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(* Bindings for Perl-compatible Regular Expressions.
* Copyright (C) 2017 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*)
(* Lightweight bindings for the PCRE library. *)
exception Error of string * int
type regexp
external compile : ?anchored:bool -> ?caseless:bool -> ?dotall:bool -> ?extended:bool -> ?multiline:bool -> string -> regexp = "guestfs_int_pcre_compile_byte" "guestfs_int_pcre_compile"
external matches : ?offset:int -> regexp -> string -> bool = "guestfs_int_pcre_matches"
external sub : int -> string = "guestfs_int_pcre_sub"
external subi : int -> int * int = "guestfs_int_pcre_subi"
let rec replace ?(global = false) patt subst subj =
if not (matches patt subj) then
(* Return original string unchanged if patt doesn't match. *)
subj
else (
(* If patt matches "yyyy" in the original string then we have
* the following situation, where "xxxx" is the part of the
* original string before the match, and "zzzz..." is the
* part after the match:
* "xxxxyyyyzzzzzzzzzzzzz"
* ^ ^
* i1 i2
*)
let i1, i2 = subi 0 in
let xs = String.sub subj 0 i1 (* "xxxx", part before the match *) in
let zs = String.sub subj i2 (String.length subj - i2) (* after *) in
(* If the global flag was set, we want to continue substitutions
* in the rest of the string.
*)
let zs = if global then replace ~global patt subst zs else zs in
xs ^ subst ^ zs
)
let rec split patt subj =
if not (matches patt subj) then
subj, ""
else (
(* If patt matches "yyyy" in the original string then we have
* the following situation, where "xxxx" is the part of the
* original string before the match, and "zzzz..." is the
* part after the match:
* "xxxxyyyyzzzzzzzzzzzzz"
* ^ ^
* i1 i2
*)
let i1, i2 = subi 0 in
let xs = String.sub subj 0 i1 (* "xxxx", part before the match *) in
let zs = String.sub subj i2 (String.length subj - i2) (* after *) in
xs, zs
)
and nsplit ?(max = 0) patt subj =
if max < 0 then
invalid_arg "PCRE.nsplit: max parameter should not be negative";
(* If we reached the limit, OR if the pattern does not match the string
* at all, return the rest of the string as a single element list.
*)
if max = 1 || not (matches patt subj) then
[subj]
else (
let s1, s2 = split patt subj in
let max = if max = 0 then 0 else max - 1 in
s1 :: nsplit ~max patt s2
)
let () =
Callback.register_exception "PCRE.Error" (Error ("", 0))
|
