### view mercurial/mdiff.py @ 120:bae6f0328f63

Add a function to return the new text from a binary diff
author mpm@selenic.com Fri, 20 May 2005 17:42:29 -0800 b942bbe4bb84 8913e13196e1
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```
#!/usr/bin/python
import difflib, struct, mmap

devzero = file("/dev/zero")

def unidiff(a, ad, b, bd, fn):
if not a and not b: return ""
a = a.splitlines(1)
b = b.splitlines(1)
l = list(difflib.unified_diff(a, b, "a/" + fn, "b/" + fn, ad, bd))
return "".join(l)

def textdiff(a, b):
return diff(a.splitlines(1), b.splitlines(1))

def sortdiff(a, b):
la = lb = 0

while 1:
if la >= len(a) or lb >= len(b): break
if b[lb] < a[la]:
si = lb
while lb < len(b) and b[lb] < a[la] : lb += 1
yield "insert", la, la, si, lb
elif a[la] < b[lb]:
si = la
while la < len(a) and a[la] < b[lb]: la += 1
yield "delete", si, la, lb, lb
else:
la += 1
lb += 1

if lb < len(b):
yield "insert", la, la, lb, len(b)

if la < len(a):
yield "delete", la, len(a), lb, lb

def diff(a, b, sorted=0):
bin = []
p = 
for i in a: p.append(p[-1] + len(i))

if sorted:
d = sortdiff(a, b)
else:
d = difflib.SequenceMatcher(None, a, b).get_opcodes()

for o, m, n, s, t in d:
if o == 'equal': continue
s = "".join(b[s:t])
bin.append(struct.pack(">lll", p[m], p[n], len(s)) + s)

return "".join(bin)

def patchtext(bin):
pos = 0
t = []
while pos < len(bin):
p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12])
pos += 12
t.append(bin[pos:pos + l])
pos += l
return "".join(t)

# This attempts to apply a series of patches in time proportional to
# the total size of the patches, rather than patches * len(text). This
# means rather than shuffling strings around, we shuffle around
# pointers to fragments with fragment lists.
#
# When the fragment lists get too long, we collapse them. To do this
# efficiently, we do all our operations inside a buffer created by
# mmap and simply use memmove. This avoids creating a bunch of large
# temporary string buffers.

def patches(a, bins):
if not bins: return a

plens = [len(x) for x in bins]
pl = sum(plens)
bl = len(a) + pl
tl = bl + bl + pl # enough for the patches and two working texts
b1, b2 = 0, bl

if not tl: return a

m = mmap.mmap(devzero.fileno(), tl, mmap.MAP_PRIVATE)

m.write(a)
frags = [(len(a), b1)]

# copy all the patches into our segment so we can memmove from them
pos = b2 + bl
m.seek(pos)
for p in bins: m.write(p)

def pull(dst, src, l): # pull l bytes from src
while l:
f = src.pop(0)
if f > l: # do we need to split?
src.insert(0, (f - l, f + l))
dst.append((l, f))
return
dst.append(f)
l -= f

def collect(buf, list):
start = buf
for l, p in list:
m.move(buf, p, l)
buf += l
return (buf - start, start)

for plen in plens:
# if our list gets too long, execute it
if len(frags) > 128:
b2, b1 = b1, b2
frags = [collect(b1, frags)]

new = []
end = pos + plen
last = 0
while pos < end:
p1, p2, l = struct.unpack(">lll", m[pos:pos + 12])
pull(new, frags, p1 - last) # what didn't change
pull([], frags, p2 - p1)    # what got deleted
new.append((l, pos + 12))        # what got added
pos += l + 12
last = p2
frags = new + frags                    # what was left at the end

t = collect(b2, frags)

return m[t:t + t]

def patch(a, bin):
return patches(a, [bin])

try:
import mpatch
patches = mpatch.patches
except:
pass
```