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go-json/encode_string.go

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package json
import (
"unicode/utf8"
)
// htmlSafeSet holds the value true if the ASCII character with the given
// array position can be safely represented inside a JSON string, embedded
// inside of HTML <script> tags, without any additional escaping.
//
// All values are true except for the ASCII control characters (0-31), the
// double quote ("), the backslash character ("\"), HTML opening and closing
// tags ("<" and ">"), and the ampersand ("&").
var htmlSafeSet = [256]bool{
' ': true,
'!': true,
'"': false,
'#': true,
'$': true,
'%': true,
'&': false,
'\'': true,
'(': true,
')': true,
'*': true,
'+': true,
',': true,
'-': true,
'.': true,
'/': true,
'0': true,
'1': true,
'2': true,
'3': true,
'4': true,
'5': true,
'6': true,
'7': true,
'8': true,
'9': true,
':': true,
';': true,
'<': false,
'=': true,
'>': false,
'?': true,
'@': true,
'A': true,
'B': true,
'C': true,
'D': true,
'E': true,
'F': true,
'G': true,
'H': true,
'I': true,
'J': true,
'K': true,
'L': true,
'M': true,
'N': true,
'O': true,
'P': true,
'Q': true,
'R': true,
'S': true,
'T': true,
'U': true,
'V': true,
'W': true,
'X': true,
'Y': true,
'Z': true,
'[': true,
'\\': false,
']': true,
'^': true,
'_': true,
'`': true,
'a': true,
'b': true,
'c': true,
'd': true,
'e': true,
'f': true,
'g': true,
'h': true,
'i': true,
'j': true,
'k': true,
'l': true,
'm': true,
'n': true,
'o': true,
'p': true,
'q': true,
'r': true,
's': true,
't': true,
'u': true,
'v': true,
'w': true,
'x': true,
'y': true,
'z': true,
'{': true,
'|': true,
'}': true,
'~': true,
'\u007f': true,
0x80: false,
0x81: false,
0x82: false,
0x83: false,
0x84: false,
0x85: false,
0x86: false,
0x87: false,
0x88: false,
0x89: false,
0x8a: false,
0x8b: false,
0x8c: false,
0x8d: false,
0x8e: false,
0x8f: false,
0x90: false,
0x91: false,
0x92: false,
0x93: false,
0x94: false,
0x95: false,
0x96: false,
0x97: false,
0x98: false,
0x99: false,
0x9a: false,
0x9b: false,
0x9c: false,
0x9d: false,
0x9e: false,
0x9f: false,
0xa0: false,
0xa1: false,
0xa2: false,
0xa3: false,
0xa4: false,
0xa5: false,
0xa6: false,
0xa7: false,
0xa8: false,
0xa9: false,
0xaa: false,
0xab: false,
0xac: false,
0xad: false,
0xae: false,
0xaf: false,
0xb0: false,
0xb1: false,
0xb2: false,
0xb3: false,
0xb4: false,
0xb5: false,
0xb6: false,
0xb7: false,
0xb8: false,
0xb9: false,
0xba: false,
0xbb: false,
0xbc: false,
0xbd: false,
0xbe: false,
0xbf: false,
0xc0: false,
0xc1: false,
0xc2: false,
0xc3: false,
0xc4: false,
0xc5: false,
0xc6: false,
0xc7: false,
0xc8: false,
0xc9: false,
0xca: false,
0xcb: false,
0xcc: false,
0xcd: false,
0xce: false,
0xcf: false,
0xd0: false,
0xd1: false,
0xd2: false,
0xd3: false,
0xd4: false,
0xd5: false,
0xd6: false,
0xd7: false,
0xd8: false,
0xd9: false,
0xda: false,
0xdb: false,
0xdc: false,
0xdd: false,
0xde: false,
0xdf: false,
0xe0: false,
0xe1: false,
0xe2: false,
0xe3: false,
0xe4: false,
0xe5: false,
0xe6: false,
0xe7: false,
0xe8: false,
0xe9: false,
0xea: false,
0xeb: false,
0xec: false,
0xed: false,
0xee: false,
0xef: false,
0xf0: false,
0xf1: false,
0xf2: false,
0xf3: false,
0xf4: false,
0xf5: false,
0xf6: false,
0xf7: false,
0xf8: false,
0xf9: false,
0xfa: false,
0xfb: false,
0xfc: false,
0xfd: false,
0xfe: false,
0xff: false,
}
// safeSet holds the value true if the ASCII character with the given array
// position can be represented inside a JSON string without any further
// escaping.
//
// All values are true except for the ASCII control characters (0-31), the
// double quote ("), and the backslash character ("\").
var safeSet = [utf8.RuneSelf]bool{
' ': true,
'!': true,
'"': false,
'#': true,
'$': true,
'%': true,
'&': true,
'\'': true,
'(': true,
')': true,
'*': true,
'+': true,
',': true,
'-': true,
'.': true,
'/': true,
'0': true,
'1': true,
'2': true,
'3': true,
'4': true,
'5': true,
'6': true,
'7': true,
'8': true,
'9': true,
':': true,
';': true,
'<': true,
'=': true,
'>': true,
'?': true,
'@': true,
'A': true,
'B': true,
'C': true,
'D': true,
'E': true,
'F': true,
'G': true,
'H': true,
'I': true,
'J': true,
'K': true,
'L': true,
'M': true,
'N': true,
'O': true,
'P': true,
'Q': true,
'R': true,
'S': true,
'T': true,
'U': true,
'V': true,
'W': true,
'X': true,
'Y': true,
'Z': true,
'[': true,
'\\': false,
']': true,
'^': true,
'_': true,
'`': true,
'a': true,
'b': true,
'c': true,
'd': true,
'e': true,
'f': true,
'g': true,
'h': true,
'i': true,
'j': true,
'k': true,
'l': true,
'm': true,
'n': true,
'o': true,
'p': true,
'q': true,
'r': true,
's': true,
't': true,
'u': true,
'v': true,
'w': true,
'x': true,
'y': true,
'z': true,
'{': true,
'|': true,
'}': true,
'~': true,
'\u007f': true,
}
var hex = "0123456789abcdef"
func (e *Encoder) encodeEscapedString(s string) {
valLen := len(s)
// write string, the fast path, without utf8 and escape support
i := 0
for ; i < valLen; i++ {
if !htmlSafeSet[s[i]] {
break
}
}
e.buf = append(e.buf, '"')
if i == valLen {
e.buf = append(e.buf, s...)
e.buf = append(e.buf, '"')
return
}
e.buf = append(e.buf, s[:i]...)
e.writeStringSlowPathWithHTMLEscaped(i, s, valLen)
}
func (e *Encoder) writeStringSlowPathWithHTMLEscaped(i int, s string, valLen int) {
start := i
// for the remaining parts, we process them char by char
for i < valLen {
if b := s[i]; b < utf8.RuneSelf {
if htmlSafeSet[b] {
i++
continue
}
if start < i {
e.buf = append(e.buf, s[start:i]...)
}
switch b {
case '\\', '"':
e.buf = append(e.buf, '\\', b)
case '\n':
e.buf = append(e.buf, '\\', 'n')
case '\r':
e.buf = append(e.buf, '\\', 'r')
case '\t':
e.buf = append(e.buf, '\\', 't')
default:
// This encodes bytes < 0x20 except for \t, \n and \r.
// If escapeHTML is set, it also escapes <, >, and &
// because they can lead to security holes when
// user-controlled strings are rendered into JSON
// and served to some browsers.
e.buf = append(e.buf, `\u00`...)
e.buf = append(e.buf, hex[b>>4], hex[b&0xF])
}
i++
start = i
continue
}
c, size := utf8.DecodeRuneInString(s[i:])
if c == utf8.RuneError && size == 1 {
if start < i {
e.buf = append(e.buf, s[start:i]...)
}
e.buf = append(e.buf, `\ufffd`...)
i++
start = i
continue
}
// U+2028 is LINE SEPARATOR.
// U+2029 is PARAGRAPH SEPARATOR.
// They are both technically valid characters in JSON strings,
// but don't work in JSONP, which has to be evaluated as JavaScript,
// and can lead to security holes there. It is valid JSON to
// escape them, so we do so unconditionally.
// See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion.
if c == '\u2028' || c == '\u2029' {
if start < i {
e.buf = append(e.buf, s[start:i]...)
}
e.buf = append(e.buf, `\u202`...)
e.buf = append(e.buf, hex[c&0xF])
i += size
start = i
continue
}
i += size
}
if start < len(s) {
e.buf = append(e.buf, s[start:]...)
}
e.buf = append(e.buf, '"')
}
func (e *Encoder) encodeNoEscapedString(s string) {
valLen := len(s)
// write string, the fast path, without utf8 and escape support
i := 0
for ; i < valLen; i++ {
c := s[i]
if c <= 31 || c == '"' || c == '\\' {
break
}
}
e.buf = append(e.buf, '"')
if i == valLen {
e.buf = append(e.buf, s...)
e.buf = append(e.buf, '"')
return
}
e.buf = append(e.buf, s[:i]...)
e.writeStringSlowPath(i, s, valLen)
}
func (e *Encoder) writeStringSlowPath(i int, s string, valLen int) {
start := i
// for the remaining parts, we process them char by char
for i < valLen {
if b := s[i]; b < utf8.RuneSelf {
if safeSet[b] {
i++
continue
}
if start < i {
e.buf = append(e.buf, s[start:i]...)
}
switch b {
case '\\', '"':
e.buf = append(e.buf, '\\', b)
case '\n':
e.buf = append(e.buf, '\\', 'n')
case '\r':
e.buf = append(e.buf, '\\', 'r')
case '\t':
e.buf = append(e.buf, '\\', 't')
default:
// This encodes bytes < 0x20 except for \t, \n and \r.
// If escapeHTML is set, it also escapes <, >, and &
// because they can lead to security holes when
// user-controlled strings are rendered into JSON
// and served to some browsers.
e.buf = append(e.buf, []byte(`\u00`)...)
e.buf = append(e.buf, hex[b>>4], hex[b&0xF])
}
i++
start = i
continue
}
i++
continue
}
if start < len(s) {
e.buf = append(e.buf, s[start:]...)
}
e.buf = append(e.buf, '"')
}
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