[PATCH 01 of 12] diff: move b85diff to mdiff module

[Guillermo Pérez]

# HG changeset patch
# User Guillermo Pérez <bisho at fb.com>
# Date 1352239445 28800
# Node ID 7234402c9fe3f4520692876ec9fdf6bc1081d2e1
# Parent  fd903f89e42b8e90b6f27e3cb87ca336c200a038
diff: move b85diff to mdiff module

b85diff generates a binary diff, so we move this code to mdiff module
along with unidiff for text diffs. All diffing mechanisms will be in the
same place.

In an upcoming patch we will remove the responsability to print the
index header from the b85diff and move it back to patch, since its
a patch metadata header, not part of the diff generation.

diff --git a/mercurial/mdiff.py b/mercurial/mdiff.py
--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -7,7 +7,8 @@
 
 from i18n import _
 import bdiff, mpatch, util
-import re, struct
+import re, struct, base85, zlib
+from node import hex, nullid
 
 def splitnewlines(text):
     '''like str.splitlines, but only split on newlines.'''
@@ -314,6 +315,44 @@
         for x in yieldhunk(hunk):
             yield x
 
+def b85diff(to, tn):
+    '''print base85-encoded binary diff'''
+    def gitindex(text):
+        if not text:
+            return hex(nullid)
+        l = len(text)
+        s = util.sha1('blob %d\0' % l)
+        s.update(text)
+        return s.hexdigest()
+
+    def fmtline(line):
+        l = len(line)
+        if l <= 26:
+            l = chr(ord('A') + l - 1)
+        else:
+            l = chr(l - 26 + ord('a') - 1)
+        return '%c%s\n' % (l, base85.b85encode(line, True))
+
+    def chunk(text, csize=52):
+        l = len(text)
+        i = 0
+        while i < l:
+            yield text[i:i + csize]
+            i += csize
+
+    tohash = gitindex(to)
+    tnhash = gitindex(tn)
+    if tohash == tnhash:
+        return ""
+
+    # TODO: deltas
+    ret = ['index %s..%s\nGIT binary patch\nliteral %s\n' %
+           (tohash, tnhash, len(tn))]
+    for l in chunk(zlib.compress(tn)):
+        ret.append(fmtline(l))
+    ret.append('\n')
+    return ''.join(ret)
+
 def patchtext(bin):
     pos = 0
     t = []
diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -10,7 +10,7 @@
 import tempfile, zlib, shutil
 
 from i18n import _
-from node import hex, nullid, short
+from node import hex, short
 import base85, mdiff, scmutil, util, diffhelpers, copies, encoding, error
 import context
 
@@ -1514,44 +1514,6 @@
     finally:
         fp.close()
 
-def b85diff(to, tn):
-    '''print base85-encoded binary diff'''
-    def gitindex(text):
-        if not text:
-            return hex(nullid)
-        l = len(text)
-        s = util.sha1('blob %d\0' % l)
-        s.update(text)
-        return s.hexdigest()
-
-    def fmtline(line):
-        l = len(line)
-        if l <= 26:
-            l = chr(ord('A') + l - 1)
-        else:
-            l = chr(l - 26 + ord('a') - 1)
-        return '%c%s\n' % (l, base85.b85encode(line, True))
-
-    def chunk(text, csize=52):
-        l = len(text)
-        i = 0
-        while i < l:
-            yield text[i:i + csize]
-            i += csize
-
-    tohash = gitindex(to)
-    tnhash = gitindex(tn)
-    if tohash == tnhash:
-        return ""
-
-    # TODO: deltas
-    ret = ['index %s..%s\nGIT binary patch\nliteral %s\n' %
-           (tohash, tnhash, len(tn))]
-    for l in chunk(zlib.compress(tn)):
-        ret.append(fmtline(l))
-    ret.append('\n')
-    return ''.join(ret)
-
 class GitDiffRequired(Exception):
     pass
 
@@ -1789,7 +1751,7 @@
 
         if dodiff:
             if dodiff == 'binary':
-                text = b85diff(to, tn)
+                text = mdiff.b85diff(to, tn)
             else:
                 text = mdiff.unidiff(to, date1,
                                     # ctx2 date may be dynamic