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#!/usr/bin/python
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import difflib, struct, mmap
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devzero = file("/dev/zero")
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def unidiff(a, ad, b, bd, fn):
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if not a and not b: return ""
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a = a.splitlines(1)
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b = b.splitlines(1)
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l = list(difflib.unified_diff(a, b, "a/" + fn, "b/" + fn, ad, bd))
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return "".join(l)
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def textdiff(a, b):
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return diff(a.splitlines(1), b.splitlines(1))
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def sortdiff(a, b):
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la = lb = 0
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while 1:
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if la >= len(a) or lb >= len(b): break
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if b[lb] < a[la]:
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si = lb
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while lb < len(b) and b[lb] < a[la] : lb += 1
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yield "insert", la, la, si, lb
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elif a[la] < b[lb]:
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si = la
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while la < len(a) and a[la] < b[lb]: la += 1
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yield "delete", si, la, lb, lb
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else:
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la += 1
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lb += 1
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if lb < len(b):
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yield "insert", la, la, lb, len(b)
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if la < len(a):
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yield "delete", la, len(a), lb, lb
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def diff(a, b, sorted=0):
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bin = []
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p = [0]
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for i in a: p.append(p[-1] + len(i))
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if sorted:
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d = sortdiff(a, b)
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else:
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d = difflib.SequenceMatcher(None, a, b).get_opcodes()
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for o, m, n, s, t in d:
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if o == 'equal': continue
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s = "".join(b[s:t])
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bin.append(struct.pack(">lll", p[m], p[n], len(s)) + s)
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return "".join(bin)
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# This attempts to apply a series of patches in time proportional to
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# the total size of the patches, rather than patches * len(text). This
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# means rather than shuffling strings around, we shuffle around
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# pointers to fragments with fragment lists.
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#
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# When the fragment lists get too long, we collapse them. To do this
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# efficiently, we do all our operations inside a buffer created by
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# mmap and simply use memmove. This avoids creating a bunch of large
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# temporary string buffers.
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def patches(a, bins):
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if not bins: return a
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plens = [len(x) for x in bins]
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pl = sum(plens)
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bl = len(a) + pl
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tl = bl + bl + pl # enough for the patches and two working texts
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b1, b2 = 0, bl
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if not tl: return a
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m = mmap.mmap(devzero.fileno(), tl, mmap.MAP_PRIVATE)
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# load our original text
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m.write(a)
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frags = [(len(a), b1)]
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# copy all the patches into our segment so we can memmove from them
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pos = b2 + bl
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m.seek(pos)
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for p in bins: m.write(p)
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def pull(dst, src, l): # pull l bytes from src
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while l:
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f = src.pop(0)
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if f[0] > l: # do we need to split?
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src.insert(0, (f[0] - l, f[1] + l))
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dst.append((l, f[1]))
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return
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dst.append(f)
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l -= f[0]
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def collect(buf, list):
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start = buf
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for l, p in list:
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m.move(buf, p, l)
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buf += l
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return (buf - start, start)
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for plen in plens:
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# if our list gets too long, execute it
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if len(frags) > 128:
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b2, b1 = b1, b2
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frags = [collect(b1, frags)]
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new = []
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end = pos + plen
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last = 0
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while pos < end:
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p1, p2, l = struct.unpack(">lll", m[pos:pos + 12])
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pull(new, frags, p1 - last) # what didn't change
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pull([], frags, p2 - p1) # what got deleted
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new.append((l, pos + 12)) # what got added
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pos += l + 12
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last = p2
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frags = new + frags # what was left at the end
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t = collect(b2, frags)
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return m[t[1]:t[1] + t[0]]
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def patch(a, bin):
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return patches(a, [bin])
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try:
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import mpatch
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patches = mpatch.patches
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except:
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pass
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