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jsonx.go
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jsonx.go
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package jsonx
import (
"bytes"
"unicode"
"unicode/utf8"
)
var (
Null = RawMessage("null")
True = RawMessage("true")
False = RawMessage("false")
trueVal = []byte("true") // unnecessary but what if you accidentally override the above?
falseVal = []byte("false") // ^^
nullVal = []byte("null")
)
type Writer interface {
Write(p []byte) (n int, err error)
WriteByte(c byte) error
WriteString(s string) (n int, err error)
}
// IsValid reports whether s is a valid JSON number literal.
//
// Taken from encoding/json
func IsNumber(data []byte) bool {
// This function implements the JSON numbers grammar.
// See https://tools.ietf.org/html/rfc7159#section-6
// and https://www.json.org/img/number.png
if len(data) == 0 {
return false
}
// Optional -
if data[0] == '-' {
data = data[1:]
if len(data) == 0 {
return false
}
}
// Digits
switch {
default:
return false
case data[0] == '0':
data = data[1:]
case '1' <= data[0] && data[0] <= '9':
data = data[1:]
for len(data) > 0 && '0' <= data[0] && data[0] <= '9' {
data = data[1:]
}
}
// . followed by 1 or more digits.
if len(data) >= 2 && data[0] == '.' && '0' <= data[1] && data[1] <= '9' {
data = data[2:]
for len(data) > 0 && '0' <= data[0] && data[0] <= '9' {
data = data[1:]
}
}
// e or E followed by an optional - or + and
// 1 or more digits.
if len(data) >= 2 && (data[0] == 'e' || data[0] == 'E') {
data = data[1:]
if data[0] == '+' || data[0] == '-' {
data = data[1:]
if len(data) == 0 {
return false
}
}
for len(data) > 0 && '0' <= data[0] && data[0] <= '9' {
data = data[1:]
}
}
// Make sure we are at the end.
return len(data) == 0
}
var hex = "0123456789abcdef"
// EncodeString encodes a string to a json string literal, escaping any
// characters that are not permitted.
//
// EncodeString calls EncodeAndWriteString with a bytes.Buffer and returns the
// result.
//
// Logic taken from encoding/json
func EncodeString[S ~string](s S) []byte {
b := bytes.Buffer{}
encodeAndWriteString(&b, []byte(s), true)
return b.Bytes()
}
// EncodeAndWriteString encodes a string to a json string literal, escaping any
// characters that are not permitted. It then writes the result to w.
//
// Logic taken from encoding/json
func EncodeAndWriteString[S ~string](w Writer, s S) {
encodeAndWriteString(w, []byte(s), true)
}
func EncodeAndWriteStringWithoutHTMLEscape(w Writer, s []byte) {
encodeAndWriteString(w, s, false)
}
func encodeAndWriteString(w Writer, s []byte, escapeHTML bool) {
w.WriteByte('"')
start := 0
for i := 0; i < len(s); {
if b := s[i]; b < utf8.RuneSelf {
if htmlSafeSet[b] || (!escapeHTML && safeSet[b]) {
i++
continue
}
if start < i {
w.Write(s[start:i])
}
w.WriteByte('\\')
switch b {
case '\\', '"':
w.WriteByte(b)
case '\n':
w.WriteByte('n')
case '\r':
w.WriteByte('r')
case '\t':
w.WriteByte('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.
w.WriteString(`u00`)
w.WriteByte(hex[b>>4])
w.WriteByte(hex[b&0xF])
}
i++
start = i
continue
}
c, size := utf8.DecodeRune(s[i:])
if c == utf8.RuneError && size == 1 {
if start < i {
w.Write(s[start:i])
}
w.WriteString(`\ufffd`)
i += size
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 {
w.Write(s[start:i])
}
w.WriteString(`\u202`)
w.WriteByte(hex[c&0xF])
i += size
start = i
continue
}
i += size
}
if start < len(s) {
w.Write(s[start:])
}
w.WriteByte('"')
}
func IsNull(d []byte) bool {
return bytes.Equal(d, nullVal)
}
func IsBool(d []byte) bool {
return IsTrue(d) || IsFalse(d)
}
func IsString(d []byte) bool {
return startsAndEndsWith(bytes.TrimSpace(d), '"', '"')
}
func IsObject(d []byte) bool {
return startsAndEndsWith(bytes.TrimSpace(d), '{', '}')
}
func IsArray(d []byte) bool {
return startsAndEndsWith(bytes.TrimSpace(d), '[', ']')
}
func IsEmptyArray(d []byte) bool {
return IsArray(d) && isEmpty(d)
}
// IsTrue reports true if data appears to be a json boolean value of true. It is
// possible that it will report false positives of malformed json as it only
// checks the first character and length.
//
// IsTrue does not parse strings
func IsTrue(d []byte) bool {
return bytes.Equal(d, True)
}
// IsFalse reports true if data appears to be a json boolean value of false. It is
// possible that it will report false positives of malformed json as it only
// checks the first character and length.
//
// IsFalse does not parse strings
func IsFalse(d []byte) bool {
return bytes.Equal(d, falseVal)
}
func isEmpty(d []byte) bool {
count := 0
for _, v := range d {
if !unicode.IsSpace(rune(v)) {
count += 1
if count > 2 {
return false
}
}
}
return count == 2
}
func startsAndEndsWith(d []byte, start, end byte) bool {
if len(d) < 2 {
return false
}
return d[0] == start && d[len(d)-1] == end
}