diff options
Diffstat (limited to 'lib/pure/unicode.nim')
| -rw-r--r-- | lib/pure/unicode.nim | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/lib/pure/unicode.nim b/lib/pure/unicode.nim index 4a9f4631d..5fd3c2418 100644 --- a/lib/pure/unicode.nim +++ b/lib/pure/unicode.nim @@ -105,6 +105,31 @@ template fastRuneAt*(s: string, i: int, result: expr, doInc = true) = result = Rune(ord(s[i])) when doInc: inc(i) +proc validateUtf8*(s: string): int = + ## returns the position of the invalid byte in ``s`` if the string ``s`` does + ## not hold valid UTF-8 data. Otherwise -1 is returned. + var i = 0 + let L = s.len + while i < L: + if ord(s[i]) <=% 127: + inc(i) + elif ord(s[i]) shr 5 == 0b110: + if i+1 < L and ord(s[i+1]) shr 6 == 0b10: inc(i, 2) + else: return i + elif ord(s[i]) shr 4 == 0b1110: + if i+2 < L and ord(s[i+1]) shr 6 == 0b10 and ord(s[i+2]) shr 6 == 0b10: + inc i, 3 + else: return i + elif ord(s[i]) shr 3 == 0b11110: + if i+3 < L and ord(s[i+1]) shr 6 == 0b10 and + ord(s[i+2]) shr 6 == 0b10 and + ord(s[i+3]) shr 6 == 0b10: + inc i, 4 + else: return i + else: + return i + return -1 + proc runeAt*(s: string, i: Natural): Rune = ## returns the unicode character in `s` at byte index `i` fastRuneAt(s, i, result, false) |