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module String = StringLabels
type quote =
| Needs_quoting_with_length of int
| No_quoting
let quote_length s =
let n = ref 0 in
let len = String.length s in
let needs_quoting = ref false in
for i = 0 to len - 1 do
n :=
!n
+
match String.unsafe_get s i with
| '\"' | '\\' | '\n' | '\t' | '\r' | '\b' ->
needs_quoting := true;
2
| ' ' ->
needs_quoting := true;
1
| '!' .. '~' -> 1
| _ ->
needs_quoting := true;
4
done;
if !needs_quoting then Needs_quoting_with_length len
else (
assert (len = !n);
No_quoting)
let escape_to s ~dst:s' ~ofs =
let n = ref ofs in
let len = String.length s in
for i = 0 to len - 1 do
(match String.unsafe_get s i with
| ('\"' | '\\') as c ->
Bytes.unsafe_set s' !n '\\';
incr n;
Bytes.unsafe_set s' !n c
| '\n' ->
Bytes.unsafe_set s' !n '\\';
incr n;
Bytes.unsafe_set s' !n 'n'
| '\t' ->
Bytes.unsafe_set s' !n '\\';
incr n;
Bytes.unsafe_set s' !n 't'
| '\r' ->
Bytes.unsafe_set s' !n '\\';
incr n;
Bytes.unsafe_set s' !n 'r'
| '\b' ->
Bytes.unsafe_set s' !n '\\';
incr n;
Bytes.unsafe_set s' !n 'b'
| ' ' .. '~' as c -> Bytes.unsafe_set s' !n c
| c ->
let a = Char.code c in
Bytes.unsafe_set s' !n '\\';
incr n;
Bytes.unsafe_set s' !n (Char.unsafe_chr (48 + (a / 100)));
incr n;
Bytes.unsafe_set s' !n (Char.unsafe_chr (48 + (a / 10 mod 10)));
incr n;
Bytes.unsafe_set s' !n (Char.unsafe_chr (48 + (a mod 10))));
incr n
done
let quote_if_needed s =
let len = String.length s in
match quote_length s with
| No_quoting -> if s = "" then "\"\"" else s
| Needs_quoting_with_length n ->
let s' = Bytes.create (n + 2) in
Bytes.unsafe_set s' 0 '"';
if len = 0 || n > len then escape_to s ~dst:s' ~ofs:1
else Bytes.blit_string ~src:s ~src_pos:0 ~dst:s' ~dst_pos:1 ~len;
Bytes.unsafe_set s' (n + 1) '"';
Bytes.unsafe_to_string s'