[PATCH 3 of 3] revlog: support reading general deltas

[Sune Foldager]

# HG changeset patch
# User Sune Foldager <cryo at cyanite.org>
# Date 1304544568 -7200
# Node ID 7f2e8ed280a6b1c272ec080fd2ca2315a0d264e7
# Parent  39f6e0127ff15c5ad82b989d387402ec83ea30d4
revlog: support reading general deltas

Parentdelta (per entry) takes precedence over generaldelta (per revlog).

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -28,10 +28,11 @@
 REVLOGNG = 1
 REVLOGNGINLINEDATA = (1 << 16)
 REVLOGSHALLOW = (1 << 17)
+REVLOG_GENERALDELTA = (1 << 18)
 REVLOG_DEFAULT_FLAGS = REVLOGNGINLINEDATA
 REVLOG_DEFAULT_FORMAT = REVLOGNG
 REVLOG_DEFAULT_VERSION = REVLOG_DEFAULT_FORMAT | REVLOG_DEFAULT_FLAGS
-REVLOGNG_FLAGS = REVLOGNGINLINEDATA | REVLOGSHALLOW
+REVLOGNG_FLAGS = REVLOGNGINLINEDATA | REVLOGSHALLOW | REVLOG_GENERALDELTA
 
 # revlog index flags
 REVIDX_PARENTDELTA  = 1
@@ -253,6 +254,7 @@
         self.version = v
         self._inline = v & REVLOGNGINLINEDATA
         self._shallow = v & REVLOGSHALLOW
+        self._generaldelta = v & REVLOG_GENERALDELTA
         flags = v & ~0xFFFF
         fmt = v & 0xFFFF
         if fmt == REVLOGV0 and flags:
@@ -841,6 +843,8 @@
     def _deltaparent(self, rev):
         if self.flags(rev) & REVIDX_PARENTDELTA:
             return self.parentrevs(rev)[0]
+        elif self._generaldelta:
+            return self.index[rev][3]
         else:
             return rev - 1