changeset 31655:23391acfc421

py3: fix manifestdict.fastdelta() to be compatible with memoryview

This doesn't look nice, but a straightforward way to support Python 3.
bytes(m[start:end]) is needed because a memoryview doesn't support ordering
operations. On Python 2, m[start:end] returns a bytes object even if m is
a buffer, so calling bytes() should involve no additional copy.

I'm tired of trying cleaner alternatives, including:

 a. extend memoryview to be compatible with buffer type
    => memoryview is not an acceptable base type
 b. wrap memoryview by buffer-like class
    => zlib complains it isn't bytes-like

--- a/mercurial/manifest.py	Sun Mar 26 17:00:23 2017 -0700
+++ b/mercurial/manifest.py	Sun Mar 26 19:06:48 2017 +0900
@@ -650,10 +650,10 @@
     that string.  If start == end the string was not found and
     they indicate the proper sorted insertion point.
 
-    m should be a buffer or a string
-    s is a string'''
+    m should be a buffer, a memoryview or a byte string.
+    s is a byte string'''
     def advance(i, c):
-        while i < lenm and m[i] != c:
+        while i < lenm and m[i:i + 1] != c:
             i += 1
         return i
     if not s:
@@ -664,10 +664,10 @@
     while lo < hi:
         mid = (lo + hi) // 2
         start = mid
-        while start > 0 and m[start - 1] != '\n':
+        while start > 0 and m[start - 1:start] != '\n':
             start -= 1
         end = advance(start, '\0')
-        if m[start:end] < s:
+        if bytes(m[start:end]) < s:
             # we know that after the null there are 40 bytes of sha1
             # this translates to the bisect lo = mid + 1
             lo = advance(end + 40, '\n') + 1