(year)
-	book.InsertChild(nil, year)
+	book.RemoveChildAt(year.Index())
+	book.InsertChildAt(999, year)
 
 	expected4 := `<book lang="en">
   <t:title>Great Expectations</t:title>
@@ -472,7 +514,7 @@ func TestInsertChild(t *testing.T) {
 `
 	doc.Indent(2)
 	s4, _ := doc.WriteToString()
-	checkEq(t, s4, expected4)
+	checkStrEq(t, s4, expected4)
 }
 
 func TestCdata(t *testing.T) {
@@ -524,7 +566,7 @@ func TestAddChild(t *testing.T) {
 `
 	doc1.Indent(2)
 	s1, _ := doc1.WriteToString()
-	checkEq(t, s1, expected1)
+	checkStrEq(t, s1, expected1)
 
 	expected2 := `<root>
   <t:title>Great Expectations</t:title>
@@ -533,7 +575,7 @@ func TestAddChild(t *testing.T) {
 `
 	doc2.Indent(2)
 	s2, _ := doc2.WriteToString()
-	checkEq(t, s2, expected2)
+	checkStrEq(t, s2, expected2)
 }
 
 func TestSetRoot(t *testing.T) {
@@ -569,13 +611,13 @@ func TestSetRoot(t *testing.T) {
 `
 	doc.Indent(2)
 	s1, _ := doc.WriteToString()
-	checkEq(t, s1, expected1)
+	checkStrEq(t, s1, expected1)
 
 	doc.SetRoot(origroot)
 	doc.Indent(2)
 	expected2 := testdoc
 	s2, _ := doc.WriteToString()
-	checkEq(t, s2, expected2)
+	checkStrEq(t, s2, expected2)
 
 	doc2 := NewDocument()
 	doc2.CreateProcInst("test", `a="wow"`)
@@ -583,19 +625,19 @@ func TestSetRoot(t *testing.T) {
 	doc2.Indent(2)
 	expected3 := expected1
 	s3, _ := doc2.WriteToString()
-	checkEq(t, s3, expected3)
+	checkStrEq(t, s3, expected3)
 
 	doc2.SetRoot(doc.Root())
 	doc2.Indent(2)
 	expected4 := testdoc
 	s4, _ := doc2.WriteToString()
-	checkEq(t, s4, expected4)
+	checkStrEq(t, s4, expected4)
 
 	expected5 := `<?test a="wow"?>
 `
 	doc.Indent(2)
 	s5, _ := doc.WriteToString()
-	checkEq(t, s5, expected5)
+	checkStrEq(t, s5, expected5)
 }
 
 func TestSortAttrs(t *testing.T) {
@@ -609,7 +651,7 @@ func TestSortAttrs(t *testing.T) {
 	doc.Root().SortAttrs()
 	doc.Indent(2)
 	out, _ := doc.WriteToString()
-	checkEq(t, out, `<el AAA="1" Foo="2" a01="3" aaa="4" foo="5" z="6" สวัสดี="7" a:AAA="8" a:ZZZ="9"/>`+"\n")
+	checkStrEq(t, out, `<el AAA="1" Foo="2" a01="3" aaa="4" foo="5" z="6" สวัสดี="7" a:AAA="8" a:ZZZ="9"/>`+"\n")
 }
 
 func TestCharsetReaderEncoding(t *testing.T) {
@@ -643,7 +685,7 @@ func TestCharData(t *testing.T) {
 		t.Error("etree: failed to serialize document")
 	}
 
-	checkEq(t, s, `<root>This <![CDATA[is ]]>a <![CDATA[text ]]>Element!!</root>`)
+	checkStrEq(t, s, `<root>This <![CDATA[is ]]>a <![CDATA[text ]]>Element!!</root>`)
 
 	// Check we can parse the output
 	err = doc.ReadFromString(s)
@@ -668,7 +710,7 @@ func TestIndentSettings(t *testing.T) {
 		t.Error("etree: failed to serialize document")
 	}
 	expected := "<root><child1><child2/></child1></root>"
-	checkEq(t, s, expected)
+	checkStrEq(t, s, expected)
 
 	// Run all indent test cases.
 	tests := []struct {
@@ -693,7 +735,7 @@ func TestIndentSettings(t *testing.T) {
 			expected := "<root>" + test.nl + tab + "<child1>" + test.nl +
 				tab + tab + "<child2/>" + test.nl + tab +
 				"</child1>" + test.nl + "</root>" + test.nl
-			checkEq(t, s, expected)
+			checkStrEq(t, s, expected)
 		} else {
 			for i := 0; i < 256; i++ {
 				doc.Indent(i)
@@ -705,8 +747,167 @@ func TestIndentSettings(t *testing.T) {
 				expected := "<root>" + test.nl + tab + "<child1>" + test.nl +
 					tab + tab + "<child2/>" + test.nl + tab +
 					"</child1>" + test.nl + "</root>" + test.nl
-				checkEq(t, s, expected)
+				checkStrEq(t, s, expected)
 			}
 		}
 	}
 }
+
+func TestTokenIndexing(t *testing.T) {
+	s := `<?xml version="1.0" encoding="UTF-8"?>
+<?xml-stylesheet type="text/xsl" href="style.xsl"?>
+<store xmlns:t="urn:books-com:titles">
+	<!Directive>
+	<!--This is a comment-->
+	<book lang="en">
+		<t:title>Great Expectations</t:title>
+		<author>Charles Dickens</author>
+		<review/>
+	</book>
+</store>`
+
+	doc := NewDocument()
+	err := doc.ReadFromString(s)
+	if err != nil {
+		t.Error("etree: failed to parse document")
+	}
+
+	review := doc.FindElement("/store/book/review")
+	review.SetText("Excellent")
+
+	checkIndexes(t, &doc.Element)
+
+	doc.Indent(4)
+	checkIndexes(t, &doc.Element)
+
+	doc.Indent(NoIndent)
+	checkIndexes(t, &doc.Element)
+
+	e := NewElement("foo")
+	store := doc.SelectElement("store")
+	store.InsertChildAt(0, e)
+	checkIndexes(t, &doc.Element)
+
+	store.RemoveChildAt(0)
+	checkIndexes(t, &doc.Element)
+}
+
+func TestSetText(t *testing.T) {
+	doc := NewDocument()
+	root := doc.CreateElement("root")
+
+	checkDocEq(t, doc, `<root/>`)
+	checkStrEq(t, root.Text(), "")
+	checkIntEq(t, len(root.Child), 0)
+
+	root.SetText("foo")
+	checkDocEq(t, doc, `<root>foo</root>`)
+	checkStrEq(t, root.Text(), "foo")
+	checkIntEq(t, len(root.Child), 1)
+
+	root.SetText("bar")
+	checkDocEq(t, doc, `<root>bar</root>`)
+	checkStrEq(t, root.Text(), "bar")
+	checkIntEq(t, len(root.Child), 1)
+
+	root.CreateCData("cdata")
+	checkDocEq(t, doc, `<root>bar<![CDATA[cdata]]></root>`)
+	checkStrEq(t, root.Text(), "barcdata")
+	checkIntEq(t, len(root.Child), 2)
+
+	root.SetText("qux")
+	checkDocEq(t, doc, `<root>qux</root>`)
+	checkStrEq(t, root.Text(), "qux")
+	checkIntEq(t, len(root.Child), 1)
+
+	root.CreateCData("cdata")
+	checkDocEq(t, doc, `<root>qux<![CDATA[cdata]]></root>`)
+	checkStrEq(t, root.Text(), "quxcdata")
+	checkIntEq(t, len(root.Child), 2)
+
+	root.SetCData("baz")
+	checkDocEq(t, doc, `<root><![CDATA[baz]]></root>`)
+	checkStrEq(t, root.Text(), "baz")
+	checkIntEq(t, len(root.Child), 1)
+
+	root.CreateText("corge")
+	root.CreateCData("grault")
+	root.CreateText("waldo")
+	root.CreateCData("fred")
+	root.CreateElement("child")
+	checkDocEq(t, doc, `<root><![CDATA[baz]]>corge<![CDATA[grault]]>waldo<![CDATA[fred]]><child/></root>`)
+	checkStrEq(t, root.Text(), "bazcorgegraultwaldofred")
+	checkIntEq(t, len(root.Child), 6)
+
+	root.SetText("plugh")
+	checkDocEq(t, doc, `<root>plugh<child/></root>`)
+	checkStrEq(t, root.Text(), "plugh")
+	checkIntEq(t, len(root.Child), 2)
+
+	root.SetText("")
+	checkDocEq(t, doc, `<root><child/></root>`)
+	checkStrEq(t, root.Text(), "")
+	checkIntEq(t, len(root.Child), 1)
+
+	root.SetText("")
+	checkDocEq(t, doc, `<root><child/></root>`)
+	checkStrEq(t, root.Text(), "")
+	checkIntEq(t, len(root.Child), 1)
+
+	root.RemoveChildAt(0)
+	root.CreateText("corge")
+	root.CreateCData("grault")
+	root.CreateText("waldo")
+	root.CreateCData("fred")
+	root.CreateElement("child")
+	checkDocEq(t, doc, `<root>corge<![CDATA[grault]]>waldo<![CDATA[fred]]><child/></root>`)
+	checkStrEq(t, root.Text(), "corgegraultwaldofred")
+	checkIntEq(t, len(root.Child), 5)
+
+	root.SetText("")
+	checkDocEq(t, doc, `<root><child/></root>`)
+	checkStrEq(t, root.Text(), "")
+	checkIntEq(t, len(root.Child), 1)
+}
+
+func TestSetTail(t *testing.T) {
+	doc := NewDocument()
+	root := doc.CreateElement("root")
+	child := root.CreateElement("child")
+	root.CreateText("\n\t")
+	child.SetText("foo")
+	checkDocEq(t, doc, "<root><child>foo</child>\n\t</root>")
+	checkStrEq(t, child.Tail(), "\n\t")
+	checkIntEq(t, len(root.Child), 2)
+	checkIntEq(t, len(child.Child), 1)
+
+	root.CreateCData("    ")
+	checkDocEq(t, doc, "<root><child>foo</child>\n\t<![CDATA[    ]]></root>")
+	checkStrEq(t, child.Tail(), "\n\t    ")
+	checkIntEq(t, len(root.Child), 3)
+	checkIntEq(t, len(child.Child), 1)
+
+	child.SetTail("")
+	checkDocEq(t, doc, "<root><child>foo</child></root>")
+	checkStrEq(t, child.Tail(), "")
+	checkIntEq(t, len(root.Child), 1)
+	checkIntEq(t, len(child.Child), 1)
+
+	child.SetTail("\t\t\t")
+	checkDocEq(t, doc, "<root><child>foo</child>\t\t\t</root>")
+	checkStrEq(t, child.Tail(), "\t\t\t")
+	checkIntEq(t, len(root.Child), 2)
+	checkIntEq(t, len(child.Child), 1)
+
+	child.SetTail("\t\n\n\t")
+	checkDocEq(t, doc, "<root><child>foo</child>\t\n\n\t</root>")
+	checkStrEq(t, child.Tail(), "\t\n\n\t")
+	checkIntEq(t, len(root.Child), 2)
+	checkIntEq(t, len(child.Child), 1)
+
+	child.SetTail("")
+	checkDocEq(t, doc, "<root><child>foo</child></root>")
+	checkStrEq(t, child.Tail(), "")
+	checkIntEq(t, len(root.Child), 1)
+	checkIntEq(t, len(child.Child), 1)
+}
diff --git a/path_test.go b/path_test.go
index 1b397f3..1e0b972 100644
--- a/path_test.go
+++ b/path_test.go
@@ -180,6 +180,7 @@ func TestPath(t *testing.T) {
 }
 
 func fail(t *testing.T, test test) {
+	t.Helper()
 	t.Errorf("etree: failed test '%s'\n", test.path)
 }