Source file regexp.ml
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type regexp =
| Chr of char
| Set of Charset.t
| Seq of regexp list
| Alt of regexp list
| Opt of regexp
| Str of regexp
| Pls of regexp
| Sav of regexp * string ref
let print_regexp ch re =
let rec pregexp ch = function
| Chr(c) -> Printf.fprintf ch "Chr(%C)" c
| Set(s) -> Printf.fprintf ch "Set(%a)" Charset.print s
| Seq(l) -> Printf.fprintf ch "Seq([%a])" pregexps l
| Alt(l) -> Printf.fprintf ch "Alt([%a])" pregexps l
| Opt(r) -> Printf.fprintf ch "Opt(%a)" pregexp r
| Str(r) -> Printf.fprintf ch "Str(%a)" pregexp r
| Pls(r) -> Printf.fprintf ch "Pls(%a)" pregexp r
| Sav(r,_) -> Printf.fprintf ch "Sav(%a,<ref>)" pregexp r
and pregexps ch = function
| [] -> ()
| [r] -> pregexp ch r
| r::rs -> Printf.fprintf ch "%a;%a" pregexp r pregexps rs
in
pregexp ch re
let rec accept_empty = function
| Chr(_) -> false
| Set(_) -> false
| Seq(l) -> List.for_all accept_empty l
| Alt(l) -> List.exists accept_empty l
| Opt(_) -> true
| Str(_) -> true
| Pls(r) -> accept_empty r
| Sav(r,_) -> accept_empty r
let accepted_first_chars : regexp -> Charset.t =
let open Charset in
let rec aux = function
| Chr(c) -> singleton c
| Set(s) -> s
| Seq(l) -> begin
match l with
| [] -> empty
| r::rs -> if accept_empty r then
union (aux r) (aux (Seq(rs)))
else aux r
end
| Alt(l) -> List.fold_left (fun cs r -> union cs (aux r)) empty l
| Opt(r) -> aux r
| Str(r) -> aux r
| Pls(r) -> aux r
| Sav(r,_) -> aux r
in aux
type construction =
Acc of regexp list
| Par of regexp list * regexp list
let push x = function
| Acc l -> Acc (x::l)
| Par (l1, l2) -> Acc(Alt(x :: l1)::l2)
let pop = function
| Acc l -> l
| Par _ -> invalid_arg "Regexp: final bar."
let regexp_from_string : string -> regexp * string ref array = fun s ->
let cs =
let cs = ref [] in
for i = String.length s - 1 downto 0 do
cs := s.[i] :: !cs
done; !cs
in
let read_range cs =
let rec read_range acc = function
| [] -> invalid_arg "Regexp: open charset."
| ']'::cs -> (acc, cs)
| c1::'-'::c2::cs -> let r = Charset.range c1 c2 in
read_range (Charset.union acc r) cs
| c::cs -> read_range (Charset.add acc c) cs
in read_range Charset.empty cs
in
let rec tokens cs =
let is_spe c = List.mem c ['\\';'.';'*';'+';'?';'[';']'] in
match cs with
| '.' ::cs -> `Set(Charset.full) :: tokens cs
| '*' ::cs -> `Str :: tokens cs
| '+' ::cs -> `Pls :: tokens cs
| '?' ::cs -> `Opt :: tokens cs
| '\\'::'('::cs -> `Opn :: tokens cs
| '\\'::')'::cs -> `Cls :: tokens cs
| '\\'::'|'::cs -> `Alt :: tokens cs
| '\\'::c ::cs -> if is_spe c then `Chr(c) :: tokens cs
else invalid_arg "Regexp: invalid escape."
| '\\'::[] -> invalid_arg "Regexp: nothing to escape."
| '[' ::'^':: ']'::cs -> let (rng, cs) = read_range cs in
let rng = Charset.add rng ']' in
`Set(Charset.complement rng) :: tokens cs
| '[' ::']':: cs -> let (rng, cs) = read_range cs in
`Set(Charset.add rng ']') :: tokens cs
| '[' ::'^'::cs -> let (rng, cs) = read_range cs in
`Set(Charset.complement rng) :: tokens cs
| '[' ::cs -> let (rng, cs) = read_range cs in
`Set(rng) :: tokens cs
| c ::cs -> `Chr(c) :: tokens cs
| [] -> []
in
let ts = tokens cs in
let refs = ref [] in
let rec build_re stk acc ts =
match (stk, acc, ts) with
| (stk , acc , `Chr(c)::ts) -> build_re stk (push (Chr c) acc) ts
| (stk , acc , `Set(s)::ts) -> build_re stk (push (Set s) acc) ts
| (stk , Acc(Alt (re::l)::acc), `Str ::ts) -> build_re stk (Acc(Alt(Str re::l) :: acc)) ts
| (stk , Acc(Alt (re::l)::acc), `Pls ::ts) -> build_re stk (Acc(Alt(Pls re::l) :: acc)) ts
| (stk , Acc(Alt (re::l)::acc), `Opt ::ts) -> build_re stk (Acc(Alt(Opt re::l) :: acc)) ts
| (stk , Acc(re::acc), `Str ::ts) -> build_re stk (Acc(Str re :: acc)) ts
| (stk , Acc(re::acc), `Pls ::ts) -> build_re stk (Acc(Pls re :: acc)) ts
| (stk , Acc(re::acc), `Opt ::ts) -> build_re stk (Acc(Opt re :: acc)) ts
| (_ , _ , `Str ::_ )
| (_ , _ , `Pls ::_ )
| (_ , _ , `Opt ::_ ) ->
invalid_arg "Regexp: modifier error."
| (stk , acc , `Opn ::ts) -> build_re (pop acc::stk) (Acc []) ts
| ([] , _ , `Cls ::_ ) ->
invalid_arg "Regexp: group not opened."
| (s::stk, acc , `Cls ::ts) ->
let re =
match List.rev (pop acc) with
| [re] -> re
| l -> Seq(l)
in
let r = ref "" in refs := r :: !refs;
build_re stk (Acc(Sav(re,r)::s)) ts
| (stk , Acc(re::acc), `Alt ::ts) -> build_re stk (Par([re],acc)) ts
| (_ , Acc [] , `Alt ::_ ) ->
invalid_arg "Regexp: initial bar."
| (_ , Par _ , `Alt ::_ ) ->
invalid_arg "Regexp: consecutive bar."
| ([] , acc , [] ) ->
begin
match List.rev (pop acc) with
| [re] -> re
| l -> Seq(l)
end
| (_ , _ , [] ) -> invalid_arg "Regexp: group error."
in
let re = build_re [] (Acc []) ts in
(re, Array.of_list (List.rev !refs))
exception Regexp_error of Input.buffer * int
let regexp_error : type a. Input.buffer -> int -> a = fun buf pos ->
raise (Regexp_error(buf, pos))
let string_of_char_list : char list -> string = fun cs ->
let b = Buffer.create 10 in
List.iter (Buffer.add_char b) cs;
Buffer.contents b
let read_regexp : regexp -> Input.buffer -> int -> Input.buffer * int =
fun re buf pos ->
let rec sread_regexp re buf pos cs =
match re with
| Chr(ch) ->
let (c, buf, pos) = Input.read buf pos in
if c = ch then (c::cs, buf, pos)
else regexp_error buf pos
| Set(chs) ->
let (c, buf, pos) = Input.read buf pos in
if Charset.mem chs c then (c::cs, buf, pos)
else regexp_error buf pos
| Seq(r::rs) ->
let (cs, buf, pos) = sread_regexp r buf pos cs in
sread_regexp (Seq(rs)) buf pos cs
| Seq([]) -> (cs, buf, pos)
| Alt(r::rs) ->
begin
try sread_regexp r buf pos cs
with Regexp_error(_,_) -> sread_regexp (Alt(rs)) buf pos cs
end
| Alt([]) -> regexp_error buf pos
| Opt(r) ->
begin
try sread_regexp r buf pos cs
with Regexp_error(_,_) -> (cs, buf, pos)
end
| Str(r) ->
begin
try
let (cs, buf, pos) = sread_regexp r buf pos cs in
sread_regexp re buf pos cs
with Regexp_error(_,_) -> (cs, buf, pos)
end
| Pls(r) ->
let (cs, buf, pos) = sread_regexp r buf pos cs in
sread_regexp (Str(r)) buf pos cs
| Sav(r,ptr) ->
let cs0 = cs in
let rec fn acc = function
| cs when cs == cs0 -> string_of_char_list acc
| c::cs -> fn (c::acc) cs
| [] -> assert false
in
let (cs, _, _ as res) = sread_regexp r buf pos cs in
ptr := fn [] cs; res
in
let rec read_regexp re buf pos =
match re with
| Chr(ch) ->
let (c, buf, pos) = Input.read buf pos in
if c = ch then (buf, pos)
else regexp_error buf pos
| Set(chs) ->
let (c, buf, pos) = Input.read buf pos in
if Charset.mem chs c then (buf, pos)
else regexp_error buf pos
| Seq(r::rs) ->
let (buf, pos) = read_regexp r buf pos in
read_regexp (Seq(rs)) buf pos
| Seq([]) -> (buf, pos)
| Alt(r::rs) ->
begin
try read_regexp r buf pos
with Regexp_error(_,_) -> read_regexp (Alt(rs)) buf pos
end
| Alt([]) -> regexp_error buf pos
| Opt(r) ->
begin
try read_regexp r buf pos
with Regexp_error(_,_) -> (buf, pos)
end
| Str(r) ->
begin
try
let (buf, pos) = read_regexp r buf pos in
read_regexp re buf pos
with Regexp_error(_,_) -> (buf, pos)
end
| Pls(r) ->
let (buf, pos) = read_regexp r buf pos in
read_regexp (Str(r)) buf pos
| Sav(r,ptr) ->
let (cs, buf, pos) = sread_regexp r buf pos [] in
ptr := string_of_char_list (List.rev cs);
(buf, pos)
in
read_regexp re buf pos