mercurial/cffi/bdiff.py
author Raphaël Gomès <rgomes@octobus.net>
Tue, 02 Jul 2019 17:15:03 +0200
changeset 42609 326fdce22fb2
parent 33572 857876ebaed4
child 43076 2372284d9457
permissions -rw-r--r--
rust: switch hg-core and hg-cpython to rust 2018 edition Many interesting changes have happened in Rust since the Oxidation Plan was introduced, like the 2018 edition and procedural macros: - Opting in to the 2018 edition is a clear benefit in terms of future proofing, new (nice to have) syntactical sugar notwithstanding. It also has a new non-lexical, non-AST based borrow checker that has fewer bugs(!) and allows us to write correct code that in some cases would have been rejected by the old one. - Procedural macros allow us to use the PyO3 crate which maintainers have expressed the clear goal of compiling on stable, which would help in code maintainability compared to rust-cpython. In this patch are the following changes: - Removing most `extern crate` uses - Updating `use` clauses (`crate` keyword, nested `use`) - Removing `mod.rs` in favor of an aptly named module file Like discussed in the mailing list ( https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-July/132316.html ), until Rust integration in Mercurial is considered to be out of the experimental phase, the maximum version of Rust allowed is whatever the latest version Debian packages. Differential Revision: https://phab.mercurial-scm.org/D6597

# bdiff.py - CFFI implementation of bdiff.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 __future__ import absolute_import

import struct

from ..pure.bdiff import *
from . import _bdiff

ffi = _bdiff.ffi
lib = _bdiff.lib

def blocks(sa, sb):
    a = ffi.new("struct bdiff_line**")
    b = ffi.new("struct bdiff_line**")
    ac = ffi.new("char[]", str(sa))
    bc = ffi.new("char[]", str(sb))
    l = ffi.new("struct bdiff_hunk*")
    try:
        an = lib.bdiff_splitlines(ac, len(sa), a)
        bn = lib.bdiff_splitlines(bc, len(sb), b)
        if not a[0] or not b[0]:
            raise MemoryError
        count = lib.bdiff_diff(a[0], an, b[0], bn, l)
        if count < 0:
            raise MemoryError
        rl = [None] * count
        h = l.next
        i = 0
        while h:
            rl[i] = (h.a1, h.a2, h.b1, h.b2)
            h = h.next
            i += 1
    finally:
        lib.free(a[0])
        lib.free(b[0])
        lib.bdiff_freehunks(l.next)
    return rl

def bdiff(sa, sb):
    a = ffi.new("struct bdiff_line**")
    b = ffi.new("struct bdiff_line**")
    ac = ffi.new("char[]", str(sa))
    bc = ffi.new("char[]", str(sb))
    l = ffi.new("struct bdiff_hunk*")
    try:
        an = lib.bdiff_splitlines(ac, len(sa), a)
        bn = lib.bdiff_splitlines(bc, len(sb), b)
        if not a[0] or not b[0]:
            raise MemoryError
        count = lib.bdiff_diff(a[0], an, b[0], bn, l)
        if count < 0:
            raise MemoryError
        rl = []
        h = l.next
        la = lb = 0
        while h:
            if h.a1 != la or h.b1 != lb:
                lgt = (b[0] + h.b1).l - (b[0] + lb).l
                rl.append(struct.pack(">lll", (a[0] + la).l - a[0].l,
                                      (a[0] + h.a1).l - a[0].l, lgt))
                rl.append(str(ffi.buffer((b[0] + lb).l, lgt)))
            la = h.a2
            lb = h.b2
            h = h.next

    finally:
        lib.free(a[0])
        lib.free(b[0])
        lib.bdiff_freehunks(l.next)
    return "".join(rl)