1// Copyright 2011 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package html
6
7import (
8 "golang.org/x/net/html/atom"
9)
10
11// A NodeType is the type of a Node.
12type NodeType uint32
13
14const (
15 ErrorNode NodeType = iota
16 TextNode
17 DocumentNode
18 ElementNode
19 CommentNode
20 DoctypeNode
21 // RawNode nodes are not returned by the parser, but can be part of the
22 // Node tree passed to func Render to insert raw HTML (without escaping).
23 // If so, this package makes no guarantee that the rendered HTML is secure
24 // (from e.g. Cross Site Scripting attacks) or well-formed.
25 RawNode
26 scopeMarkerNode
27)
28
29// Section 12.2.4.3 says "The markers are inserted when entering applet,
30// object, marquee, template, td, th, and caption elements, and are used
31// to prevent formatting from "leaking" into applet, object, marquee,
32// template, td, th, and caption elements".
33var scopeMarker = Node{Type: scopeMarkerNode}
34
35// A Node consists of a NodeType and some Data (tag name for element nodes,
36// content for text) and are part of a tree of Nodes. Element nodes may also
37// have a Namespace and contain a slice of Attributes. Data is unescaped, so
38// that it looks like "a<b" rather than "a<b". For element nodes, DataAtom
39// is the atom for Data, or zero if Data is not a known tag name.
40//
41// An empty Namespace implies a "http://www.w3.org/1999/xhtml" namespace.
42// Similarly, "math" is short for "http://www.w3.org/1998/Math/MathML", and
43// "svg" is short for "http://www.w3.org/2000/svg".
44type Node struct {
45 Parent, FirstChild, LastChild, PrevSibling, NextSibling *Node
46
47 Type NodeType
48 DataAtom atom.Atom
49 Data string
50 Namespace string
51 Attr []Attribute
52}
53
54// InsertBefore inserts newChild as a child of n, immediately before oldChild
55// in the sequence of n's children. oldChild may be nil, in which case newChild
56// is appended to the end of n's children.
57//
58// It will panic if newChild already has a parent or siblings.
59func (n *Node) InsertBefore(newChild, oldChild *Node) {
60 if newChild.Parent != nil || newChild.PrevSibling != nil || newChild.NextSibling != nil {
61 panic("html: InsertBefore called for an attached child Node")
62 }
63 var prev, next *Node
64 if oldChild != nil {
65 prev, next = oldChild.PrevSibling, oldChild
66 } else {
67 prev = n.LastChild
68 }
69 if prev != nil {
70 prev.NextSibling = newChild
71 } else {
72 n.FirstChild = newChild
73 }
74 if next != nil {
75 next.PrevSibling = newChild
76 } else {
77 n.LastChild = newChild
78 }
79 newChild.Parent = n
80 newChild.PrevSibling = prev
81 newChild.NextSibling = next
82}
83
84// AppendChild adds a node c as a child of n.
85//
86// It will panic if c already has a parent or siblings.
87func (n *Node) AppendChild(c *Node) {
88 if c.Parent != nil || c.PrevSibling != nil || c.NextSibling != nil {
89 panic("html: AppendChild called for an attached child Node")
90 }
91 last := n.LastChild
92 if last != nil {
93 last.NextSibling = c
94 } else {
95 n.FirstChild = c
96 }
97 n.LastChild = c
98 c.Parent = n
99 c.PrevSibling = last
100}
101
102// RemoveChild removes a node c that is a child of n. Afterwards, c will have
103// no parent and no siblings.
104//
105// It will panic if c's parent is not n.
106func (n *Node) RemoveChild(c *Node) {
107 if c.Parent != n {
108 panic("html: RemoveChild called for a non-child Node")
109 }
110 if n.FirstChild == c {
111 n.FirstChild = c.NextSibling
112 }
113 if c.NextSibling != nil {
114 c.NextSibling.PrevSibling = c.PrevSibling
115 }
116 if n.LastChild == c {
117 n.LastChild = c.PrevSibling
118 }
119 if c.PrevSibling != nil {
120 c.PrevSibling.NextSibling = c.NextSibling
121 }
122 c.Parent = nil
123 c.PrevSibling = nil
124 c.NextSibling = nil
125}
126
127// reparentChildren reparents all of src's child nodes to dst.
128func reparentChildren(dst, src *Node) {
129 for {
130 child := src.FirstChild
131 if child == nil {
132 break
133 }
134 src.RemoveChild(child)
135 dst.AppendChild(child)
136 }
137}
138
139// clone returns a new node with the same type, data and attributes.
140// The clone has no parent, no siblings and no children.
141func (n *Node) clone() *Node {
142 m := &Node{
143 Type: n.Type,
144 DataAtom: n.DataAtom,
145 Data: n.Data,
146 Attr: make([]Attribute, len(n.Attr)),
147 }
148 copy(m.Attr, n.Attr)
149 return m
150}
151
152// nodeStack is a stack of nodes.
153type nodeStack []*Node
154
155// pop pops the stack. It will panic if s is empty.
156func (s *nodeStack) pop() *Node {
157 i := len(*s)
158 n := (*s)[i-1]
159 *s = (*s)[:i-1]
160 return n
161}
162
163// top returns the most recently pushed node, or nil if s is empty.
164func (s *nodeStack) top() *Node {
165 if i := len(*s); i > 0 {
166 return (*s)[i-1]
167 }
168 return nil
169}
170
171// index returns the index of the top-most occurrence of n in the stack, or -1
172// if n is not present.
173func (s *nodeStack) index(n *Node) int {
174 for i := len(*s) - 1; i >= 0; i-- {
175 if (*s)[i] == n {
176 return i
177 }
178 }
179 return -1
180}
181
182// contains returns whether a is within s.
183func (s *nodeStack) contains(a atom.Atom) bool {
184 for _, n := range *s {
185 if n.DataAtom == a && n.Namespace == "" {
186 return true
187 }
188 }
189 return false
190}
191
192// insert inserts a node at the given index.
193func (s *nodeStack) insert(i int, n *Node) {
194 (*s) = append(*s, nil)
195 copy((*s)[i+1:], (*s)[i:])
196 (*s)[i] = n
197}
198
199// remove removes a node from the stack. It is a no-op if n is not present.
200func (s *nodeStack) remove(n *Node) {
201 i := s.index(n)
202 if i == -1 {
203 return
204 }
205 copy((*s)[i:], (*s)[i+1:])
206 j := len(*s) - 1
207 (*s)[j] = nil
208 *s = (*s)[:j]
209}
210
211type insertionModeStack []insertionMode
212
213func (s *insertionModeStack) pop() (im insertionMode) {
214 i := len(*s)
215 im = (*s)[i-1]
216 *s = (*s)[:i-1]
217 return im
218}
219
220func (s *insertionModeStack) top() insertionMode {
221 if i := len(*s); i > 0 {
222 return (*s)[i-1]
223 }
224 return nil
225}