copies: create helper for getting all copies for changeset

There are a few places where we get all the copies for a changeset (at
least the {file_copies} template and in two places in `hg log
--copies` code). These places currently call scmutil.getrenamedfn() to
get a caching "getrenamed" function. They all use it in a similar
way. We will be able to reuse more code by having a function for
getting all the copies for a changeset. This patch introduces such a
function. It uses it in the {file_copies} template to show that it
works. It relies on the existing scmutil.getrenamedfn() for caching in
the filelog-centric case.

Differential Revision: https://phab.mercurial-scm.org/D6545

mercurial/scmutil.py

@@ -1247,6 +1247,28 b' def getrenamedfn(repo, endrev=None):'
 
     return getrenamed
 
+def getcopiesfn(repo, endrev=None):
+    if copiesmod.usechangesetcentricalgo(repo):
+        def copiesfn(ctx):
+            if ctx.p2copies():
+                allcopies = ctx.p1copies().copy()
+                # There should be no overlap
+                allcopies.update(ctx.p2copies())
+                return sorted(allcopies.items())
+            else:
+                return sorted(ctx.p1copies().items())
+    else:
+        getrenamed = getrenamedfn(repo, endrev)
+        def copiesfn(ctx):
+            copies = []
+            for fn in ctx.files():
+                rename = getrenamed(fn, ctx.rev())
+                if rename:
+                    copies.append((fn, rename))
+            return copies
+
+    return copiesfn
+
 def dirstatecopy(ui, repo, wctx, src, dst, dryrun=False, cwd=None):
     """Update the dirstate to reflect the intent of copying src to dst. For
     different reasons it might not end with dst being marked as copied from src.

mercurial/templatekw.py

@@ -301,14 +301,10 b' def showfilecopies(context, mapping):'
     cache = context.resource(mapping, 'cache')
     copies = context.resource(mapping, 'revcache').get('copies')
     if copies is None:
-        if 'getrenamed' not in cache:
-            cache['getrenamed'] = scmutil.getrenamedfn(repo)
-        copies = []
-        getrenamed = cache['getrenamed']
-        for fn in ctx.files():
-            rename = getrenamed(fn, ctx.rev())
-            if rename:
-                copies.append((fn, rename))
+        if 'getcopies' not in cache:
+            cache['getcopies'] = scmutil.getcopiesfn(repo)
+        getcopies = cache['getcopies']
+        copies = getcopies(ctx)
     return templateutil.compatfilecopiesdict(context, mapping, 'file_copy',
                                              copies)