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package goparsify
import (
"bytes"
"unicode/utf8"
)
func StringLit(allowedQuotes string) Parser {
return NewParser("string", func(ps *State) Node {
ps.AutoWS()
for i := 0; i < len(allowedQuotes); i++ {
if ps.Input[ps.Pos] == allowedQuotes[i] {
}
}
if !stringContainsByte(allowedQuotes, ps.Input[ps.Pos]) {
ps.ErrorHere(allowedQuotes)
return Node{}
}
quote := ps.Input[ps.Pos]
var end int = ps.Pos + 1
inputLen := len(ps.Input)
var buf *bytes.Buffer
for end < inputLen {
switch ps.Input[end] {
case '\\':
if end+1 >= inputLen {
ps.ErrorHere(string(quote))
return Node{}
}
if buf == nil {
buf = bytes.NewBufferString(ps.Input[ps.Pos+1 : end])
}
c := ps.Input[end+1]
if c == 'u' {
if end+6 >= inputLen {
ps.Error.Expected = "[a-f0-9]{4}"
ps.Error.pos = end + 2
return Node{}
}
r, ok := unhex(ps.Input[end+2 : end+6])
if !ok {
ps.Error.Expected = "[a-f0-9]"
ps.Error.pos = end + 2
return Node{}
}
buf.WriteRune(r)
end += 6
} else {
buf.WriteByte(c)
end += 2
}
case quote:
if buf == nil {
result := ps.Input[ps.Pos+1 : end]
ps.Pos = end + 1
return Node{Token: result}
}
ps.Pos = end + 1
return Node{Token: buf.String()}
default:
r, w := utf8.DecodeRuneInString(ps.Input[end:])
end += w
if buf != nil {
buf.WriteRune(r)
}
}
}
ps.ErrorHere(string(quote))
return Node{}
})
}
func stringContainsByte(s string, b byte) bool {
for i := 0; i < len(s); i++ {
if b == s[i] {
return true
}
}
return false
}
func unhex(b string) (v rune, ok bool) {
for _, c := range b {
v <<= 4
switch {
case '0' <= c && c <= '9':
v |= c - '0'
case 'a' <= c && c <= 'f':
v |= c - 'a' + 10
case 'A' <= c && c <= 'F':
v |= c - 'A' + 10
default:
return 0, false
}
}
return v, true
}
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