fileset: add revs(revs, fileset) to evaluate set in working directory

Unlike other functions, "revs()" does not select files but switches the
evaluation context. This allow to match file with property in another revision
that the one currently evaluated.

This changeset is based on work from Yuya Nishihara.

mercurial/fileset.py

@@ -15,6 +15,7 b' from . import ('
     merge,
     parser,
     registrar,
+    scmutil,
     util,
 )
 
@@ -438,6 +439,30 b' def copied(mctx, x):'
             s.append(f)
     return s
 
+@predicate('revs(revs, pattern)')
+def revs(mctx, x):
+    """``revs(set, revspec)``
+
+    Evaluate set in the specified revisions. If the revset match multiple revs,
+    this will return file matching pattern in any of the revision.
+    """
+    # i18n: "revs" is a keyword
+    r, x = getargs(x, 2, 2, _("revs takes two arguments"))
+    # i18n: "revs" is a keyword
+    revspec = getstring(r, _("first argument to revs must be a revision"))
+    repo = mctx.ctx.repo()
+    revs = scmutil.revrange(repo, [revspec])
+
+    found = set()
+    result = []
+    for r in revs:
+        ctx = repo[r]
+        for f in getset(mctx.switch(ctx, _buildstatus(ctx, x)), x):
+            if f not in found:
+                found.add(f)
+                result.append(f)
+    return result
+
 @predicate('subrepo([pattern])')
 def subrepo(mctx, x):
     """Subrepositories whose paths match the given pattern.
@@ -512,6 +537,7 b' class fullmatchctx(matchctx):'
 
 # filesets using matchctx.switch()
 _switchcallers = [
+    'revs',
 ]
 
 def _intree(funcs, tree):

mercurial/help/filesets.txt

@@ -69,6 +69,10 b' Some sample queries:'
 
     hg revert "set:copied() and binary() and size('>1M')"
 
+- Revert files that were added to the working directory::
+
+    hg revert "set:wdir(added())"
+
 - Remove files listed in foo.lst that contain the letter a or b::
 
     hg remove "set: 'listfile:foo.lst' and (**a* or **b*)"

tests/test-fileset.t

@@ -88,6 +88,35 b' Test files status'
   $ fileset 'copied()'
   c1
 
+Test files status in different revisions
+
+  $ hg status -m
+  M b2
+  $ fileset -r0 'revs("wdir()", modified())' --traceback
+  b2
+  $ hg status -a
+  A c1
+  $ fileset -r0 'revs("wdir()", added())'
+  c1
+  $ hg status --change 0 -a
+  A a1
+  A a2
+  A b1
+  A b2
+  $ hg status -mru
+  M b2
+  R a2
+  ? c3
+  $ fileset -r0 'added() and revs("wdir()", modified() or removed() or unknown())'
+  b2
+  a2
+  $ fileset -r0 'added() or revs("wdir()", added())'
+  a1
+  a2
+  b1
+  b2
+  c1
+
 Test files properties
 
   >>> file('bin', 'wb').write('\0a')
@@ -367,3 +396,128 b" Test detection of unintentional 'matchct"
 
   $ fileset 'existingcaller()' 2>&1 | tail -1
   AssertionError: unexpected existing() invocation
+
+Test 'revs(...)'
+================
+
+small reminder of the repository state
+
+  $ hg log -G
+  @  changeset:   4:160936123545
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     subrepo
+  |
+  o    changeset:   3:9d594e11b8c9
+  |\   parent:      2:55b05bdebf36
+  | |  parent:      1:830839835f98
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     merge
+  | |
+  | o  changeset:   2:55b05bdebf36
+  | |  parent:      0:8a9576c51c1f
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     diverging
+  | |
+  o |  changeset:   1:830839835f98
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     manychanges
+  |
+  o  changeset:   0:8a9576c51c1f
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     addfiles
+  
+  $ hg status --change 0
+  A a1
+  A a2
+  A b1
+  A b2
+  $ hg status --change 1
+  M b2
+  A 1k
+  A 2k
+  A b2link
+  A bin
+  A c1
+  A con.xml
+  R a2
+  $ hg status --change 2
+  M b2
+  $ hg status --change 3
+  M b2
+  A 1k
+  A 2k
+  A b2link
+  A bin
+  A c1
+  A con.xml
+  R a2
+  $ hg status --change 4
+  A .hgsub
+  A .hgsubstate
+  $ hg status
+  A dos
+  A mac
+  A mixed
+  R con.xml
+  ! a1
+  ? b2.orig
+  ? c3
+  ? unknown
+
+Test files at -r0 should be filtered by files at wdir
+-----------------------------------------------------
+
+  $ fileset -r0 '* and revs("wdir()", *)'
+  a1
+  b1
+  b2
+
+Test that "revs()" work at all
+------------------------------
+
+  $ fileset "revs('2', modified())"
+  b2
+
+Test that "revs()" work for file missing in the working copy/current context
+----------------------------------------------------------------------------
+
+(a2 not in working copy)
+
+  $ fileset "revs('0', added())"
+  a1
+  a2
+  b1
+  b2
+
+(none of the file exist in "0")
+
+  $ fileset -r 0 "revs('4', added())"
+  .hgsub
+  .hgsubstate
+
+Call with empty revset
+--------------------------
+
+  $ fileset "revs('2-2', modified())"
+
+Call with revset matching multiple revs
+---------------------------------------
+
+  $ fileset "revs('0+4', added())"
+  a1
+  a2
+  b1
+  b2
+  .hgsub
+  .hgsubstate
+
+overlapping set
+
+  $ fileset "revs('1+2', modified())"
+  b2