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
|
// 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 (
"bufio"
"fmt"
"io"
"os"
)
type writer interface {
io.Writer
WriteByte(byte) os.Error
WriteString(string) (int, os.Error)
}
// Render renders the parse tree n to the given writer.
//
// For 'well-formed' parse trees, calling Parse on the output of Render will
// result in a clone of the original tree.
//
// 'Well-formed' is not formally specified, but calling Parse on arbitrary
// input results in a 'well-formed' parse tree if Parse does not return an
// error. Programmatically constructed trees are typically also 'well-formed',
// but it is possible to construct a tree that, when rendered and re-parsed,
// results in a different tree. A simple example is that a solitary text node
// would become a tree containing <html>, <head> and <body> elements. Another
// example is that the programmatic equivalent of "a<head>b</head>c" becomes
// "<html><head><head/><body>abc</body></html>".
//
// Comment nodes are elided from the output, analogous to Parse skipping over
// any <!--comment--> input.
func Render(w io.Writer, n *Node) os.Error {
if x, ok := w.(writer); ok {
return render(x, n)
}
buf := bufio.NewWriter(w)
if err := render(buf, n); err != nil {
return err
}
return buf.Flush()
}
func render(w writer, n *Node) os.Error {
// Render non-element nodes; these are the easy cases.
switch n.Type {
case ErrorNode:
return os.NewError("html: cannot render an ErrorNode node")
case TextNode:
return escape(w, n.Data)
case DocumentNode:
for _, c := range n.Child {
if err := render(w, c); err != nil {
return err
}
}
return nil
case ElementNode:
// No-op.
case CommentNode:
return nil
case DoctypeNode:
if _, err := w.WriteString("<!DOCTYPE "); err != nil {
return err
}
if _, err := w.WriteString(n.Data); err != nil {
return err
}
return w.WriteByte('>')
default:
return os.NewError("html: unknown node type")
}
// Render the <xxx> opening tag.
if err := w.WriteByte('<'); err != nil {
return err
}
if _, err := w.WriteString(n.Data); err != nil {
return err
}
for _, a := range n.Attr {
if err := w.WriteByte(' '); err != nil {
return err
}
if _, err := w.WriteString(a.Key); err != nil {
return err
}
if _, err := w.WriteString(`="`); err != nil {
return err
}
if err := escape(w, a.Val); err != nil {
return err
}
if err := w.WriteByte('"'); err != nil {
return err
}
}
if voidElements[n.Data] {
if len(n.Child) != 0 {
return fmt.Errorf("html: void element <%s> has child nodes", n.Data)
}
_, err := w.WriteString("/>")
return err
}
if err := w.WriteByte('>'); err != nil {
return err
}
// Render any child nodes.
switch n.Data {
case "noembed", "noframes", "noscript", "script", "style":
for _, c := range n.Child {
if c.Type != TextNode {
return fmt.Errorf("html: raw text element <%s> has non-text child node", n.Data)
}
if _, err := w.WriteString(c.Data); err != nil {
return err
}
}
case "textarea", "title":
for _, c := range n.Child {
if c.Type != TextNode {
return fmt.Errorf("html: RCDATA element <%s> has non-text child node", n.Data)
}
if err := render(w, c); err != nil {
return err
}
}
default:
for _, c := range n.Child {
if err := render(w, c); err != nil {
return err
}
}
}
// Render the </xxx> closing tag.
if _, err := w.WriteString("</"); err != nil {
return err
}
if _, err := w.WriteString(n.Data); err != nil {
return err
}
return w.WriteByte('>')
}
// Section 13.1.2, "Elements", gives this list of void elements. Void elements
// are those that can't have any contents.
var voidElements = map[string]bool{
"area": true,
"base": true,
"br": true,
"col": true,
"command": true,
"embed": true,
"hr": true,
"img": true,
"input": true,
"keygen": true,
"link": true,
"meta": true,
"param": true,
"source": true,
"track": true,
"wbr": true,
}
|
