changeset 51338:2407af4f2eea

delta-find: split the generic part of `_pre_filter_rev` in a method

Since `_pre_filter_rev` contains logic from various sources of constraint, we
start splitting is in subfunction to clarify and document the grouping.

--- a/mercurial/revlogutils/deltas.py	Thu Jan 04 14:39:10 2024 +0100
+++ b/mercurial/revlogutils/deltas.py	Thu Nov 23 18:56:31 2023 +0100
@@ -740,8 +740,13 @@
                 self.tested.add(rev)
         return group
 
-    def _pre_filter_rev(self, rev):
-        """return True if it seems okay to test a rev, False otherwise"""
+    def _pre_filter_rev_universal(self, rev):
+        """pre filtering that is need in all cases.
+
+        return True if it seems okay to test a rev, False otherwise.
+
+        used by _pre_filter_rev.
+        """
         # no need to try a delta against nullrev, this will be done as
         # a last resort.
         if rev == nullrev:
@@ -757,6 +762,15 @@
         # in the revlog
         if self.target_rev is not None and rev >= self.target_rev:
             return False
+        # no delta for rawtext-changing revs (see "candelta" for why)
+        if self.revlog.flags(rev) & REVIDX_RAWTEXT_CHANGING_FLAGS:
+            return False
+        return True
+
+    def _pre_filter_rev(self, rev):
+        """return True if it seems okay to test a rev, False otherwise"""
+        if not self._pre_filter_rev_universal(rev):
+            return False
 
         deltas_limit = self.revinfo.textlen * LIMIT_DELTA2TEXT
         # filter out delta base that will never produce good delta
@@ -774,10 +788,6 @@
         ):
             return False
 
-        # no delta for rawtext-changing revs (see "candelta" for why)
-        if self.revlog.flags(rev) & REVIDX_RAWTEXT_CHANGING_FLAGS:
-            return False
-
         # If we reach here, we are about to build and test a delta.
         # The delta building process will compute the chaininfo in all
         # case, since that computation is cached, it is fine to access