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gotosocial/vendor/github.com/goccy/go-json/internal/encoder/string.go
Tobi Smethurst 98263a7de6
Grand test fixup (#138) 
* start fixing up tests

* fix up tests + automate with drone

* fiddle with linting

* messing about with drone.yml

* some more fiddling

* hmmm

* add cache

* add vendor directory

* verbose

* ci updates

* update some little things

* update sig
2021-08-12 21:03:24 +02:00

637 lines
11 KiB
Go
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package encoder
import (
"math/bits"
"reflect"
"unicode/utf8"
"unsafe"
)
const (
lsb = 0x0101010101010101
msb = 0x8080808080808080
)
var needEscapeWithHTML = [256]bool{
'"': true,
'&': true,
'<': true,
'>': true,
'\\': true,
0x00: true,
0x01: true,
0x02: true,
0x03: true,
0x04: true,
0x05: true,
0x06: true,
0x07: true,
0x08: true,
0x09: true,
0x0a: true,
0x0b: true,
0x0c: true,
0x0d: true,
0x0e: true,
0x0f: true,
0x10: true,
0x11: true,
0x12: true,
0x13: true,
0x14: true,
0x15: true,
0x16: true,
0x17: true,
0x18: true,
0x19: true,
0x1a: true,
0x1b: true,
0x1c: true,
0x1d: true,
0x1e: true,
0x1f: true,
/* 0x20 - 0x7f */
0x80: true,
0x81: true,
0x82: true,
0x83: true,
0x84: true,
0x85: true,
0x86: true,
0x87: true,
0x88: true,
0x89: true,
0x8a: true,
0x8b: true,
0x8c: true,
0x8d: true,
0x8e: true,
0x8f: true,
0x90: true,
0x91: true,
0x92: true,
0x93: true,
0x94: true,
0x95: true,
0x96: true,
0x97: true,
0x98: true,
0x99: true,
0x9a: true,
0x9b: true,
0x9c: true,
0x9d: true,
0x9e: true,
0x9f: true,
0xa0: true,
0xa1: true,
0xa2: true,
0xa3: true,
0xa4: true,
0xa5: true,
0xa6: true,
0xa7: true,
0xa8: true,
0xa9: true,
0xaa: true,
0xab: true,
0xac: true,
0xad: true,
0xae: true,
0xaf: true,
0xb0: true,
0xb1: true,
0xb2: true,
0xb3: true,
0xb4: true,
0xb5: true,
0xb6: true,
0xb7: true,
0xb8: true,
0xb9: true,
0xba: true,
0xbb: true,
0xbc: true,
0xbd: true,
0xbe: true,
0xbf: true,
0xc0: true,
0xc1: true,
0xc2: true,
0xc3: true,
0xc4: true,
0xc5: true,
0xc6: true,
0xc7: true,
0xc8: true,
0xc9: true,
0xca: true,
0xcb: true,
0xcc: true,
0xcd: true,
0xce: true,
0xcf: true,
0xd0: true,
0xd1: true,
0xd2: true,
0xd3: true,
0xd4: true,
0xd5: true,
0xd6: true,
0xd7: true,
0xd8: true,
0xd9: true,
0xda: true,
0xdb: true,
0xdc: true,
0xdd: true,
0xde: true,
0xdf: true,
0xe0: true,
0xe1: true,
0xe2: true,
0xe3: true,
0xe4: true,
0xe5: true,
0xe6: true,
0xe7: true,
0xe8: true,
0xe9: true,
0xea: true,
0xeb: true,
0xec: true,
0xed: true,
0xee: true,
0xef: true,
0xf0: true,
0xf1: true,
0xf2: true,
0xf3: true,
0xf4: true,
0xf5: true,
0xf6: true,
0xf7: true,
0xf8: true,
0xf9: true,
0xfa: true,
0xfb: true,
0xfc: true,
0xfd: true,
0xfe: true,
0xff: true,
}
var needEscape = [256]bool{
'"': true,
'\\': true,
0x00: true,
0x01: true,
0x02: true,
0x03: true,
0x04: true,
0x05: true,
0x06: true,
0x07: true,
0x08: true,
0x09: true,
0x0a: true,
0x0b: true,
0x0c: true,
0x0d: true,
0x0e: true,
0x0f: true,
0x10: true,
0x11: true,
0x12: true,
0x13: true,
0x14: true,
0x15: true,
0x16: true,
0x17: true,
0x18: true,
0x19: true,
0x1a: true,
0x1b: true,
0x1c: true,
0x1d: true,
0x1e: true,
0x1f: true,
/* 0x20 - 0x7f */
0x80: true,
0x81: true,
0x82: true,
0x83: true,
0x84: true,
0x85: true,
0x86: true,
0x87: true,
0x88: true,
0x89: true,
0x8a: true,
0x8b: true,
0x8c: true,
0x8d: true,
0x8e: true,
0x8f: true,
0x90: true,
0x91: true,
0x92: true,
0x93: true,
0x94: true,
0x95: true,
0x96: true,
0x97: true,
0x98: true,
0x99: true,
0x9a: true,
0x9b: true,
0x9c: true,
0x9d: true,
0x9e: true,
0x9f: true,
0xa0: true,
0xa1: true,
0xa2: true,
0xa3: true,
0xa4: true,
0xa5: true,
0xa6: true,
0xa7: true,
0xa8: true,
0xa9: true,
0xaa: true,
0xab: true,
0xac: true,
0xad: true,
0xae: true,
0xaf: true,
0xb0: true,
0xb1: true,
0xb2: true,
0xb3: true,
0xb4: true,
0xb5: true,
0xb6: true,
0xb7: true,
0xb8: true,
0xb9: true,
0xba: true,
0xbb: true,
0xbc: true,
0xbd: true,
0xbe: true,
0xbf: true,
0xc0: true,
0xc1: true,
0xc2: true,
0xc3: true,
0xc4: true,
0xc5: true,
0xc6: true,
0xc7: true,
0xc8: true,
0xc9: true,
0xca: true,
0xcb: true,
0xcc: true,
0xcd: true,
0xce: true,
0xcf: true,
0xd0: true,
0xd1: true,
0xd2: true,
0xd3: true,
0xd4: true,
0xd5: true,
0xd6: true,
0xd7: true,
0xd8: true,
0xd9: true,
0xda: true,
0xdb: true,
0xdc: true,
0xdd: true,
0xde: true,
0xdf: true,
0xe0: true,
0xe1: true,
0xe2: true,
0xe3: true,
0xe4: true,
0xe5: true,
0xe6: true,
0xe7: true,
0xe8: true,
0xe9: true,
0xea: true,
0xeb: true,
0xec: true,
0xed: true,
0xee: true,
0xef: true,
0xf0: true,
0xf1: true,
0xf2: true,
0xf3: true,
0xf4: true,
0xf5: true,
0xf6: true,
0xf7: true,
0xf8: true,
0xf9: true,
0xfa: true,
0xfb: true,
0xfc: true,
0xfd: true,
0xfe: true,
0xff: true,
}
var hex = "0123456789abcdef"
// escapeIndex finds the index of the first char in `s` that requires escaping.
// A char requires escaping if it's outside of the range of [0x20, 0x7F] or if
// it includes a double quote or backslash.
// If no chars in `s` require escaping, the return value is -1.
func escapeIndex(s string) int {
chunks := stringToUint64Slice(s)
for _, n := range chunks {
// combine masks before checking for the MSB of each byte. We include
// `n` in the mask to check whether any of the *input* byte MSBs were
// set (i.e. the byte was outside the ASCII range).
mask := n | below(n, 0x20) | contains(n, '"') | contains(n, '\\')
if (mask & msb) != 0 {
return bits.TrailingZeros64(mask&msb) / 8
}
}
valLen := len(s)
for i := len(chunks) * 8; i < valLen; i++ {
if needEscape[s[i]] {
return i
}
}
return -1
}
// below return a mask that can be used to determine if any of the bytes
// in `n` are below `b`. If a byte's MSB is set in the mask then that byte was
// below `b`. The result is only valid if `b`, and each byte in `n`, is below
// 0x80.
func below(n uint64, b byte) uint64 {
return n - expand(b)
}
// contains returns a mask that can be used to determine if any of the
// bytes in `n` are equal to `b`. If a byte's MSB is set in the mask then
// that byte is equal to `b`. The result is only valid if `b`, and each
// byte in `n`, is below 0x80.
func contains(n uint64, b byte) uint64 {
return (n ^ expand(b)) - lsb
}
// expand puts the specified byte into each of the 8 bytes of a uint64.
func expand(b byte) uint64 {
return lsb * uint64(b)
}
//nolint:govet
func stringToUint64Slice(s string) []uint64 {
return *(*[]uint64)(unsafe.Pointer(&reflect.SliceHeader{
Data: ((*reflect.StringHeader)(unsafe.Pointer(&s))).Data,
Len: len(s) / 8,
Cap: len(s) / 8,
}))
}
func AppendEscapedString(buf []byte, s string) []byte {
valLen := len(s)
if valLen == 0 {
return append(buf, `""`...)
}
buf = append(buf, '"')
var (
i, j int
)
if valLen >= 8 {
chunks := stringToUint64Slice(s)
for _, n := range chunks {
// combine masks before checking for the MSB of each byte. We include
// `n` in the mask to check whether any of the *input* byte MSBs were
// set (i.e. the byte was outside the ASCII range).
mask := n | (n - (lsb * 0x20)) |
((n ^ (lsb * '"')) - lsb) |
((n ^ (lsb * '\\')) - lsb) |
((n ^ (lsb * '<')) - lsb) |
((n ^ (lsb * '>')) - lsb) |
((n ^ (lsb * '&')) - lsb)
if (mask & msb) != 0 {
j = bits.TrailingZeros64(mask&msb) / 8
goto ESCAPE_END
}
}
for i := len(chunks) * 8; i < valLen; i++ {
if needEscapeWithHTML[s[i]] {
j = i
goto ESCAPE_END
}
}
// no found any escape characters.
return append(append(buf, s...), '"')
}
ESCAPE_END:
for j < valLen {
c := s[j]
if !needEscapeWithHTML[c] {
// fast path: most of the time, printable ascii characters are used
j++
continue
}
switch c {
case '\\', '"':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', c)
i = j + 1
j = j + 1
continue
case '\n':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', 'n')
i = j + 1
j = j + 1
continue
case '\r':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', 'r')
i = j + 1
j = j + 1
continue
case '\t':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', 't')
i = j + 1
j = j + 1
continue
case '<', '>', '&':
buf = append(buf, s[i:j]...)
buf = append(buf, `\u00`...)
buf = append(buf, hex[c>>4], hex[c&0xF])
i = j + 1
j = j + 1
continue
}
// This encodes bytes < 0x20 except for \t, \n and \r.
if c < 0x20 {
buf = append(buf, s[i:j]...)
buf = append(buf, `\u00`...)
buf = append(buf, hex[c>>4], hex[c&0xF])
i = j + 1
j = j + 1
continue
}
r, size := utf8.DecodeRuneInString(s[j:])
if r == utf8.RuneError && size == 1 {
buf = append(buf, s[i:j]...)
buf = append(buf, `\ufffd`...)
i = j + size
j = j + size
continue
}
switch r {
case '\u2028', '\u2029':
// 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.
buf = append(buf, s[i:j]...)
buf = append(buf, `\u202`...)
buf = append(buf, hex[r&0xF])
i = j + size
j = j + size
continue
}
j += size
}
return append(append(buf, s[i:]...), '"')
}
func AppendString(buf []byte, s string) []byte {
valLen := len(s)
if valLen == 0 {
return append(buf, `""`...)
}
buf = append(buf, '"')
var escapeIdx int
if valLen >= 8 {
if escapeIdx = escapeIndex(s); escapeIdx < 0 {
return append(append(buf, s...), '"')
}
}
i := 0
j := escapeIdx
for j < valLen {
c := s[j]
if c >= 0x20 && c <= 0x7f && c != '\\' && c != '"' {
// fast path: most of the time, printable ascii characters are used
j++
continue
}
switch c {
case '\\', '"':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', c)
i = j + 1
j = j + 1
continue
case '\n':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', 'n')
i = j + 1
j = j + 1
continue
case '\r':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', 'r')
i = j + 1
j = j + 1
continue
case '\t':
buf = append(buf, s[i:j]...)
buf = append(buf, '\\', 't')
i = j + 1
j = j + 1
continue
case '<', '>', '&':
buf = append(buf, s[i:j]...)
buf = append(buf, `\u00`...)
buf = append(buf, hex[c>>4], hex[c&0xF])
i = j + 1
j = j + 1
continue
}
// This encodes bytes < 0x20 except for \t, \n and \r.
if c < 0x20 {
buf = append(buf, s[i:j]...)
buf = append(buf, `\u00`...)
buf = append(buf, hex[c>>4], hex[c&0xF])
i = j + 1
j = j + 1
continue
}
r, size := utf8.DecodeRuneInString(s[j:])
if r == utf8.RuneError && size == 1 {
buf = append(buf, s[i:j]...)
buf = append(buf, `\ufffd`...)
i = j + size
j = j + size
continue
}
switch r {
case '\u2028', '\u2029':
// 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.
buf = append(buf, s[i:j]...)
buf = append(buf, `\u202`...)
buf = append(buf, hex[r&0xF])
i = j + size
j = j + size
continue
}
j += size
}
return append(append(buf, s[i:]...), '"')
}
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