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c7651744da
If you have a struct containing ‘field’, eg:
type t = { field : int }
then previously to pattern-match on this type, eg. in function
parameters, you had to write:
let f { field = field } =
(* ... use field ... *)
In OCaml >= 3.12 it is possible to abbreviate cases where the field
being matched and the variable being bound have the same name, so now
you can just write:
let f { field } =
(* ... use field ... *)
(Similarly for a field prefixed by a Module name you can use
‘{ Module.field }’ instead of ‘{ Module.field = field }’).
This style is widely used inside the OCaml compiler sources, and is
briefer than the long form, so it makes sense to use it. Furthermore
there was one place in virt-dib where we are already using this new
style, so the old code did not compile on OCaml < 3.12.
See also:
https://forge.ocamlcore.org/docman/view.php/77/112/leroy-cug2010.pdf
73 lines
2.3 KiB
OCaml
73 lines
2.3 KiB
OCaml
(* virt-customize
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* Copyright (C) 2016 Red Hat Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*)
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open Std_utils
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open Tools_utils
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open Common_gettext.Gettext
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module G = Guestfs
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let append_line (g : G.guestfs) root path line =
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(* The default line ending for this guest type. This is only
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* used when we don't know anything more about the file.
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*)
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let default_newline () =
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match g#inspect_get_type root with
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| "windows" -> "\r\n"
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| _ -> "\n"
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in
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if not (g#exists path) then (
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g#write path (line ^ default_newline ())
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)
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else (
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(* Stat the file. We want to know it's a regular file, and
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* also its size.
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*)
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let { G.st_mode; st_size = size } = g#statns path in
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if Int64.logand st_mode 0o170000_L <> 0o100000_L then
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error (f_"append_line: %s is not a file") path;
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(* Guess the line ending from the first part of the file, else
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* use the default for this guest type.
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*)
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let newline =
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let content = g#pread path 8192 0L in
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if String.find content "\r\n" >= 0 then "\r\n"
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else if String.find content "\n" >= 0 then "\n"
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else if String.find content "\r" >= 0 then "\r"
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else default_newline () in
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let line = line ^ newline in
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(* Do we need to append a newline to the existing file? *)
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let last_chars =
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let len = String.length newline in
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if size <= 0L then newline (* empty file ends in virtual newline *)
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else if size >= Int64.of_int len then
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g#pread path len (size -^ Int64.of_int len)
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else
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g#pread path len 0L in
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let line =
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if last_chars = newline then line
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else newline ^ line in
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(* Finally, append. *)
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g#write_append path line
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)
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