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
|
// Copyright 2010 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 json
import "bytes"
// HTMLEscape appends to dst the JSON-encoded src with <, >, &, U+2028 and U+2029
// characters inside string literals changed to \u003c, \u003e, \u0026, \u2028, \u2029
// so that the JSON will be safe to embed inside HTML <script> tags.
// For historical reasons, web browsers don't honor standard HTML
// escaping within <script> tags, so an alternative JSON encoding must be used.
func HTMLEscape(dst *bytes.Buffer, src []byte) {
dst.Grow(len(src))
dst.Write(appendHTMLEscape(dst.AvailableBuffer(), src))
}
func appendHTMLEscape(dst, src []byte) []byte {
// The characters can only appear in string literals,
// so just scan the string one byte at a time.
start := 0
for i, c := range src {
if c == '<' || c == '>' || c == '&' {
dst = append(dst, src[start:i]...)
dst = append(dst, '\\', 'u', '0', '0', hex[c>>4], hex[c&0xF])
start = i + 1
}
// Convert U+2028 and U+2029 (E2 80 A8 and E2 80 A9).
if c == 0xE2 && i+2 < len(src) && src[i+1] == 0x80 && src[i+2]&^1 == 0xA8 {
dst = append(dst, src[start:i]...)
dst = append(dst, '\\', 'u', '2', '0', '2', hex[src[i+2]&0xF])
start = i + len("\u2029")
}
}
return append(dst, src[start:]...)
}
// Compact appends to dst the JSON-encoded src with
// insignificant space characters elided.
func Compact(dst *bytes.Buffer, src []byte) error {
dst.Grow(len(src))
b := dst.AvailableBuffer()
b, err := appendCompact(b, src, false)
dst.Write(b)
return err
}
func appendCompact(dst, src []byte, escape bool) ([]byte, error) {
origLen := len(dst)
scan := newScanner()
defer freeScanner(scan)
start := 0
for i, c := range src {
if escape && (c == '<' || c == '>' || c == '&') {
dst = append(dst, src[start:i]...)
dst = append(dst, '\\', 'u', '0', '0', hex[c>>4], hex[c&0xF])
start = i + 1
}
// Convert U+2028 and U+2029 (E2 80 A8 and E2 80 A9).
if escape && c == 0xE2 && i+2 < len(src) && src[i+1] == 0x80 && src[i+2]&^1 == 0xA8 {
dst = append(dst, src[start:i]...)
dst = append(dst, '\\', 'u', '2', '0', '2', hex[src[i+2]&0xF])
start = i + len("\u2029")
}
v := scan.step(scan, c)
if v >= scanSkipSpace {
if v == scanError {
break
}
dst = append(dst, src[start:i]...)
start = i + 1
}
}
if scan.eof() == scanError {
return dst[:origLen], scan.err
}
dst = append(dst, src[start:]...)
return dst, nil
}
func appendNewline(dst []byte, prefix, indent string, depth int) []byte {
dst = append(dst, '\n')
dst = append(dst, prefix...)
for i := 0; i < depth; i++ {
dst = append(dst, indent...)
}
return dst
}
// indentGrowthFactor specifies the growth factor of indenting JSON input.
// Empirically, the growth factor was measured to be between 1.4x to 1.8x
// for some set of compacted JSON with the indent being a single tab.
// Specify a growth factor slightly larger than what is observed
// to reduce probability of allocation in appendIndent.
// A factor no higher than 2 ensures that wasted space never exceeds 50%.
const indentGrowthFactor = 2
// Indent appends to dst an indented form of the JSON-encoded src.
// Each element in a JSON object or array begins on a new,
// indented line beginning with prefix followed by one or more
// copies of indent according to the indentation nesting.
// The data appended to dst does not begin with the prefix nor
// any indentation, to make it easier to embed inside other formatted JSON data.
// Although leading space characters (space, tab, carriage return, newline)
// at the beginning of src are dropped, trailing space characters
// at the end of src are preserved and copied to dst.
// For example, if src has no trailing spaces, neither will dst;
// if src ends in a trailing newline, so will dst.
func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
dst.Grow(indentGrowthFactor * len(src))
b := dst.AvailableBuffer()
b, err := appendIndent(b, src, prefix, indent)
dst.Write(b)
return err
}
func appendIndent(dst, src []byte, prefix, indent string) ([]byte, error) {
origLen := len(dst)
scan := newScanner()
defer freeScanner(scan)
needIndent := false
depth := 0
for _, c := range src {
scan.bytes++
v := scan.step(scan, c)
if v == scanSkipSpace {
continue
}
if v == scanError {
break
}
if needIndent && v != scanEndObject && v != scanEndArray {
needIndent = false
depth++
dst = appendNewline(dst, prefix, indent, depth)
}
// Emit semantically uninteresting bytes
// (in particular, punctuation in strings) unmodified.
if v == scanContinue {
dst = append(dst, c)
continue
}
// Add spacing around real punctuation.
switch c {
case '{', '[':
// delay indent so that empty object and array are formatted as {} and [].
needIndent = true
dst = append(dst, c)
case ',':
dst = append(dst, c)
dst = appendNewline(dst, prefix, indent, depth)
case ':':
dst = append(dst, c, ' ')
case '}', ']':
if needIndent {
// suppress indent in empty object/array
needIndent = false
} else {
depth--
dst = appendNewline(dst, prefix, indent, depth)
}
dst = append(dst, c)
default:
dst = append(dst, c)
}
}
if scan.eof() == scanError {
return dst[:origLen], scan.err
}
return dst, nil
}
|
