1 files changed, 118 insertions, 0 deletions
diff --git a/websdk/mercurial/mpatch.py b/websdk/mercurial/mpatch.py
new file mode 100644
index 0000000..760740d
--- /dev/null
+++ b/websdk/mercurial/mpatch.py
@@ -0,0 +1,118 @@
+# mpatch.py - Python implementation of mpatch.c
+#
+# Copyright 2009 Matt Mackall <mpm@selenic.com> and others
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+import struct
+try:
+    from cStringIO import StringIO
+except ImportError:
+    from StringIO import StringIO
+
+# 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 = StringIO()
+    def move(dest, src, count):
+        """move count bytes from src to dest
+
+        The file pointer is left at the end of dest.
+        """
+        m.seek(src)
+        buf = m.read(count)
+        m.seek(dest)
+        m.write(buf)
+
+    # load our original text
+    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()
+            if f[0] > l: # do we need to split?
+                src.append((f[0] - l, f[1] + l))
+                dst.append((l, f[1]))
+                return
+            dst.append(f)
+            l -= f[0]
+
+    def collect(buf, list):
+        start = buf
+        for l, p in reversed(list):
+            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:
+            m.seek(pos)
+            p1, p2, l = struct.unpack(">lll", m.read(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.extend(reversed(new))                    # what was left at the end
+
+    t = collect(b2, frags)
+
+    m.seek(t[1])
+    return m.read(t[0])
+
+def patchedsize(orig, delta):
+    outlen, last, bin = 0, 0, 0
+    binend = len(delta)
+    data = 12
+
+    while data <= binend:
+        decode = delta[bin:bin + 12]
+        start, end, length = struct.unpack(">lll", decode)
+        if start > end:
+            break
+        bin = data + length
+        data = bin + 12
+        outlen += start - last
+        last = end
+        outlen += length
+
+    if bin != binend:
+        raise ValueError("patch cannot be decoded")
+
+    outlen += orig - last
+    return outlen