[PATCH 2 of 2] revset: new predicates to find key merge revisions

[Simon Farnsworth]

# HG changeset patch
# User Simon Farnsworth <simonfar at fb.com>
# Date 1456846307 0
#      Tue Mar 01 15:31:47 2016 +0000
# Node ID 9d6c19c8413a039aff8399d6b1db573cb6610fab
# Parent  37fe1f9d08245f7540cb6137c312ae30dbcde688
revset: new predicates to find key merge revisions

When you have tricky merge conflicts, it's useful to look at the history of
the conflict. In a fast moving repository, you're drowned in revisions that
are in the merge but that can't impact on a conflict.

Provide revset predicates to help out; each of conflictbase(pat),
conflictlocal(pat) and conflictother(pat) find conflict base, local and
other revisions for the merge conflicts identified by pat. This, in turn,
enables you to write revsets to find all revisions that are of interest in a
conflict situation.

diff --git a/mercurial/mergestate.py b/mercurial/mergestate.py
--- a/mercurial/mergestate.py
+++ b/mercurial/mergestate.py
@@ -304,6 +304,25 @@
             if entry[0] == 'u':
                 yield f
 
+    def ancestorfilectx(self, dfile):
+        extras = self.extras(dfile)
+        anccommitnode = extras.get('ancestorlinknode')
+        if anccommitnode:
+            actx = self._repo[anccommitnode].rev()
+        else:
+            actx = None
+
+        entry = self._state[dfile]
+        return self._repo.filectx(entry[3], fileid=entry[4], changeid=actx)
+
+    def otherfilectx(self, dfile):
+        entry = self._state[dfile]
+        return self.otherctx.filectx(entry[5], fileid=entry[6])
+
+    def localfilectx(self, dfile):
+        entry = self._state[dfile]
+        return self.localctx.filectx(entry[2])
+
     def driverresolved(self):
         """Obtain the paths of driver-resolved files."""
 
diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -17,6 +17,7 @@
     error,
     hbisect,
     match as matchmod,
+    mergestate as mergestatemod,
     node,
     obsolete as obsmod,
     parser,
@@ -816,6 +817,93 @@
     getargs(x, 0, 0, _("closed takes no arguments"))
     return subset.filter(lambda r: repo[r].closesbranch())
 
+ at predicate('conflictbase(pattern)')
+def conflictbase(repo, subset, x):
+    """The base revision for any merge conflict matching pattern.
+    See :hg:`help patterns` for information about file patterns.
+
+    The pattern without explicit kind like ``glob:`` is expected to be
+    relative to the current directory and match against a file exactly
+    for efficiency.
+    """
+    # i18n: "conflictbase" is a keyword
+    pat = getstring(x, _("conflictbase requires a pattern"))
+    ms = mergestatemod.mergestatereadonly.read(repo)
+
+    if not matchmod.patkind(pat):
+        f = pathutil.canonpath(repo.root, repo.getcwd(), pat)
+        if f in ms:
+            files = [f]
+        else:
+            files = []
+    else:
+        m = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=repo[None])
+        files = (f for f in ms if m(f))
+
+    s = set()
+    for f in files:
+        s.add(ms.ancestorfilectx(f).introrev())
+
+    return subset & s
+
+ at predicate('conflictlocal(pattern)')
+def conflictlocal(repo, subset, x):
+    """The local revision for any merge conflict matching pattern.
+    See :hg:`help patterns` for information about file patterns.
+
+    The pattern without explicit kind like ``glob:`` is expected to be
+    relative to the current directory and match against a file exactly
+    for efficiency.
+    """
+    # i18n: "conflictlocal" is a keyword
+    pat = getstring(x, _("conflictlocal requires a pattern"))
+    ms = mergestatemod.mergestatereadonly.read(repo)
+
+    if not matchmod.patkind(pat):
+        f = pathutil.canonpath(repo.root, repo.getcwd(), pat)
+        if f in ms:
+            files = [f]
+        else:
+            files = []
+    else:
+        m = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=repo[None])
+        files = (f for f in ms if m(f))
+
+    s = set()
+    for f in files:
+        s.add(ms.localfilectx(f).introrev())
+
+    return subset & s
+
+ at predicate('conflictother(pattern)')
+def conflictother(repo, subset, x):
+    """The other revision for any merge conflict matching pattern.
+    See :hg:`help patterns` for information about file patterns.
+
+    The pattern without explicit kind like ``glob:`` is expected to be
+    relative to the current directory and match against a file exactly
+    for efficiency.
+    """
+    # i18n: "conflictother" is a keyword
+    pat = getstring(x, _("conflictother requires a pattern"))
+    ms = mergestatemod.mergestatereadonly.read(repo)
+
+    if not matchmod.patkind(pat):
+        f = pathutil.canonpath(repo.root, repo.getcwd(), pat)
+        if f in ms:
+            files = [f]
+        else:
+            files = []
+    else:
+        m = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=repo[None])
+        files = (f for f in ms if m(f))
+
+    s = set()
+    for f in files:
+        s.add(ms.otherfilectx(f).introrev())
+
+    return subset & s
+
 @predicate('contains(pattern)')
 def contains(repo, subset, x):
     """The revision's manifest contains a file matching pattern (but might not
diff --git a/tests/test-revset.t b/tests/test-revset.t
--- a/tests/test-revset.t
+++ b/tests/test-revset.t
@@ -2230,3 +2230,91 @@
   2
 
   $ cd ..
+
+Test merge conflict predicates
+
+  $ hg init conflictrepo
+  $ cd conflictrepo
+  $ echo file1 > file1
+  $ echo file2 > file2
+  $ hg commit -qAm first
+  $ echo line2 >> file1
+  $ hg commit -qAm second
+  $ hg bookmark base
+  $ hg bookmark tree1
+  $ echo line1 > file1
+  $ hg commit -qAm tree1-file1
+  $ echo tree1-file2 > file2
+  $ hg commit -qAm tree1-file2
+  $ echo file3 > file3
+  $ hg commit -qAm tree1-file3
+  $ hg update base
+  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  (activating bookmark base)
+  $ hg bookmark tree2
+  $ echo lineA > file1
+  $ echo line2 >> file1
+  $ hg commit -qAm tree2
+  $ hg bookmark tree2
+  $ echo tree2-file2 > file2
+  $ hg commit -qAm tree2-file2
+  $ echo file4 > file4
+  $ hg commit -qAm tree2-file4
+
+There are no markers before a merge conflict exists
+
+  $ hg debugrevspec 'conflictbase("glob:*")'
+  $ hg debugrevspec 'conflictlocal("glob:*")'
+  $ hg debugrevspec 'conflictother("glob:*")'
+
+Merge and test that the expected set of markers exist and work with patterns
+
+  $ hg merge --rev tree1 --tool :fail
+  1 files updated, 0 files merged, 0 files removed, 2 files unresolved
+  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
+  [1]
+  $ hg resolve --list
+  U file1
+  U file2
+  $ hg debugrevspec 'conflictbase("glob:*")'
+  0
+  1
+  $ hg debugrevspec 'conflictlocal("glob:*")'
+  5
+  6
+  $ hg debugrevspec 'conflictother("glob:*")'
+  2
+  3
+  $ hg debugrevspec 'conflictbase("file1")'
+  1
+  $ hg debugrevspec 'conflictlocal("file1")'
+  5
+  $ hg debugrevspec 'conflictother("file1")'
+  2
+  $ hg debugrevspec 'conflictbase("file2")'
+  0
+  $ hg debugrevspec 'conflictlocal("file2")'
+  6
+  $ hg debugrevspec 'conflictother("file2")'
+  3
+
+There are no markers on files not in conflict
+  $ hg debugrevspec 'conflictbase("file4")'
+  $ hg debugrevspec 'conflictlocal("file4")'
+  $ hg debugrevspec 'conflictother("file4")'
+
+It's possible to get interesting sets from markers
+
+  $ hg debugrevspec 'conflictbase("glob:*"):conflictlocal("file1")'
+  0
+  1
+  2
+  3
+  4
+  5
+  $ hg debugrevspec 'conflictbase("file2"):conflictother("re:file[1234]")'
+  0
+  1
+  2
+  3
+  $ cd ..