templates: add filter to reverse list
The filter supports only lists because for lists, it’s straightforward to
implement. Reversing text doesn’t seem very useful and is hard to implement.
Reversing the bytes would break multi-bytes encodings. Reversing the code
points would break characters consisting of multiple code points. Reversing
graphemes is non-trivial without using a library not included in the standard
library.
# mpatch.py - CFFI implementation of mpatch.c
#
# Copyright 2016 Maciej Fijalkowski <fijall@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from ..pure.mpatch import *
from ..pure.mpatch import mpatchError # silence pyflakes
from . import _mpatch # pytype: disable=import-error
ffi = _mpatch.ffi
lib = _mpatch.lib
@ffi.def_extern()
def cffi_get_next_item(arg, pos):
all, bins = ffi.from_handle(arg)
container = ffi.new(b"struct mpatch_flist*[1]")
to_pass = ffi.new(b"char[]", str(bins[pos]))
all.append(to_pass)
r = lib.mpatch_decode(to_pass, len(to_pass) - 1, container)
if r < 0:
return ffi.NULL
return container[0]
def patches(text, bins):
lgt = len(bins)
all = []
if not lgt:
return text
arg = (all, bins)
patch = lib.mpatch_fold(ffi.new_handle(arg), lib.cffi_get_next_item, 0, lgt)
if not patch:
raise mpatchError(b"cannot decode chunk")
outlen = lib.mpatch_calcsize(len(text), patch)
if outlen < 0:
lib.mpatch_lfree(patch)
raise mpatchError(b"inconsistency detected")
buf = ffi.new(b"char[]", outlen)
if lib.mpatch_apply(buf, text, len(text), patch) < 0:
lib.mpatch_lfree(patch)
raise mpatchError(b"error applying patches")
res = ffi.buffer(buf, outlen)[:]
lib.mpatch_lfree(patch)
return res