changeset 37680:e743b8524d60

scmutil: introduce shortesthexnodeidprefix()

We have scmutil.resolvehexnodeidprefix() for resolving a prefix to a
full nodeid, so it makes sense to have the inverse method next to
it. For now it just delegates to changelog.shortest(), but it will
soon also make sure it's called on the unfiltered repo, to match
resolvehexnodeidprefix().

Note that the change in show.py also makes it so the conversion from
revnum to nodeid is done on the filtered repo, but that should be
inconsequential since the revs are all from the filtered repo anyway.

Differential Revision: https://phab.mercurial-scm.org/D3370

--- a/hgext/show.py	Fri Apr 13 11:00:30 2018 -0700
+++ b/hgext/show.py	Fri Apr 13 22:55:01 2018 -0700
@@ -45,6 +45,7 @@
     registrar,
     revset,
     revsetlang,
+    scmutil,
 )
 
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
@@ -447,8 +448,10 @@
     if not revs:
         return minlen
     # don't use filtered repo because it's slow. see templater.shortest().
-    cl = repo.unfiltered().changelog
-    return max(len(cl.shortest(hex(cl.node(r)), minlen)) for r in revs)
+    cl = repo.changelog
+    return max(len(scmutil.shortesthexnodeidprefix(repo.unfiltered(),
+                                                   hex(cl.node(r)),
+                                                   minlen)) for r in revs)
 
 # Adjust the docstring of the show command so it shows all registered views.
 # This is a bit hacky because it runs at the end of module load. When moved

--- a/mercurial/scmutil.py	Fri Apr 13 11:00:30 2018 -0700
+++ b/mercurial/scmutil.py	Fri Apr 13 22:55:01 2018 -0700
@@ -443,6 +443,10 @@
     repo.changelog.rev(node)  # make sure node isn't filtered
     return node
 
+def shortesthexnodeidprefix(repo, hexnode, minlength=1):
+    """Find the shortest unambiguous prefix that matches hexnode."""
+    return repo.changelog.shortest(hexnode, minlength)
+
 def isrevsymbol(repo, symbol):
     """Checks if a symbol exists in the repo.
 

--- a/mercurial/templatefuncs.py	Fri Apr 13 11:00:30 2018 -0700
+++ b/mercurial/templatefuncs.py	Fri Apr 13 22:55:01 2018 -0700
@@ -590,8 +590,8 @@
     # _partialmatch() of filtered changelog could take O(len(repo)) time,
     # which would be unacceptably slow. so we look for hash collision in
     # unfiltered space, which means some hashes may be slightly longer.
-    cl = context.resource(mapping, 'ctx')._repo.unfiltered().changelog
-    return cl.shortest(node, minlength)
+    repo = context.resource(mapping, 'ctx')._repo
+    return scmutil.shortesthexnodeidprefix(repo.unfiltered(), node, minlength)
 
 @templatefunc('strip(text[, chars])')
 def strip(context, mapping, args):