func (i *inputBytes) context(pos int) syntax.EmptyOp {
r1, r2 := endOfText, endOfText
if pos > 0 && pos <= len(i.str) {
r1, _ = utf8.DecodeLastRune(i.str[:pos])
}
if pos < len(i.str) {
r2, _ = utf8.DecodeRune(i.str[pos:])
}
return syntax.EmptyOpContext(r1, r2)
}
// lastIndexFunc is the same as LastIndexFunc except that if
// truth==false, the sense of the predicate function is
// inverted.
func lastIndexFunc(s []byte, f func(r int) bool, truth bool) int {
for i := len(s); i > 0; {
rune, size := utf8.DecodeLastRune(s[0:i])
i -= size
if f(rune) == truth {
return i
}
}
return -1
}
// UnreadRune unreads the last rune returned by ReadRune.
// If the most recent read or write operation on the buffer was
// not a ReadRune, UnreadRune returns an error. (In this regard
// it is stricter than UnreadByte, which will unread the last byte
// from any read operation.)
func (b *Buffer) UnreadRune() error {
if b.lastRead != opReadRune {
return errors.New("bytes.Buffer: UnreadRune: previous operation was not ReadRune")
}
b.lastRead = opInvalid
if b.off > 0 {
_, n := utf8.DecodeLastRune(b.buf[0:b.off])
b.off -= n
}
return nil
}
// LastIndexAny interprets s as a sequence of UTF-8-encoded Unicode code
// points. It returns the byte index of the last occurrence in s of any of
// the Unicode code points in chars. It returns -1 if chars is empty or if
// there is no code point in common.
func LastIndexAny(s []byte, chars string) int {
if len(chars) > 0 {
for i := len(s); i > 0; {
rune, size := utf8.DecodeLastRune(s[0:i])
i -= size
for _, m := range chars {
if rune == m {
return i
}
}
}
}
return -1
}
// endsWithCSSKeyword returns whether b ends with an ident that
// case-insensitively matches the lower-case kw.
func endsWithCSSKeyword(b []byte, kw string) bool {
i := len(b) - len(kw)
if i < 0 {
// Too short.
return false
}
if i != 0 {
r, _ := utf8.DecodeLastRune(b[:i])
if isCSSNmchar(r) {
// Too long.
return false
}
}
// Many CSS keywords, such as "!important" can have characters encoded,
// but the URI production does not allow that according to
// http://www.w3.org/TR/css3-syntax/#TOK-URI
// This does not attempt to recognize encoded keywords. For example,
// given "\75\72\6c" and "url" this return false.
return string(bytes.ToLower(b[i:])) == kw
}
// jsValEscaper escapes its inputs to a JS Expression (section 11.14) that has
// nether side-effects nor free variables outside (NaN, Infinity).
func jsValEscaper(args ...interface{}) string {
var a interface{}
if len(args) == 1 {
a = args[0]
switch t := a.(type) {
case JS:
return string(t)
case JSStr:
// TODO: normalize quotes.
return `"` + string(t) + `"`
case json.Marshaler:
// Do not treat as a Stringer.
case fmt.Stringer:
a = t.String()
}
} else {
a = fmt.Sprint(args...)
}
// TODO: detect cycles before calling Marshal which loops infinitely on
// cyclic data. This may be an unnacceptable DoS risk.
b, err := json.Marshal(a)
if err != nil {
// Put a space before comment so that if it is flush against
// a division operator it is not turned into a line comment:
// x/{{y}}
// turning into
// x//* error marshalling y:
// second line of error message */null
return fmt.Sprintf(" /* %s */null ", strings.Replace(err.Error(), "*/", "* /", -1))
}
// TODO: maybe post-process output to prevent it from containing
// "<!--", "-->", "<![CDATA[", "]]>", or "</script"
// in case custom marshallers produce output containing those.
// TODO: Maybe abbreviate \u00ab to \xab to produce more compact output.
if len(b) == 0 {
// In, `x=y/{{.}}*z` a json.Marshaler that produces "" should
// not cause the output `x=y/*z`.
return " null "
}
first, _ := utf8.DecodeRune(b)
last, _ := utf8.DecodeLastRune(b)
var buf bytes.Buffer
// Prevent IdentifierNames and NumericLiterals from running into
// keywords: in, instanceof, typeof, void
pad := isJSIdentPart(first) || isJSIdentPart(last)
if pad {
buf.WriteByte(' ')
}
written := 0
// Make sure that json.Marshal escapes codepoints U+2028 & U+2029
// so it falls within the subset of JSON which is valid JS.
for i := 0; i < len(b); {
rune, n := utf8.DecodeRune(b[i:])
repl := ""
if rune == 0x2028 {
repl = `\u2028`
} else if rune == 0x2029 {
repl = `\u2029`
}
if repl != "" {
buf.Write(b[written:i])
buf.WriteString(repl)
written = i + n
}
i += n
}
if buf.Len() != 0 {
buf.Write(b[written:])
if pad {
buf.WriteByte(' ')
}
b = buf.Bytes()
}
return string(b)
}