summaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/net/html/node.go
blob: 1350eef22c3ce3846e92656abce8dfa979adbde0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package html

import (
	"golang.org/x/net/html/atom"
)

// A NodeType is the type of a Node.
type NodeType uint32

const (
	ErrorNode NodeType = iota
	TextNode
	DocumentNode
	ElementNode
	CommentNode
	DoctypeNode
	// RawNode nodes are not returned by the parser, but can be part of the
	// Node tree passed to func Render to insert raw HTML (without escaping).
	// If so, this package makes no guarantee that the rendered HTML is secure
	// (from e.g. Cross Site Scripting attacks) or well-formed.
	RawNode
	scopeMarkerNode
)

// Section 12.2.4.3 says "The markers are inserted when entering applet,
// object, marquee, template, td, th, and caption elements, and are used
// to prevent formatting from "leaking" into applet, object, marquee,
// template, td, th, and caption elements".
var scopeMarker = Node{Type: scopeMarkerNode}

// A Node consists of a NodeType and some Data (tag name for element nodes,
// content for text) and are part of a tree of Nodes. Element nodes may also
// have a Namespace and contain a slice of Attributes. Data is unescaped, so
// that it looks like "a<b" rather than "a&lt;b". For element nodes, DataAtom
// is the atom for Data, or zero if Data is not a known tag name.
//
// An empty Namespace implies a "http://www.w3.org/1999/xhtml" namespace.
// Similarly, "math" is short for "http://www.w3.org/1998/Math/MathML", and
// "svg" is short for "http://www.w3.org/2000/svg".
type Node struct {
	Parent, FirstChild, LastChild, PrevSibling, NextSibling *Node

	Type      NodeType
	DataAtom  atom.Atom
	Data      string
	Namespace string
	Attr      []Attribute
}

// InsertBefore inserts newChild as a child of n, immediately before oldChild
// in the sequence of n's children. oldChild may be nil, in which case newChild
// is appended to the end of n's children.
//
// It will panic if newChild already has a parent or siblings.
func (n *Node) InsertBefore(newChild, oldChild *Node) {
	if newChild.Parent != nil || newChild.PrevSibling != nil || newChild.NextSibling != nil {
		panic("html: InsertBefore called for an attached child Node")
	}
	var prev, next *Node
	if oldChild != nil {
		prev, next = oldChild.PrevSibling, oldChild
	} else {
		prev = n.LastChild
	}
	if prev != nil {
		prev.NextSibling = newChild
	} else {
		n.FirstChild = newChild
	}
	if next != nil {
		next.PrevSibling = newChild
	} else {
		n.LastChild = newChild
	}
	newChild.Parent = n
	newChild.PrevSibling = prev
	newChild.NextSibling = next
}

// AppendChild adds a node c as a child of n.
//
// It will panic if c already has a parent or siblings.
func (n *Node) AppendChild(c *Node) {
	if c.Parent != nil || c.PrevSibling != nil || c.NextSibling != nil {
		panic("html: AppendChild called for an attached child Node")
	}
	last := n.LastChild
	if last != nil {
		last.NextSibling = c
	} else {
		n.FirstChild = c
	}
	n.LastChild = c
	c.Parent = n
	c.PrevSibling = last
}

// RemoveChild removes a node c that is a child of n. Afterwards, c will have
// no parent and no siblings.
//
// It will panic if c's parent is not n.
func (n *Node) RemoveChild(c *Node) {
	if c.Parent != n {
		panic("html: RemoveChild called for a non-child Node")
	}
	if n.FirstChild == c {
		n.FirstChild = c.NextSibling
	}
	if c.NextSibling != nil {
		c.NextSibling.PrevSibling = c.PrevSibling
	}
	if n.LastChild == c {
		n.LastChild = c.PrevSibling
	}
	if c.PrevSibling != nil {
		c.PrevSibling.NextSibling = c.NextSibling
	}
	c.Parent = nil
	c.PrevSibling = nil
	c.NextSibling = nil
}

// reparentChildren reparents all of src's child nodes to dst.
func reparentChildren(dst, src *Node) {
	for {
		child := src.FirstChild
		if child == nil {
			break
		}
		src.RemoveChild(child)
		dst.AppendChild(child)
	}
}

// clone returns a new node with the same type, data and attributes.
// The clone has no parent, no siblings and no children.
func (n *Node) clone() *Node {
	m := &Node{
		Type:     n.Type,
		DataAtom: n.DataAtom,
		Data:     n.Data,
		Attr:     make([]Attribute, len(n.Attr)),
	}
	copy(m.Attr, n.Attr)
	return m
}

// nodeStack is a stack of nodes.
type nodeStack []*Node

// pop pops the stack. It will panic if s is empty.
func (s *nodeStack) pop() *Node {
	i := len(*s)
	n := (*s)[i-1]
	*s = (*s)[:i-1]
	return n
}

// top returns the most recently pushed node, or nil if s is empty.
func (s *nodeStack) top() *Node {
	if i := len(*s); i > 0 {
		return (*s)[i-1]
	}
	return nil
}

// index returns the index of the top-most occurrence of n in the stack, or -1
// if n is not present.
func (s *nodeStack) index(n *Node) int {
	for i := len(*s) - 1; i >= 0; i-- {
		if (*s)[i] == n {
			return i
		}
	}
	return -1
}

// contains returns whether a is within s.
func (s *nodeStack) contains(a atom.Atom) bool {
	for _, n := range *s {
		if n.DataAtom == a && n.Namespace == "" {
			return true
		}
	}
	return false
}

// insert inserts a node at the given index.
func (s *nodeStack) insert(i int, n *Node) {
	(*s) = append(*s, nil)
	copy((*s)[i+1:], (*s)[i:])
	(*s)[i] = n
}

// remove removes a node from the stack. It is a no-op if n is not present.
func (s *nodeStack) remove(n *Node) {
	i := s.index(n)
	if i == -1 {
		return
	}
	copy((*s)[i:], (*s)[i+1:])
	j := len(*s) - 1
	(*s)[j] = nil
	*s = (*s)[:j]
}

type insertionModeStack []insertionMode

func (s *insertionModeStack) pop() (im insertionMode) {
	i := len(*s)
	im = (*s)[i-1]
	*s = (*s)[:i-1]
	return im
}

func (s *insertionModeStack) top() insertionMode {
	if i := len(*s); i > 0 {
		return (*s)[i-1]
	}
	return nil
}